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4iiii Precision Power Meter In-Depth Review


It’s been about 8 months since 4iiii began shipping their Precision power meters to buyers, which is a small pod affixed to your crank arm.  When the company announced their entrance into the market in September 2014, they had planned to debut a self-installable option for both left and right legs.  However, both have been put on hold while they initially rolled out their first version where you send in your crank arms.

The main appeal to the 4iiii product is the low cost – from $399USD for the system, making it the cheapest direct force power meter on the market.

Now, as regular readers know – I first received a unit back in the spring, however, I had complications getting accurate power.  I then received a replacement with the same issues.  Ultimately, it would take nearly 6 months for 4iiii to sort out why my specific pedaling style was causing accuracy issues, which they’ve now solved.  For many (perhaps most?) others, there were no such accuracy issues seen by then.  Nonetheless, during that time period, in lieu of a review, I updated all existing 4iiii posts with warning banners of the problem I was seeing.

All of which brings me to now – about two months after receiving what I’ll simply refer to as a Gen2 unit.  It looks nearly identical, but does contain updated firmware (which all previous units received), as well as some tweaks to the pod and installation process to address the issues I saw.

With that – let’s dive into things.  Oh, and yes, as always the trial unit will go back to 4iiii here shortly.


First up is getting the crank out of the box.  Now keep in mind that the crank arm in my box will differ from the crank arm in your box, because you would have sent in your own crank arm.  So, this is after you’ve sent in your crank for attachment.  The way it works is that you buy the 4iiii Precision unit, and then as part of that you’ll ship your crank arm to them (they pay for shipping both ways).

So once it boomerangs back to you, you’ll be standing around with a nifty packaged up unit:


From there, grab your nearest Ikea knife, and slice away:


Inside you’ll find some paper goodness on top.  This would be a small manual, as well as information about your specific Precision unit.


Additionally, you’ll find two stickers.


Below all that you’ll find the crank arm all packaged up, as well two CR2032 batteries (thus giving you one spare).


Now’s as good as any time to put the battery in.

Finally, here’s a closer look at the crank arm all undressed:





The pod adds 6g of weight without the battery, and 9g of weight with the battery – to your crank arm.  In other words, basically nothing.  With that, let’s get onto installation and configuration.



The installation of Precision is fairly straight forward – especially if you already removed your original crank arm.  If a buddy/shop did the removal of the crank arm, then you’ll likely want to return to them for their services, as you’ll need the same tools.  The exact tools will vary depending on the specific crank arm types and connection points.

In my case, things are relatively straightforward.  Here’s my starting point:


From there, I’m simply going to attach the left crank arm onto the spindle:


And then tighten it down per spec.  If you don’t know the exact torque requirements of your crank arm, I highly encourage you to look it up – as it can and will impact accuracy.  Simply go ask Mr. Google for your crank arm manual, it’s always listed in the first few pages.


Once that’s all done, you’re ready to add pedals of your choice.

In my case, you’ll also see a magnet sensor on there – that’s simply because I use that to help validate cadence results coming from the 4iiii Precision (for testing).  There’s no need/reason to have a separate magnet sensor on the unit.


With that – we’re done and ready to set the zero offset and ride (more on the zero offset in a moment).

(Note: The installation photos I took on the first unit I received, all other photos are from the second generation unit I received.  There’s zero difference between the two in terms of installation.  Just helping to clarify in case you see slight differences with respect to the other power meters on the bike at the time.)

General Use Overview:

When it launched, the Precision power meter was set to be a dual-leg system.  That meant it would have one sensor on each crank arm, similar in concept to Verve’s Infocrank, Garmin’s Vector, Pioneer power meter, and other two-leg capable system.  However, at this time, 4iiii is only shipping a single-leg system.  That single leg being the left crank arm, similar to the Stages power meter, among many others.

Now, I’ll talk about their upcoming dual leg system later in the review, but for now – this is only a single leg system and this review is specifically for the single leg crank arm.

But what does that mean from a technical standpoint?  Well, at its most basic premise they simply double your left leg power.  Of course, most of us have two legs, both of which output power.  So for single left leg systems, they aren’t accounting for your right leg power individually.  Rather, that gets ignored.

This means if your legs have an imbalance (very much normal), your total accuracy might be more variable.  Further, it’s very normal for people to be variably balanced depending on intensity or fatigue.  For example, I tend to be generally balanced up to about 315w (my FTP), but then beyond that, I become rather imbalanced.  In the event that my left leg is weaker, that means my total power is being undercut on a Precision system.  Whereas if left leg was stronger, my total power would be overstated. I’ll talk more about this later in the accuracy section – but I think it’s important to understand from the get-go.

Of course, all of this left-only stuff is most easily seen in that there’s only a single pod on a single crank arm, as seen below:


This pod is effectively non-removable.  While you can remove it from your crank arm, once you’ve done so you’ve ‘destroyed’ the pod.  So think of it as a long-term thing.  For those curious, this would be no different than the Pioneer system, Stages or others.  It’s not designed to transfer from crank arm to crank arm.

The pod runs on a single CR2032 battery, which 4iiii currently says gets about 120 hours of battery life.  That’s up from where it was this spring and summer, where users were getting far less than that.  Firmware updates since then have improved things significantly.  CR2032 batteries are cheap, so even if you’re getting slightly less battery life, you can always buy a pack of 20 them for $7 on Amazon (those are the exact ones I use).


The one area I’m not super thrilled with is the battery cap, which I found can somewhat easily bend it’s slot-system.  It’s not the end of the world, since it’s just the cap part I’m annoyed with, and I haven’t seen any indications it’s causing pod leakage issues (ala Stages Gen1 units).  Still, I’m hoping they’ll improve it down the road.


The 4iiii Precision broadcasts data on both ANT+ and Bluetooth Smart.  While doing this it’ll broadcast your current power & cadence on ANT+, and your current power & cadence on Bluetooth Smart.  Both of which use the standard power meter device profiles on both protocols.

In addition, 4iiii recently released a firmware update which enables Torque Effectiveness & Pedal Smoothness on the Precision system.  However, this firmware update will only be freely available for purchasers of Precision prior to January 15th, 2016.  After that, it sounding like you’d have to pay to get such capabilities.  To be honest, those metrics aren’t probably super-useful in a single-leg configuration.  But to each their own.

If pairing via ANT+, you’ll be able to search and find the 4iiii Precision system via any ANT+ capable power meter head unit.  It’ll then display the ANT+ ID as part of that process.


You can dive in to get additional information such as battery status.  In the case of Precision, setting a crank length value is not required or utilized – so there’s no reason/need to do so.

On the Bluetooth Smart side, I’ve successfully paired it to a Polar M450, and received data from that successfully as well.


You’ll also use Bluetooth Smart to update the firmware on the 4iiii Precision, using the 4iiii app.  This app is also used for other 4iiii products, such as Viiiiva and the original 4iiiii Heads Up Display.  In our case though, we’re just going to use it to update/configure our Precision:


When you search/scan for it and connect to it, it’ll immediately notify you that a firmware update is available.  It’ll then give you details about it:



The firmware update takes less than 60 seconds to complete – so it’s pretty painless.



You can also use the app to complete a zero offset:


Speaking of which, before you head out, you should perform a zero offset on the Precision power meter.  Like many power meter companies, 4iiii recommends doing this before each ride, from their manual:


This can be done from the app, or from your head unit.  If using a head unit, you’ll dive into the calibrate option:


You’ll want to align the crank arms as such, per the manual.  Once it finishes, it’ll provide you two offset numbers, so if you’re recording those, you’ll want to validate you gather both of them.  The first number should be between 8,000 and 11,000, and the second number between 18,000 and 21,000.

In the event your crank arm is out of alignment per the manual, it’ll notify you that calibration has failed, so just check the orientation and try again.  All pretty easy and straightforward.

Once out riding, the unit will display your current power and instant power just like any other power meter.  Like most power meters, it’s usually best to configure one of your data metrics for a ‘smoothed’ power meter value, such as a 3-second (3s) or 10-second (10s) power value, as it helps to reduce some of the variability that is totally normal for power meters.


Note that the 4iiii Precision single-leg system will NOT display power balance, as it’s not measuring your left/right legs independently.  Down the road when they enable a full dual-leg system, that would be a feature of that two-part system.

Finally, I noted earlier that I’m on a Gen2 unit.  That isn’t technically their terminology, though, it’s as close as you’ll get to it.  It means that basically there are some minor hardware tweaks that came about in the September-October timeframe, along with updated firmware.  That firmware is the same as those on Gen1 units.  The main difference was that for me, for my ‘pedaling style’, it apparently caused accuracy issues on Gen1 issues.  What is my ‘pedaling style’?  Well, according to 4iiii, their explanation is as follows (in response to a reader comment a while back):

“As a bit of background, the majority of people pedal in a generally circular motion and receive accurate PRECISION values. For most of us, the crank arm and pedal cause our legs to travel in circles, but a small percentage of cyclists exert unusual forces on the pedals. This is what was happening with Ray. Anyone exhibiting an unusual pedaling style and wanting to compare power data with other meters, will benefit by the firmware upgrade…

…We understand Ray’s quirks – things like Left/Right imbalance, pronation on the pedal (EG: turning your foot in the bracket), leaning on the inside or outside of the pedal and numerous other forces and torques applied. The Precision power meter is unique in that it understands more than just simple bending with an approximate calibration. A real crank arm cannot be accurately approximated by this method for true torque sensing. Further refinement to the build process rectified an issue affecting a limited number of crank models for a small percentage of riding styles. It has been our very unfortunate learning experience that the crank model sent to Ray combined with his style was in that category. Only one person of all the 4iiii’s personnel has been able to present with similar magnitude of error.”

As for how 4iiii reconciles this for existing owners, well…I’m not sure entirely to be honest.  I suspect if you’re experiencing accuracy issues, they’ll take care of you.  But how you’d know you’re having accuracy issues if you don’t have another power meter (or two) for comparison is certainly rather tricky.

Power Meter Accuracy Results:


For my testing period, I used three different 4iiii Precision units (two Gen1 units, and one Gen2 unit), all of which were installed on my triathlon bike, a Cervelo P3C.  Though, all my bikes are configured somewhat similar in terms of testing/validation units, normally with 3-4 power meters in total.


In the case of these tests, the following configuration was used:

A) 4iiii Precision crank-based (left-arm only)
B) PowerTap G3 wheel hub
C) PowerTap P1 pedals
D) PowerTap C1 chainring unit

For indoor tests, I’d usually place it onto a trainer that supported rear wheel usage (generally the CompuTrainer, so I could keep the PowerTap hub on the bike).

From a data collection standpoint, virtually all of the data used in the analysis was collected using Garmin Edge 510/520/810/1000 units, as well as limited M450 usage.  I also recorded some data with NPE WASP units, as well as other applications.  Data analysis is largely done in a custom toolset I use to ferret out differences, while also using more widely available tools like Golden Cheetah, Excel and Training Peaks to validate the results.

Just to set a baseline, the 4iiii Precision has a claimed accuracy range of 0w to 4,000w, at +/- 1%.  Further, it has a claimed cadence range of 10-170RPM.  Remember that the accuracy range is of the left-leg, which can be more variable if you compare it against a left/right system since it’s not capturing the right leg power holistically.

With that, let’s dive into things.  I’m going to pick a few random rides that talk to specific conditions (i.e. temperature changes), sprints, stable power, trainer, etc…  The goal being to find out any oddities that I might see.  You can download all the ride data used in this review at the end of this section (plus a bunch of other random data I tossed in there not shown here in graphs).

(Note: You can also find a few more data points in my PowerTap C1 In-Depth Review, where the 4iiii Precision system was included in various data sets as well.  These two reviews show two different sets of data.)

First up is a ride from last week, where I headed over to a local park and did loops there.  As part of each loop I did a sprint up the hill on the loop.

What you see below is a non-smoothed look at that ride.  Regular readers know that I always show this first, just to show how useless it is in analyzing data.  This chart actually shows four different power meters plotted on the same graph.


Instead, I prefer looking at smoothed data, which helps us to easily spot where things get misaligned.  In this case, I’ve applied a 30-second smoothing to the exact same chart as above, giving us the below.

In the right hand corner is the key to the different colors.  The wattages you see next to it are merely the single points in time where my mouse is, it’s not showing averages.


So why not show averages?  Well, they can be sorta-interesting, but also super-deceiving.  A power meter can be ‘wrong’ 100% of the time, yet still actually be correct for an average.  It’s the easiest bar to pass.  I’ve demonstrated numerous times that simple $99 power solutions like the PowerCal can be very close using averages.

Nonetheless, for those curious, here’s the various averages and maximums from that ride:


The problem with looking at stats like 1-second power, is that it gets to the nuances of how power meters and head units talk to each other.

For fun, I’ve picked a section of the previously noted chart and zoomed in on it.  I’ve also reduced the smoothing to 10s (giving more variability).  In this case, it’s my first sprint of the night.  You can see that all four power meters track very closely both pre-sprint at steady-state (approx. 300w), and then into the sprint (approx. 700w).  Generally speaking pre/post sprint they were within 10w of each other.  And then during the sprint, that grew slightly to a max spread of 31w.


But there’s a catch – which is that the above chart makes some incorrect assumptions.  Specifically, it’s not actually comparing ‘like to like’.  In the case of Precision, it’s technically incorrect to compare it to a PowerTap G3 or the P1, or the C1 units.  Why?  Because those are all measuring my left/right leg totals.  Whereas the Precision (like Stages) is just measuring my left side.  So in the above case, the Precision measured ‘high’ at my sprint peak.

What if instead we just compared the left-only reading from the PowerTap P1 pedal, to that of the left-only reading of the Precision?  Ask and you shall receive:


So what do you see above?  Well, just the left-leg power.  We see that the P1 is slightly higher than the Precision, which is logical (it’s closer to your leg).  We see the two agree on max power – being within 2w of each other (0.6% difference).  Whereas at lower wattages, it’s in the 5-8w range.

I picked another sprint later on, here’s the difference there.


It’s actually interesting – I think this is the first time anyone has ever shown comparing one-leg portions in a power meter review.  Given the bike at the time only has two left-only capable units, it’s impossible to know which one is truly correct.  Once I add the WatTeam left/right capable system to the bike here shortly, I may be able to narrow it down.  But we’re really at the point of splitting hairs.

Moving onto another ride…

Here’s the 30s smoothed version of this one.  Quite frankly, things look really darn pretty at the 30,000ft level:


So let’s dive into some of the peak power, and reduce the smoothing to 5s:


Woah – so in this case Precision for this sprint is showing 50w higher than the others.  So let’s investigate. What does the left-only data say about that?


It shows a difference of about 12w, and then grows slightly to 21w.  Again, there’s no way to know which one of these is correct.  It could be the P1 or the Precision (or somewhere half-way in between).

Now this is where we can start to see some of the impact of left-only, when I apply a Mean-Max graph, which plots max wattages over various timeframes.  You’ll see that up through about 600w @ 30s, things align beautifully, but after that it appears that my left leg was slightly stronger during the sprint – causing some higher values once doubled.  To be clear, this isn’t a negative mark on the technical accuracy of Precision, but just the reality of doubling left-leg power.


Finally, a quick look at cadence on that ride.  You’ll see things largely matched quite well.  There’s one blip on the PowerTap G3 around 1/3rd the way through – but that’s estimated cadence, and there’s nuances that can cause those blips.  Also, don’t overthink slight differences in cadence when you stop/start pedaling.  That’s really an artifact of the way each power meter and associated head unit handles that split-second where the pedals stop moving.


The above ride is interesting, as it included numerous cobbles sections, as circled on the map below.  Cobbles can cause cadence ‘issues’ or variances – which we don’t see above.


Finally, one last quick one before we wrap-up.  This one on an indoor trainer (note: I’ve snipped off the end of the workout where there was some interference in some data sets).


I’ve included this one for fun, merely to point out what happens when I do left/right leg drills.  You can see there that when I’m pedaling with only my right leg, the 4iiii Precision will drop-out entirely (as expected, since no load is going through the left crank arm).  Meanwhile, when I pedal with just my left leg – it doubles it and shows twice as much power (an artifact of the business as usual doubling of the left leg).

Beyond that, the units all track fairly well – including through the 30/30’s, though Precision is a touch bit lower.  In taking a look at the left-only track of the P1, sure enough it’s also lower, indicating that for whatever reason that night my left leg was less powerful.  Interestingly – this somewhat matches what I observed back when I looked at this when Stages first came out.  In that I’ve seen slight variations between indoor and outdoor rides in terms of balance between my legs.

In any case, I’m not seeing anything that’s of concern when it comes to the accuracy of the 4iiii Precision units at this point, with current firmware/hardware – everything tracks very well and without issue.

(Here’s a link to all my 4iiii Precision review data, including all comparative sets.)

(Note: All of the charts in these accuracy sections were created using the DCR Analyzer tool.  It allows you to compare power meters/trainers, heart rate, cadence, speed/pace, GPS tracks and plenty more. You can use it as well, more details here.)

A Brief Look at Precision Dual Sensor Systems:


Back in October I took a look at the upcoming Precision Dual Sensor.  It was a simple (and rather short) test ride, mostly to validate it exists, and how well it tracked against a few other power meters.

You can find details on that in this post here, which talked through everything from the basics to the data on the test ride.

My review here (the one you’re reading) is focused exclusively on the single-leg unit.  Once the ‘other half’ of the system, the right leg, starts shipping – then I’ll likely release/do a new review focused on the full left/right system.  The expectation is that such a system will be simply a case of adding the drive-side crank setup to the existing left-only crank arm.  Thereby allowing for easy upgrades.

4iiii has not released a timeframe for when that’ll occur, thus, I don’t have a dual-leg system at this time and am therefore not working on a review currently for such a system…because again, I don’t have it yet.

Power Meter Recommendations:


Note that while this is a power meter review, I tend not to put purchasing recommendations/comparisons to the rest of the market in these.  The reason being simply that I’ve created an entire post dedicated to that – with boat loads of information about all the options available on the market.

Now – what about comparing between the different left-only options?  Well, at a high level I’d focus on compatibility first.  Eliminate those crank arms that won’t mate with your bike (or your crank arm religious beliefs).  All of the various left-only units have nuances in terms of compatibilities, so that’s the first step.  The next is looking at price.  Right now, the 4iiii Precision is the least expensive out there (simple fact), with Stages closely behind it at about a $129 premium.  Finally, consider whether you plan to upgrade to a dual-sensor system down the road.  If that’s the case, you’d want to narrow down to: 4iiii, Pioneer, Garmin, Polar, bePRO.  All of which offer currently shipping options that allow you to ‘upgrade’ to a dual-left/right system down the road.  But, let’s not get so far ahead of ourselves, read the buyer’s guide post first.

So grab a cup of your favorite caffeinated beverage and swing on over to that guide for more than you ever wanted to know.



There are so many variables and parameters to consider when choosing a power meter.  I’ve discussed all of those in the aforementioned buyer’s guide.

That said, once you have narrowed down your selections, the current 4iiii Precision is a solid left-only option.  I’m especially interested to see how things look once they layer in the right-side of the equation next year.  If they can maintain the same level of accuracy they have now, and still hit the same price ranges as previously advertised ($749), it’ll be one of the cheaper full left-right capable options (with only WatTeam being cheaper).

Until then, it takes the KOM for the least expensive direct force power meter on the market – and one that’s just as accurate and easy to use as ones that cost significantly more.

Found this review useful?  Or just wanna save 10%?  Read on!

Hopefully you found this review useful.  At the end of the day, I’m an athlete just like you looking for the most detail possible on a new purchase – so my review is written from the standpoint of how I used the device.  The reviews generally take a lot of hours to put together, so it’s a fair bit of work (and labor of love).  As you probably noticed by looking below, I also take time to answer all the questions posted in the comments – and there’s quite a bit of detail in there as well.

I’ve partnered with the retailers below. Any shopping done through those links helps support this website. Thanks!

4iiii Precision Power Meter – Amazon

For European/Australian/New Zealand readers, you can also pick up the unit via Wiggle at the links below, which helps support the site too! With Wiggle new customers get 10GBP (or equivalent in other currencies) off their first order for anything over 50GBP by using code [Currently Disabled] at check-out after clicking the links below.

4iiii Precision Power Meter (EU/UK/AU/NZ – Wiggle)

Thanks for reading!  And as always, feel free to post comments or questions in the comments section below, I’ll be happy to try and answer them as quickly as possible.  And lastly, if you felt this review was useful – I always appreciate feedback in the comments below.  Thanks!

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  1. Brandan K.

    Did you do any testing with this unit and the Garmin Fenix 3? I’m curious how reliably it communicates with wrist worn units. Thanks!

    • A little bit with the FR920XT and Epix, but I don’t think I have any Fenix3 data. I didn’t see any issues, but my testing with wrist units wasn’t as wide as my testing with Edge units.

    • Brandan K.

      Thanks Ray. I believe the Fenix 3 and the 920xt share the same ANT+ antenna, so my guess is that they would function similarly. I sold my Stages unit since I was not able to get it to communicate reliably with my 920xt or my Fenix 3. Perhaps 4iiii has better signal strength from their pod. I think it might be worth trying.

    • Hi Brandan. You shouldn’t have any problems with a Fenix 3.

  2. Patrick

    Don’t forget to attach the pre-load cap before tightening those two bolts on the crank arm!

    Thanks for another awesome review!

  3. rjdennis

    any news on the self install option?

  4. Simen

    Great review! Thanks.

    I’m debating wheter I should buy a power meter or not, and this seems like a great option for a reasonable price. However, I wish I did not have to send my crank arm in. Shipping from Europe to USA for installation and then back would take weeks.

    And Ray, did you do any testing in the rain? How much rain can it handle? Do I need to be careful when washing my bike?

  5. Gergely Szatmari

    Hi Ray!
    Did, will you have time to test the powermeter with Polar V800?

    • No, I didn’t.

      Just as a bit of background, part of the challenge I have with testing multiple BLE devices is that it’s basically one device per ride, since the max concurrent connection on BLE is one. That said, I’ll make a game-time decision for tomorrow’s ride and do it either on V800 or V650.

    • Garry Curley

      That would be great!

      Cheers Ray

  6. Toni

    Hi Ray – are there any access issues with changing the battery? Presumably you can do it easily enough without having to take the crank arm off every time?

    • Richard W

      Toni, It takes about 20 seconds to change batteries. I have a gen 1 usnit and all you have to do is twist the cap about 1/2 cm from “locked” to “unlocked,” pop out the the old battery , put in the new and twist the cap back on. Finis!

  7. How does it compare to the Limits… ;)

  8. M Velo

    Hi Ray,

    Is the 4iiii Precision Power Meter compatible with 2013 Madone frameset?

    I am well aware that a power meter like stages won’t run on the Madone unless I replace the Shimano rear brake with the Bontrager. But the size of the 4iiii precision power meter makes me a little curious and it would be great if you could throw some light on this case.

    • Drop us an email to support@4iiii.com. We’ve managed to fit a a few Madones so far. It depends on a few variables though.

    • S. Smith

      One of the reasons I chose the 4iiii was due to nearly zero clearance between my DA crank arm and the Trek Emonda SLR chainstay (Stages didn’t have a chance). Being able to specify the 4iiii location (to some degree) on the crank arm saved the day.

    • M Velo

      Hi Karel,

      The issue is the brakes which are installed underneath the Bottom bracket and not with Frame.

      Were those bikes(Madone) equipped with Shimano Brakes or with the Bontrager brakes?

      I will be using a 7900 crank arm if I plan to purchase your power meter.

    • We’ve installed with the Shimano brakes before. The 7900 crank arm complicates things though – due to it’s shape we have less latitude with the installation location.

  9. Sam

    Was waiting on a final review, with that I just purchased using the code, thanks!

  10. Hide

    Now only for the Canadian dollar to improve – shame it’s a Canadian company and ships from Alberta… At least there will be no import fees

    • Lee

      Ya, I was hoping there would be some kind of break for Canadian customers ($399 Canadian) Dollar took a turn and it’s starts making these reasonably priced power meters expensive again.

    • Roman

      The fact that Canadian company does not offer Canadian dollar priced product is putting off my buying this power meter.

    • Lee

      This bothered me as well since the dollar is at 1.4.

    • Rob

      I have to echo these concerns. Really disappointed the company won’t help out its Canadian support base by taking into consideration our dollar. To me it represents an opportunity for them to gather some momentum here in Canada as most are reluctant to buy anything from the states these days.

    • Lee

      I ended up purchasing mid December, not paying attention to much to the exchange rate. Even after receiving a 10% discount my final cost was $597 Canadian. Last year with the exchange it would have been about $450.

    • Support 4iiii Innovations

      Our order screen allows you to select your currency so you can see the price at the current exchange rate. As we primarily operate in a global market, we are maintaining the single price structure in US currency.

  11. Tosin

    So, I’m assuming once it’s on, it’s not coming off? So if you are changing bikes in the future, you either sell it with the bike, or you keep the drivetrain?

  12. Dan Vu Quoc

    The literature for precision and your old article used to mention temperature compensation, do they just simply not have this anymore?

    • PRECISION was designed to maintain a high level of accuracy across a range of temperatures. Should we find that additional compensation mechanisms are necessary, we will address that need through a future firmware revision. We continue to recommend that riders re-zero PRECISION before every ride.

  13. Dan Morley

    I have had no dropouts from my Precision to my wrist worn or bar mounted Garmin 920XT,

    I have updated my Precision to the newest firmware but my Precision readings are still around 30 watt (AVG and NP) less than my Kickr reads. I have no other PM to compare it to. I guess the only option is to apply an offset to the Precision. I thought the readings would be closer.

    Ray, do you ever compare PM reading to Kickr readings?

  14. Chris

    Are the newer units different from those made earlier this year? Was lead to believe that the change for your pedaling style was strictly firmware change and not hardware. Would love to here from Karel of 4iii on this. Like you said if you only have one power meter how do you know if you have an accuracy problem.

    • If you only have one power meter why do you care? The number is irrelevant as long as it consistently goes up and down for the same inputs. If you’re using the same device to train and race then the exact wattage makes no difference whatsoever. if your peak is 100 then 50% of that is 50. If your peak is 400 then 50% of that is 200. This means that whatever the number you can work out your zones and FTP, and because you can do those things the power meter will fulfil its destiny.

      If you get wildly fluctuating readings for the same input then that’s a huge problem of course.

      That’s assuming you’re using it to train and/or race of course. Data collection for geeky reasons is a different matter, but then that would put you in the same box as Ray and you should have at least 17 power meters to test and compare with :)

    • The problem becomes that someday (whether next year or three years from now), you go out and upgrade your power meter to something new. At that point, all past power data gets thrown out the window, because it’s not accurate (potentially by a lot – like 10-20% in my case).

      And because technology is technology, there’s virtually no scenario where down the road you won’t upgrade to something new – hence why it’s so important to be accurate.

    • Very good point Ray, hadn’t thought of that. The next question though, is if there was something available for silly cheap that measured power consistently but with different numbers could you ignore it then? I was thinking this with the power meter box company (they proved they have a box…). Even if it’s rubbish, at the price consistency would still allow it to be a useful training tool. As you say, eventually you’d have to bin the data but I think I’d be OK with that as a trade off to keep $1000 in the mean time. Then I’d go on forums and moan about accuracy :)

    • The difference between Ray’s original units and the one he has now is a combination of firmware and installation method. The hardware in Ray’s new crank is the same as the others, but we’ve made some changes in our manufacturing process that remove style dependencies. First generation PRECISION units have the potential to exhibit similar behaviour to Ray’s original PRECISION based on your riding style. We have found this riding style to exist in a very small subset of riders. Those with a second power meter, who know approximately what the difference is between it and their PRECISION are invited to use the scale factor feature that we included with the latest firmware release. The intent of this feature was to allow customers with known L/R leg imbalances to correct for them, but the feature can also be used to align PRECISION with your other training tools so that you can transition seamlessly between them.

    • Stephane D

      Hello Karel, Hi Ray and many thanks for your work.
      The scale factor is a very interesting feature, which could influence my choice for a second powermeter.
      To align PRECISION along with a powertap, one use the smartphone 4iiii app.
      I’m wondering if the aligned power numbers are only computed by the 4iiii app, or if they also could be read by an other head unit (like garmin 920xt).
      Thank you.

    • Hi Stephane,

      You set the scale factor with our app, but then the adjusted values are transmitted by Bluetooth and ANT+ from the power meter, so you can receive them with the head unit or app of your choice.


    • Stephane D

      Hi Karel,
      Thank you for the explanation. Very good feature.
      Kind regards

  15. Oscar

    Can I just say I am in total awe of how clean your bike’s frame is, considering it’s mileage and color. I guess I should do a total teardown/clean of my white bike on the weekend now.

    • portemat

      My thoughts exactly!
      Not sure if it is a good thing, that after reading the review all I can think of is “how clean is that bike?!”

      I think we get spoilt here, and a high quality review is expected, so we end up looking for something else!!

    • Trust me, it’s an optical illusion. The white frame looks like crap in person. But with photos, the whites ‘blow out’ the picture, so you can’t see the scratches/marks on it.

      I’ll never purchase another white frame.

    • Gunnar

      That white Cervelo is to Ray like a Hofner Bass is to Paul McCartney or a cane to Charlie Chaplin. He can never get rid of it.

  16. Adam B.

    Thanks for the review. Is there a general turn-around time on getting your crank arm back in the US?

    • John

      Once the arrangements were made, it took me a week from when I dropped the package off at the FedEx office until I had it back in my hands. The 4iiii’s folks were awesome.

  17. Alex

    You stated in this review that it makes sense that the P1 pedals were higher than the 4iii because it’s closer to the source of power (your legs). But on one of the charts above the PowerTap G3 had the highest average!

    • Welcome to the fun world of power meter testing. The more I do it, the more variances you see. I always find it funny when certain groups of folks vehemently argue over the accuracy of just a few watts. Seriously, if ones knew how much their power meters differed week after week (all brands, yes, including SRM), they’d probably be amazed and give up.

  18. Mark

    Any time frame on compatibility with carbon crank arms(ie Sram Red)?

  19. Lumanz

    I’m really happy with my Precision, reliable and constant. Looking forward to the other half. Maybe a discount for the early adopters? Or a discount on the crankset when buying from 4iiii wound be nice!

  20. FJ

    Like, really like it, but I’ll wait for the dual sided version

    To 4iiii, if you do manage to get the dual sided option for $750 and it proves accurate and reliable, you’ll be in the running for my next power meter. As of today, the only candidate is Power2Max, for the simple reason that it’s solid, reliable, and keenly priced (wish I could say the same about my powertap)

  21. Stephen Spall

    Have had the unit since July and very pleased with its performance, no issues and seems to be consistent. The review above would have benefitted with a comparison with the Stages Left only power meter as I suspect potentially buyers coming in at the lower price point would view these 2 as the main options?

    • Seth

      Don’t think it would have been possible to compare this to Stages as the stages is measured from a dedicated left crank arm while so is the Precision. From what I can tell, you can’t run a Stages and a 4iii Precision at the same time.

    • Correct, they occupy the same space on a crank.

      From a technical standpoint, they’re pretty much identical. There are some minor feature nuances, but those tiny differences between the two are actually two features that I believe are useless on a left-only crank.

      A) Stages has high-speed data analysis: Realistically, at high-sprint levels, we’ve seen so much left/right inbalance that this number isn’t terribly useful.
      B) Meanwhile, 4iiii has Torque Effectiveness & Pedal Smoothness: Which, like Stages is somewhat useless as a left only metric.

      Beyond that, they both have dual ANT+/BLE. Really, it’s going to come down to crank compatibility (which Stages has a slight edge on with now carbon), as well as price (which 4iiii has an edge on).

      In other words, it’s all kinda a wash technically.

  22. Thomas Bunge

    Hello DC,
    I’ve been waiting for this post for a long time. The 4iiii solution seems to be ideal for me and I even was in contact already with Karel from 4 iiii support….BUT, and that’s my biggest concern, Karel wrote me, that if I wanna buy the system, I would have to send them my crank to get it modified. I’m using my bike quiet often and I can’t wait weeks to get back my crank. Not to talk about shipping costs to Canada and back. Any ideas/words on that?

    • Julian Simpson

      Someone above mentioned that Precision is actually in Canada (Alberta)

    • Julian Simpson

      Sorry I misread your comment and assumed you were in Canada.

      That said someone above said it took about a week from the US to send and receive their crank including installation.

    • Thomas Bunge

      No, I’m from Germany. Sorry, didn’t see the post you are mentioning.Shipping to Canada and back is insane expensive, so I’ll have to check on that.

    • FJ

      Check with 4iiii. I think they may have an office in Frankfurt. One of my riding buddies was working there for them, although not any more and I’m not sure if they just closed the office or he decided to move on

    • Hey I’m from Germany and we had no problems ordering from here .
      They sent you a simple box and all you have to do is to carry it to the post office. done.

    • Thomas Bunge

      @Alexander, can you send me a PM about the process, costs, customs etc., please? Thanks (bungee13@web.de)

  23. andrew

    Well, this is very vain, but why do they leave the wings on the unit once it is attached to the crank? The unit cannot be removed and then put on another crank, so once installed their utility is gone. However, they just look awkward. In fact, they look so awkward that I would almost consider the Stages Cannondale SiSL instead of the 4iiii just because it has such a cleaner look.

    Is there any reason why one could / should not file down or shave off the wings once installed? Could it hurt the performance or accuracy of the unit?

    • Steven Shaw

      I wondered the same about the wings. Would there would be an issue if you took a Dremmel to them?

      This has now become the powermeter that interests me most. Only trouble is I live in the UK. I think I will hang on for news for a self install.

    • Carl

      I had the same thought before I got mine, but I never notice them.

    • Daniel G

      Stages doesn’t put a power meter on the SISL nor the SISL2, only the SI. So if you’re vain enough to care about the wings on the Precision unit, you probably also care about the crank saying “SI” vs “SISL” or “SISL2”. Vanity aside, you might also care about the differences in material & construction of the SI vs your SISL, if any.

  24. Michael

    Hi Ray,

    Thanks for the (as usual) great review. I’ve noticed that both this and your Infocrank review your accuracy results compare to a suite of PowerTap products. Any concern that it’s potentially “not fair” to have most of the comparison units come from the same manufacturer? My thinking is just that PowerTap probably uses similar testing/calibration/QA/etc processes across their product line, making them more likely 1) agree and 2) react similarly to variable conditions. I know you have good reasons for selecting each of these PMs (the G3 is the only hub-based unit, you like the P1’s better than Vector/bePRO for general use, Quarq/P2M aren’t compatible with Shimano crankarms, etc..), and that each have been tested thoroughly, but it seems like variety could be beneficial (and hopefully not too much more work for you?).

    • I’m constantly mixing and matching power meters, so while this was a random case of having 3 PT units vs one 1 4iiii unit, there’s many cases of 2PT vs 2 others, and so on.

      In this case, the test was merely a cause/effect of working on both reviews at once. And, due to process of bottom bracket and crank elimination, it’s just the combo I came up with. The following factors resulted in that:

      A) My Quarq are 175mm, and uses a different BB standard, the 4iiii unit was 172.5 – you can’t mix non-Vector units and get a scale factor option to correct lengths (which would impact roughly 2%)
      B) I couldn’t use the Verve Infocrank, since that’s a self-contained system and isn’t compatible with 4iiii
      C) I couldn’t use a Pioneer, for the same reasons as Verve.
      D) I could have used Vector2 instead of the P1’s, but that’s such a pain in the ass, especially as I was moving pedals around between two bikes for other tests.
      E) The bolt pattern of the C1 didn’t match my other units/wasn’t compatible
      F) The bePRO was on another bike and headed back to them.
      G) Power2Max was setup for ROTOR cranks, which aren’t 4iiii compatible.

      All that said, I’m always mixing and matching. Come this weekend I’ll be ‘re-stacking’ that bike a bit, deciding exactly on how I’ll mix it up for tests from Christmas forward, roughly it’ll probably be:

      A) Wheel: PowerTap G3 Hub
      B) Pedals: Likely P1, but may swap in Vector2 for a short bit
      C) Crank Spider: Might buy the Quarq RIKEN AL (need non-carbon for WatTeam)
      D) Left Crank Arm: 4iiii Precision or Stages
      E) Crank Arm Pods: WatTeam
      F) Other: PowerPod

      The challenge is setting up such a bike requires a fair bit of validation on all the pieces, such as bottom brackets, carbon aspects, crank lengths, etc… to make it all match.

  25. Emmanu

    Does it match in bluetooth with suunto ambit 3 peak ?
    Tx for answer (&the review)

  26. Maureen O'Connor

    Can you tell me when the Garmin Forerunner 235 GPS watch will be available? Garmin can’t give me any info other than it is “top secret”! It is my husband’s Christmas gift! I’d hate to be empty gifting!

  27. Karl

    thank you for that review and partnering with Clever Training. So I could afford express international shipping to Austria without additional cost :-)

    • Javier

      Hello Karl,

      I live in Spain (European Union too). Did you have to pay custom taxes or the likes? What process did you do?


  28. Marvin

    Hi Ray,

    Any ideas if they will be selling in Europe? And if so when that will be.
    With the customs and all it’s for europeans better to go for stages money wise.

  29. Dale

    Looks from your picture of the dual sided 4iiii, there is a small pod nested in the chainrings. Is this how they plan to release the dual sided unit?

    I’m looking for a dual sided (actual, not estimated) power meter that doesn’t have any attachments to the chainrings so that I can easily clean the chainrings along with my chains and cogs. I don’t use Look pedals so P1 and Vector are out. I use Speedplay but doesn’t look like Brim Brothers is out yet and not sure if they would be compatible with my Tri shoes anyways. Watt team Powerbeat was the only one I found that does what I describe but I’m not so sure about their quality and the looks aren’t so good. The one I was hoping would work was 4iiii dual sided but if they have a pod nested in the chainring, it could be a dealbreaker for me. Any suggestions that match what I’m looking for? I went through your Power meter buyer guide 2015 but didn’t find one yet.

    • Being a prototype, things may well change on the pod style/design/placement – so do keep that in mind.

      Another one to check out on your list (which seems fairly complete) is bePRO, but that’s basically in the same boat as the P1.

      I’d agree that the best bet for you seems to be the WatTeam, once they release.

    • Hello Dale,

      Our right-sided power meters are not yet available and none of the details are finalized yet. On the prototype to which you’re referring, the visible piece is a battery compartment. The chainrings are still removable since there is nothing attached to them.

  30. Christopher

    Ray I am being told by 4iiii that the Garmin Edge 800 does not support the Torque Effectiveness or Pedal Smoothness metrics. Do you know or think that Garmin would add this in a firmware update at some point or are they done with updating an older model? Thanks

  31. Earnest Slusser

    Christmas is in the single digit days away. I’m still analyzing over the pros and cons of this and Stages.

    So…to help me, is the 10% discount still available and for how long?

    Thank you Much,

    Roanoke, Va Tri Club member

  32. Aleksandr

    It would be great if they will sell crank arms with already mounted powermeter.
    I can`t even imagine how much time can it take to send my crank arm from Russia to USA and after a week of installing they will send it back. ~3 weeks or maybe a month without a bike…
    Their support says you can buy new crank arm and send it to us, this situation is better of course, but it is even more funny – anyway i`ll buy left crank arm in USA the seller will send it to russia, i will send it back to USA to 4iii, they will send it back again – Profit ).
    Cmon 4iii i can pay to you for the crank arm, buy it for me and install your powermeter and send it to me!
    Take my money !!!

    • Not to worry, shipping and installation is relatively quick: 2-3 days shipping each way and 2-3 days installation so you wouln’t be without your bike for long. If you still want to get a crank from the USA you can have it sent directly to our factory in Canada for installation. Please contact support@4iiii.com and we will get this sorted out for you.

    • Aleksandr

      I send you email.
      But after it, i saw on your site, that i`ll pay 100$ for shipping from your site. it is 500$ with powermeter.
      link to i.imgur.com

      The link to clevertraining.com suggest 30$ shipping. So the total bill will be 390$ (with dcrainmaker discount code).

      link to i.imgur.com

      At this moment their price $110 lower, than yours. I do not lie, screenshots attached.

      So i think i`ll try to contact them too, maybe they can help, and i can order the crank for their address.

  33. Aleksandr

    Do not be shy to write questions to 4iiii support. They are always ready to help you.
    I`ve got so many questions about shipping, pricing, installing, payment and many other, I sent them tons of emails… They were so kind and so patient to answer all this stuff, which by the way was written on my bad English, so i can`t not to say about it here.

  34. T. Fuller

    I think this is an ideal set up for my son who is a Jr. racer at the age of 14. I’m not as interested in accuracy with him as I am with setting training parameters with him using power. Any thoughts or suggestions?

    • Hmm, honestly, I’d look at the PowerCal. It’s probably a great introduction to what power is, at a fraction of the price – especially if you’re not super-concerned about accuracy.

  35. JR

    What software are you using to make those compare charts?

  36. Joe

    Hi Ray,
    great review! I have two 4iiii units in use and I am pretty satisfied.
    The one thing I noticed is a drift on the calibration. In more detail, I checked in the bike at a long distance triathlon on Saturday and calibrated the unit just before. On race morning you obviously can’t go for a calibration ride again… In the race I saw a gap of about -30Watts to what I normally produce, taking into consideration my heart rate and RPE. Since I am quite an experienced rider I am pretty sure there was something wrong with the calibration. But I normally don’t stop in a race to fix electronic issue things….
    Have you seen anything similar, means any major differences in the 2 calibration parameters when you recalibrate or drifts?
    Best, Joe

    • Pearl

      Hello Joe

      Is this occurring with both your PRECISION units?
      It appears that you need to restore your factory calibration. Use the 4iiii app, connect to your PRECISION, go to the advanced settings screen and select restore. While you are in the app, please check that you have the latest firmware installed (0.3.0) and upgrade if required. Please send your zero offset values to support@4iiii.com.

  37. Karl

    I have sent it to 4iiii on December 18 from Austria and received it today with installed PM!

  38. Seth

    Been agonizing over whether to go with this PM or wait for the Watteam PowerBeat. However, in light of their newest delay and this glowing review; and the fact that I’m a relative beginner cycler, I’m thinking the Precision may be the way to go. Seems like I won’t be missing anything having only left leg data. Anything I’m missing or should be considering?

  39. Craig

    Interesting …. they are providing PrecisionPro units to Team Quickstep:
    link to 4iiii.com
    “Through a partnership with the team’s official equipment supplier, Specialized Bicycle Components, 4iiii is providing dual-sided PRECISION PRO power meters to the team’s more than 30 world-class riders.”

    but from their facebook page re: the press release:
    “PRECISION PRO is a pre-lease dual power meter based on the same core technology as PRECISION. We will post the dates for a dual power meter when a commercially available offering is formally announced. Right now, all we can say is that the dual power meter remains on our strategic road map.”

  40. Ted Thibault

    Your review of the 4iiii made my choice easy. Precision was very responsive in their turnaround time. The unit worked with one small issue. The cap that allows battery changes can be put on in two orientations, 180 degree turn. In one position the unit would not pair. Emailed Precision and got an immediate response and suggestions to correct the problem. Nothing seemed to work. So I suggested that they send me another cap. I would pay for it. Not only did they send me TWO caps but overnighted them to me via FedEx. I ended up shimming one side slightly and this has solved the problem. My point is if one is hesitant to order this product because of support issues, Id like to say that this is the best support I have ever received. Issues arises with any product. Its how a company responds that makes the difference. The 4iiii works! And I ordered it through Clever Training. Thanks Ray.

    • Karl

      I just can confirm the experiance from Ted! Every single email to the support team was answered latest next working day!

      I’m very confitent that i choosed the right PM

  41. Lee

    I agree with both. Every question whether via email or their Facebook page (via messenger) were answered within hours.

  42. seth

    What does one do about zeroing during a race? Do you just take care of it prior to the swim start?

  43. jay d

    I was intrigued by the review and price. But if a canadian company can’t support a canadian rider with some price adjustment…….

  44. Stephen

    OK, this may be a bit premature–there is some data I’m missing and will collect soon, but it’s the weekend and I thought I would post some questions/concern here in hopes that I might get some feedback before contacting 4iiii on Monday.

    I’m thiiiiisss close to purchasing my first power meter and after lots of research and going back and forth with various options, I was ready to pull the trigger on a Stages as the best value for me at this time. I had ruled out the Precision earlier in the process because I could find very little feedback about it’s actual use in the real world and I had a couple of less-than-optimal (but nothing serious) email exchanges quite some time ago when trying to get info on another 4iiii product. And, of course, Ray’s first experiences with the Precision didn’t bolster my confidence. I always thought the notion that Ray (of ALL PEOPLE) would have some kind of “unusual” pedaling style that would skew the accuracy of the power meter was kind of far-fetched. To be frank, I still think this is kind of weird, but Ray seems to be satisfied, so I’ll go with the flow on that.

    This current review has pretty much turned me around and now I’m ready to just go with the Precision, IF I can verify that it will, indeed, work on my bike. My main reasons are that the Precision is less expensive by enough to make it a better monetary value and, perhaps more importantly, it really looks like the option to add right-side measurements will happen sooner or later.

    So, with regards to compatibility: I have a 2015 Trek Domane with a Shimano 105 (5800/11-speed) group, EXCEPT for the crankset. Trek cheaped out and put an RS 500 crankset on the bike. When I researched this for compatibility with a Stages PM, I was assured by several different sources that I could buy a 105 5800, Ultegra 6800 or an Dura Ace 9000 crank arm from Stages and it would just bolt right onto the RS 5000 spindle. It has the same type “clamp” attachment and I was assured by Stages and other users who had successfully put the (mismatched) crank arm on the RS 500. So, I was going to get the Ultegra, put it on and then watch for a good sale on a full Ultegra 6800 crank and get everything matched up again.

    I want to do essentially the same thing with the Precision. I’ve been told by 4iiii (via email earlier today) that they have successfully fitted the Precision to Trek Domane’s in the past, but to be sure I need to do some tests, take some pictures and/or make some measurements and send to them to be sure. AND (bonus info!) 4iiii is now offering a Stages-like option to purchase the crank arm from them—so one-stop shopping makes this an even more appealing proposition.

    Before actually plunking down my $400 (less 10% at Clever Training????), I’d like to be as sure as I can that I’m not overlooking anything.

    Has anyone here done this install–to a Trek Domane with BB90 bottom bracket shell? From pictures I’ve seen and from others who have switched 105, 6800 left arms onto the RS 500 crank, it looks like, if anything the higher-lever arms would have even more clearance (i.e., be a bit slimmer) that the RS500. Per 4iiii’s videos, I’ve tried sliding an AAA battery (10mm diameter) between the crank arm and the seat stay/frame. It seems to make it to a point about the same as where the photographs of Precisions mounted to Shimano arms are, but I obviously need to be sure.

    One other question regards the app or device needed to do firmware updates. PLEASE don’t tell me you need an iOS device!

    Thanks in advance for any pointers, advice. It would be great if someone has already done this and can vouch for the process.


    • Pearl

      Hello Stephen

      You are not restricted to iOS. Our 4iiii app is designed for both Android and iOS.

    • Stephen

      Thanks, Pearl.

      Right after I posted the above a complete, super-low-mileage 6800 crank-set in the size I wanted showed up, so in a day or two I’ll have that available to send in.

      I’ll contact you via the 4iiii website with more detailed questions on how to best proceed–whether or not you can install the Precision from a set of measurements with the RS500 crank installed, or whether I’ll have to put the left arm from the Ultegra crank on the bike for pix and measurements. Any chance you guys have a template or measurements from previous Trek Domane + 6800 installs?


    • Pearl

      Hi Stephen

      We have installed on that combination many times. Normally we would request these clearance diagram be completed but I will forward you one of our completed installations for review when you place the order.

  45. Seth

    Just an FYI to anybody considering a purchase- they are backed up on installations. What I had expected of 1 week turnaround is looking like at least 2 weeks.

    • Philip

      Aren’t they just glueing the sensor to a crank arm overnight and shipping them back out? How do you get backed up 2 weeks?

    • They also do a bit of testing prior to sending it out.

      But either way, backups typically happen when order exceed workers to handle them. In most cases, those tend to work themselves back out again. It wouldn’t surprise me (given that comment was in late January), if that was a result of various holiday stuff from Decembe.r

    • Pearl

      Good news! Our manufacturing team is growing so we can fulfill your orders more quickly. We’ll be through our current backlog by the end of next week. Turn around time in the factory for a left side installation is five business days. When you place your order, select the shipping method that best meets your timeline. You can contact our sales order team for more information: sales@4iiii.com.

  46. Stephen

    I was ready to just go with Stages, and still think it’s a good choice, but when Ray’s in-depth review came out, I thought that the cheaper initial cost and the probability that a dual-sided upgrade will be available at some point warranted choosing the Precision.

    4iiii’s website is touting their sponsorship of the TdF Etixx/Quick-Step team (link to 4iiii.com ) so there is definitely a dual-sided version out there.

    Before ordering the Precision (through Clever Training, of course…) I checked with 4iiii’s customer support on when we might reasonable expect to hear something about the dual-sided upgrade. The response I got was that backward-compatibility has not yet been decided, so that’s a little disappointing, especially since dual-sided “upgrades” were always promoted by 4iiii itself. I understand that further development may have revealed technical difficulties in offering backward compatibility, and I don’t have any idea whether left side components being used on the Etixx/Quick Step units are the same as the ones being installed on consumer’s cranks. The Etixx/QS units are also installed on DA-9000 cranks, but they certainly look dimensionally identical to 6800, or even 5800 cranks to my eye….who knows?

    If there is any real possibility that units purchased now will not be upgrade-able, I’ll have to rethink and decide whether to just be happy with single-sided power to get started with, or re-consider something like the bePro or P1 pedals.

    Ray, please keep us posted if you can get any confirmation on this upgrade issue–one way or the other!


    I scored a very low-mileage Ultegra 6800 crankset from eBay and test-fitted to my bike and

    • Stephen

      Sorry for the dangling half-sentence in the post….wish there were a way to edit one’s comments!


    • Lee

      I sure hope it’s compatible! I wouldn’t have bought the left side only, knowing the right side would not work in conjunction with the left to make a dual side system.

    • Hmm…I hadn’t thought about it, but I think I may be able to turn on comment editing for registered users. Let me do some poking.

    • Stephen


      Thanks. Along the same line, is there any way to get the URL for a SPECIFIC comment so one could link to it when posting to other sites? Ever thought about hosting a set of forums as part of the site, using vBulletin–much more friendly for handling threaded discussions. But I realize that might be opening a whole ‘nother can of worms and there might not really be much in it for your site. I think you must be pushing WordPress to its max already with the complexity and amount of content you’ve produced. Much appreciated.

      Oh, and please see if you can get 4iiii to make a decision on the backward-compatibility issue. It’s stopped me dead in my tracks after finally arriving at a choice! I’m sure there are others out there who are EXPECTING a dual-sided upgrade who would or will be plenty steamed when they announce a dual-sided option that won’t work with early-adopters units.


    • Yup, to share a specific comment, just right click and copy the shortcut to a given timestamp in the comment (just below the commenters name). That ensures it always links back to that exact comment (even if the public comment number changes).

      I have looked at forums, but right now I think that’d be biting off more things to try and track and keep on top of (and I’d suspect that folks would naturally expect I’d monitor those too). Makes it tough.

    • Stephen

      Thanks, Ray. Got on getting a link to specific comments.

      Yeah, I think forums would probably be something of a dilution of “Ray-generated” content and I don’t know how you keep up with updating your own articles/posts let alone monitoring handling all the user questions and comments. And how you did all this before “retiring” is almost inconceivable.


  47. John

    Not sure that I’m digging those protrusions on both sides of the sensor, it almost looks like something designed to be attached with Garmin bands for universal mounts (though obviously that’s not the case here). I’m positive those would catch on some underbrush or small branches on my gravel bike in short order.

    One of the guys at gravelcyclist.com got pics of the dual-sided version being tested by Ettix Quick-Step, where the left side is sensor has a much lower profile (ala Stages), I think I’d be much more inclined to wait for that version:

  48. Bernd

    Oval Chainrings

    Hi Ray & Karel,

    I havent heard anything about oval chainring compatibility for some months and i´m wondering if there are some news. (I use the 10% ovals from Rotor, not those almost rectangular ones ;))
    Does anyone know if the new software can handle this?
    Additionally i would like to know if the resulting error is constant, if so, it may be possible to correct it by adjusting the l/r balance. I am not keen on perfect accuracy, i just want to know if i can get reliable data while using oval chainrings.

    Kind regards,

  49. seth

    Just updated the firmware this morning to 0.4 and now the unit will not connect or pair to either myphone or computer. It then prompted me to upgrade to 0.5 and it won’t connect long enough to do the upgrade. ANy ideas?

  50. Aaron

    Anyone ordered this through Clever Training? How does it work? Does CT handle the logistics, or will 4iii contact me to work out the logistics, or… ?

    • Daniel

      CT will send the order to 4iiii on Tuesday (I believe). Then 4iiii will reach out to find out your crank model & bike info within a day or so. Or at least that’s what happened when I ordered a few weeks ago. I sent my crank arm in a week ago and am waiting to hear back from 4iiii.

    • seth

      That’s exaclty how it happened for me. I bought in January. I bought on a Friday night and 4iii reached out to me by Wednesday. I had the crank sent in by Friday. Installation took about 2 weeks (which was longer than expected).

    • Daniel

      4iiii is running a couple weeks slower now.

      Here’s my timeline:

      – 3/4 at midnight – Ordered through clevertraining
      – 3/9 received an email from 4iiii: We received your order from Clever Training. Please provide your crank model so I can advise you when we will be installing PRECISION on your left crank arm.
      – 3/9 a few hours later, received this email: Thank you for the information. Your installation is scheduled for the week of April 11.
      – 3/24 Received a fedex shipping label via email. I emailed 4iiii to ask if I should ship it in now or wait for 4/11. They said ship it now.
      – 3/27 (holiday Sunday) I dropped it off to local fedex, but it sat there for 20ish hours until the next pickup.
      – 3/29 tracking showed it was delivered ~ 11 AM

      That’s where my timeline ends, but I’m expecting to receive a return shipping # any day now. They estimated 3-4 business days in the ‘shipping your crank’ pdf they sent on 3/9.
      Its cool they’re running ahead of schedule. But please note their website currently says “Order now and receive PRECISION in 2-3 weeks.”

    • Aaron

      Thanks for the info, folks!

      I’m going to order through CT.

    • Aaron

      Done! Can’t beat $359.99…

    • Thanks for the support Aaron (and Daniel & Seth)!

    • Aaron

      Happy to do it. Very much appreciate the work that goes into each of these reviews. I’m exhausted just reading through them :-)

      I’ve also started buying all my random stuff off of Amazon through your link. The monthly summary they send you is about to get… weird.

  51. Andrew

    I use an Ultegra 6800 crank connected to a bb30 via an adapter (WheelsMfg). Would this have any effect on the power meter? Very close to purchasing off Clever Training. Just making sure to dot my T’s and cross my I’s.

    • Hello Andrew,

      You’ll be fine with this setup, there should be no issues.


    • Andrew

      Hi Karel,

      How does the order process typically work between 4iiii and Clever Training? It has been a week (ordered 04/05) and I haven’t received any correspondence. I understand this is probably a busy season for power meters, just poking for information.

    • Hi Andrew-

      Sorry, someone else had asked this, and I meant to loop back with a more detailed answer. Essentially Clever Training and 4iiii work in batches on a weekly basis, as it’s what they’ve found is the most streamlined manner. CT sends the batches to 4iiii every Tuesday, and then 4iiii takes it from there. I suspect that you might have just ordered a few hours after the batch e-mail occurred, so you’d be in today’s. Typically 4iiii then e-mails the buyer within 1-2 business days, and from there it’s just logistics of shipping cranks/labels/etc…

      Generally speaking, the entire process takes 2-3 weeks from the moment the purchase button is pressed until you’ve got the cranks back on your bike and are pedaling – depending on the queue at 4iiii’s.

      Thanks for the support!

    • Andrew

      Much appreciated. I figured it was something of that sort. Amazon Prime has killed off the ability to wait patiently for anything.

    • Aaron

      I asked this question about 10 days ago.

      I ordered from Clever Training on Monday 4/4 and heard from Precision on Friday 4/8. Install is scheduled for “week of 4/18”.

  52. Richard noble


    Has anyone had issues using the 4iiii in tough winter conditions, heavy rain, salt etc. Just wondering if there are any issues such as those on the stages power meter.

    • Lee

      I have commuted in some serious nasty weather and have had no issues. A few rides I was worried about how much water there was. Like a previous post, I opened it up after the ride and it was totally dry.

  53. Russ

    I’m confused about the crank arm length. I don’t see how to specify that on CT or the 4iii page. I see in one comment that yours is 172.5. Is that size fixed?

  54. Craig J Hoskin

    4iiii just announced deilvery in July for the dual sides
    link to 4iiii.com

    and analysis in 3d….
    link to 4iiii.com

    • Lee

      So from what I’m reading is the new 2.0 left only pod is $399 (sucks that I have the old one since January). The Dual side is $749 and only available for Dura-Ace at this point? I’m sure hoping they will offer an upgrade path for the original left side owners, but it concerns me that they now offer a new pod which makes me think the old pod will not be compatible up to dual side.

    • John

      Yeah, not really sure about the need for a Dura-Ace crankset exclusive, maybe that’s just a way to manage initial demand?

      I’ll be first in line with an Ultegra crankset when they get to them.

    • Craig Hoskin

      From Rays latest update:
      “Note that 4iiii is doing right by Gen1 customers wanting to upgrade to dual. In July you’ll send in your existing left crank arm (with the right crank too) and they’ll upgrade your old pod to Gen2, no extra cost.”

      link to dcrainmaker.com

    • John

      That some fantastic customer service!

  55. Elvin

    Hi Ray, your Mean Max Curve seems reveal that balance scale factor only needs to be adjusted in specific situation such as sprint. But as it is a constant factor, it will underestimate the rest input if you try to reduce the sprint output. I guess only double leg measurement can help here. I wonder how Stage dealing with this problem, or the pros doesn’t care about it?

    • Unfortunately for most people, left/right balance is not a constant factor. It usually varies based on wattage output, fatigue, even indoor vs outdoor.

      Stages, like 4iiii, simply doubles the left power. As for Pros, no, Team Sky didn’t care because they were getting paid not to care. Yet, these days they run a dual Stages system (left/right) that’s not available to the public (just like Team Etixx Quickstep does with 4iiii).

      Said differently: The pros have realized that capturing both left & right power is truly important to accurate measurements. ;)

  56. Michael

    I wonder if anyone was successful in using the Polar V650 with the 4iiii Precision.

    I got them paired/repairend on the 2nd attempt, but didn’t get any data displayed by the V650. Instead the V650 frequently notifies about a not responding left side power meter…

    • Hello Michael,

      Polar’s V650 is only compatible with some Bluetooth power meters. It would be best to check with them regarding compatibility.

      4iiii Support

    • Davesee

      Michael–any luck with the V650? 4iiii’s website is saying it’s not compatible so curious what your experience has been since having this issue.

    • Michael

      The V650 definitely doesn’t work with the 4iiii PRECISION. I contacted the Polar headquarter in Finland and they confirmed that it isn’t compatible. Further on they weren’t able to give a date when the firmware will support it.
      I changed to the M450, which is compatible. And that the most strange thing about it. why isn’t Polar able to update the V650 when they already have the code available for the M450?

    • Davesee

      Very strange indeed since V650 is supposed to pro level, right?. Has it worked well with M450? I know DCR has mentioned a couple of times broadcasting power via bluetooth can be an issue.

    • Michael Swann

      The reason would be because the V650 is built on a different software base to the M450. The V650 is based on Android whereas the M450, M400 and V800 are all based on a proprietary code base and changes introduced to one are able to be introduced to the others fairly quickly (at least in Polar speeds) compared to changes for the V650 because of the similarities between them.

      The V650 is a strange beast. Polar tout it as their top of the line cycling computer, but it’s really a standalone product and not something that could be used seriously. There are compatibility issues with various power meters (even though the Bluetooth Smart protocols are supposed to be open).

      I still follow what Polar do and I’m guessing it still can’t do any sort of workouts. Something I think you would want in a top level device. Not that I found the audio volumes to be that loud, so you would probably spend more time looking at the unit than you should to make sure you were in the right zone. By comparison I never had any problems hearing the beeper on the M450.

      I had both for a while. I liked the M450 better from a usability point and because of its smaller size. I sold them both and I like my Garmin Edge 520 a lot more.

    • Davesee

      Thanks Michael Swann!!! That explains so much. Was hoping to get along with V650 for a while but sounds like may have to change computers when I purchase a power meter. When I get closer to purchase I’ll post to M450 and V650 reviews to get a feel how power connected via bluetooth is working or if I’ll need to switch to Garmin or Wahoo (ie something with ANT). Hope you 4iiii arrives soon!

    • Michael Swann

      Thanks. It was relatively quick for my parcel to get from America to Australia (5 days via Dubai!), but another 5 days to get from Melbourne to Adelaide. I got the notification that it’s waiting for me to pick up on my way home tonight. I should get it installed over the weekend.

  57. hong

    The Buy Now: Clever Training link is not working. Goes to link to clevertraining.com which returns 404 Not Found page.

    Thanks for all your fantastic reviews!

  58. SMB

    10% off for DCR readers?

  59. Joanne

    Great review! Noticed these are available for Pre-order on Probikekit, Do you know if they are shippable to US?

  60. Amy

    I recently purchased the 4iiii Precision power meter and felt I’d been consistently having a lower wattage reading than I felt I was putting out. After a few weeks of rides and feeling like my effort was too high for the wattage output I thought it was time to test it. And after testing it against two other power meters (one being a indoor testing facility that I am is sure accurate) my meter reads almost perfectly 15-20 watts too low across the board, low to high effort. And that is killing me in higher efforts. I warm up for a bit and zero calibrate every single ride. So I took note of my calibration numbers and the first number is always over 11,000, around 11,400-11,700 range which appears to be out of normal range. The second number just squeaks in under 21,000, usually 20,700-20,800. My head unit is an Edge 500. I am at a loss, I have emailed the support about 4 days ago. I was hoping someone on here could help me out?? Am I doing something wrong?? Should I try something? I upgraded to the latest firmware thru the app without any issues. Even used the app to make sure wattage reading on my phone was the same as my Garmin.

    • Pearl at 4iiii

      Hello Amy

      The range for the numbers is:
      Number 1: 4000-15000
      Number 2: 15000-25000

      Your numbers are well within those ranges. I am guessing you were looking at an older version of our user guide which had a tighter range.

    • Maarten

      After using the PM without any problems for a little under a year, all of a sudden I’m now experiencing the same problems as Amy. My wattage readings have skyrocketed to numbers in excess of 8000w. When calibrating, the first number no longer reads around 8000 as it used to do, but instead I see numbers in a range of -28000 to 28000. The second number is unchanged around 20740. Have the latest firmware installed, tried factory reset, change battery, etc. Anyone have any other suggestions? Wish I could reinstall the previous firmware, no problems with the unit back then!

    • Maarten – Have you tried reaching out to support?

    • Maarten

      Ray, thanks for the quick response. I have sent 4iiii an email Friday evening UK time. They probably haven’t had a chance to look at my email yet. I was just hoping that someone with similar issues had found a solution. I can’t seem to find a user group or forum anywhere that discusses some of the Precision related issues, aside from this post! I’m sure they’ll contact me in the coming days, I’ve always experienced good customer service from them.

      On a side note, what does slightly worry me is that my cranks (Cannondale SISL2) is no longer listed as a compatible crank.

    • Amy

      A follow up comment about some issues. I used a compu-trainer and Elite stationary trainer to dial in a factor to try and make the meter more accurate. That seemed to work out good, it’s not accurate on the lower end, (up to 60 watts) but once I get into the higher end of things it’s more accurate now. So it’s been great since then. So I did the latest update (1.5.0). I’d been hesitant to install just because things had been working so well, I didn’t want to ginks it. So I did the update and it said to remove the battery after the update. So I did. And then nothing. App wouldn’t connect, Garmin wouldn’t connect, it was like it was dead. Nothing, no bluetooth pairing, in fact, there was nothing to pair to. So after two days of trying like 50+ times, new batteries, I pressed really hard on the cap and then bam, it connected. But when I took my finger off, dead again. So I knew something wasn’t making a connection. So I removed the battery and cleaned the contacts with a q-tip. Nothing. So I removed it again and (I wish I had a pic) on the inside flat face are the larger contacts and they were fine, clean and looked great. But on the inside rim is a smaller, single contact. I think it got/gets pushed in too much and stopped making good contact with the cap/battery. So I used a toothpick to lightly pry it away from the outer rim in hopes of making good contact. And voila, it worked. Paired with phone, app connected and Garmin connected. It calibrated with the Garmin too. I thought I would post here in case someone else has the same problem. Removing the cap/battery could push this tab down too much and cause a loss of connection. If your unit is dead in the water and you recently removed the cap or replaced the battery, just give this a try.

    • Pearl

      Hi Maarten
      a complete response has been emailed to you from support@4iiii.com.

    • Maarten

      Just to follow up on this, 4iiii has taken sublime care of my issue. I’ve sent my PM over from London to Canada on 21 June and today received my crank arm with a new PM installed. Compliments to Pearl and the 4iiii team for dealing with the problem so quickly.

    • Nawar

      Hi when I calibrated my powermeter I get those

      Number 10669 – 20754

      Is there any errors with my powermeter ? Because I think it’s read lower watts than what I proudce

  61. Torsten

    Hi Ray,
    What is your experience with precision 2.0.
    I did my first 3 rides after receiving it 2 weeks ago and was quite disappointed.
    The watt figures even with 10s smoothing applied are jumping around by up to +- 50 Watt every couple seconds without changes in conditions or intentional changes in applied power. And it is not correlating with the push/pull cycle.
    4iiii informed me that I am one of the first customers who receives the new version. My assumption is that this upgrade is not really ready for production yet and I may have been selected as an alpha or beta tester. At least support from 4iiii so far was great an I will probably receive a feed back soon after I have supplied my .fit file.

    • I’d work with 4iiii support, as something definitely sounds amiss, so getting them the .FIT file will help them troubleshoot and see if it’s somehow just a bad unit, or something got damaged/etc…

    • Torsten

      yes of course 4iiii has the .fit file and they are working on it for some days now. I was just curious if there is anybody out there who has a functioning version 2.0 already.

    • Frank

      Same issue here, I got my version 2 this week (On a Dura-Ace 9000) crank and the battery cap was broken… To their credit, I emailed them within a hour of getting it and they Fedex me a replacement cap. Now the real problem. I have been riding with it on a Tacx Vortex trainer for a couple days now and it is a complete mess. Though the trainer says 150-200 watts in general, Apparently I am pushing 375-550 watts with the 4iiii, going between 18-20mph, no resistance (As reported by their iPhone app and my Garmin 520). And the readings jump around second to second as if I was riding on cobble stones or something. I have tried for a couple days to contact customer support, since the cap issue, but they will not respond to my emails. Took the money and ran…..Horrible….

      I will let you know if I ever hear back, but for now looks like I have an expensive paperweight on my hands. I even wrote to the sales unit, but they would not respond either. DC really needs to consider taking them off his list until their Customer Support is more reliable, especially if their PowerMeters don’t work consistently.

    • Hmm, it’s not normal for them to not respond (usually they respond quite quickly, as other folks have noted here). Any chance their responses are going into your Junk/Clutter/Spam folders somehow?

      (Also note that just below your post they are replying here to folks as well)

    • Pearl @ 4iiii

      Hi Frank

      Pearl from 4iiii here.

      I am surprised that you haven’t been able to connect with us since we have you as an authorized email in our help desk. I searched our help desk and other than you order emails and battery cap issues we truly haven’t received anything from you. Please try contacting us again at either support@4iiii.com; cranks@4iiii.com or give us a call at 1.800.218.3095. and we’ll get your unit fixed.

    • Torte

      I love your short and in depth reviews. It is so helpful to get an objective overview and insights about, what is on the market.
      The same was true for the precision 1.x review. However, after 4iiii moved to version 2.0 I think the review could be misleading because the reviewed product is not what you get when you order. And looking into the feed back here concerning v.2.0 it is overwhelmingly poor. There is no indication that 4iiii has the mentioned issues solved what renders at least a significant amount of those products useless. It would be helpful for readers may be to mention at the begin of the review that the reviewed product is not anymore available (may be on special request only) and that the current product has not been reviewed yet or people should follow the comment at the end to find out more about current complaints.
      I sent my fit file to 4iiii May 4th with quick response from support what was great. However, until today it does not seem that there is a solution.

    • Frank

      As a follow up, Yesterday I did receive a follow up from both Pearl and another customer service rep from 4iiii. Looks like they were having some technical issues which prevented them from receiving my emails for a couple days. (They do need to look at contingency or COB plans in the event email is not working again especially since this is the only support lifeline provided to consumers (RE: No general Chat or Phone communication).

      Looks like they are going to release new Firmware next week 5/23-27. Once installed I will post the results. They also asked for me to wait till the firmware was released and to contact them and they would help me immedattiatley if it did not help resolve me issue (Nice touch!!) If all goes well, I will be requesting an upgrade to the right side as I have had previous success in writing to 4iiii for feedback, their shipping agreement and timeline was spot on, and their initial warranty follow up was over the top fantastic. Figures crossed that all works out.

    • Aaron

      Thanks for the update, Frank!

      I had un-paired the Precision because the power data was so inaccurate and unreliable, so I’m super-excited to hear about the firmware release next week. Fingers crossed this solves the problem.

    • Frank

      As a follow up. Looks like the firmware is a little delayed, however, in the meantime, I did some more reading of the boards, and some feedback from 4iiii, I was able to correct my issues and ride very well.
      1) I reset the factory settings
      2) I recalibrated with no motion, no clip in, the crank facing straight down

      With this and the use of the averaging reading I was able to closely sync with my Tacx Vortex Trainer and also get a great ride in with reliable readings. Looking forward to some great rides going forward and also the right sided power meter install.


    • Aaron

      I tried this on my Precision v2 and it seemed to work… Until the water stop about 25% into the ride, when presumably the PM went to sleep due to inactivity. When I started back up again, the erratic readings were back… Eventually the Precision gave up completely and just returned 0W even though I was pedaling (cadence readings seemed spot on). I tried steps 1 and 2 again, but it didn’t work this time (did I mention that it was raining on me while I was sitting there fumbling with my phone to do factory reset?). Ultimately, I unpaired the Precision PM and went on with the ride without power readings.

      Using a Garmin Edge 520, so paired ANT+.

      Pretty disappointed with the PM. Debating a return…

    • Pearl

      Hi Aaron
      Have you contacted 4iiii customer support with any of your issues? We would be happy to help. support@4iiii.com. Just looking at your history here, I would say that the new firmware will address your problems. Release date is June 7.

    • Aaron

      Hi Pearl,
      Yes, I sent a note to 4iiii support late last week and got a response this morning from Lee. He’s looking into it. This was before I knew that the sleep/wake cycle mid-ride may confuse/break my Precision PM. Is this a known problem?

      I have my fingers crossed that the firmware update will address the issues I’ve seen, so I’ll see what I get after 6/7.

      Thanks for the response!

    • Carl J

      Nearly 7 years later, and I’m having the same issue as you with a brand PM from them. Actually, make that 2 PMs from them.

      I purchased one in Oct 2021, and it was reading 30-40W higher than my previous 2 Stages Gen 2s. Also, I showed them from a .FIT file that the power was jumping around a lot. They quickly got me to send it back.

      Now I just received a replacement yesterday from them and tested it out again today. Holding a steady cadence, the PM readings would drop to 170W and spike at around 240W (but usually 180-210W).

      Was really excited to try 4iiiis, but now I think I’m going to go back with Stages.

  62. Bici

    Hi Ray,

    a friend of mine will get one of these in a couple of days and I have to figure out a software-workflow him. I want to try out goldencheetah 3.1 and 3.3 and need a .fit sample file to test.
    It would be really great if someone can provide a sample .fit file to test or give a link to file.

    Thank you for your “massive” tests.

  63. Michael

    Was anyone successful in zeroing the PRECISION with the 4iiii Android app?

    Despite Pearls instant support I’m not able to zero it with my smart phone. PRECISION firmware is 0.4.0, SW version of the app is 1.5.0. Both are as far as I know the latest ones.

    Maybe there’s an incompatibility between my smart phone or the Android version and the app…

    • Pearl @ 4iiii

      Hi Michael

      I referenced your PRECISION serial number and it looks like we also had some more issues with your unit. Pop me another email to support@4iiii.com so we can start the RMA process.

    • Rob

      So does anyone have a properly working V2 4iiii here?
      I’d love to buy one, but fearful having read the comments.

    • Rob

      Also I notice firmware is at 0.4.1, this being the case is the product still in beta, as I have always thought a designation of 1.x.x would be a full production firmware?

    • Sometimes, but not always.

    • Pearl at 4iiii

      Hi Rob
      The PRECISION v 2 (as well as Gen 1) both are functioning. The problem that you reference was simply an allocation of the unit serial number to the database grouping for the version released. This has now been corrected.

    • Pearl at 4iiii

      Rob – our nomenclature may differ from yours. Our Beta firmware versions are fully tested before public release. As a head’s up, new firmware version 1.x.x will be released shortly.

    • Michael

      This is getting more and more anoying.

      I received my unit end of April and I never get it running. It’s impossible to zero it by the 4iiii Android app. Firmware of my unit is 0.4.0 and Pearl adviced me to update it to 0.4.1. Trying the update I always get the message that it is up to date. Later Pearl confirmed that 0.4.0 is the latest. Here I can read that there is a FW 0.4.1 available.

      Now I’m asked to return it to 4iiii. I mailed Pearl twice how to proceed and didn’t get an answer. Wasn’t the unit properly checked before it left 4iiii. I’m located in Germany and shipping it back and forth is always an effort and takes time. Meanwhile I can’t ride the bike.

      I’m completely disappointed about the PRECISION. For now it’s just a piece of useless crap to me.

    • Pearl

      You were asked to return your crank for repair as your unit could not be fixed remotely.
      Version 0.4.0 is the firmware for Gen 1 PRECISION units.
      Verision 0.4.1 is the firmware for Gen 2 units. We require different versions as Gen 2 has an additional strain gauge.

      Presumably repair of your unit will convert it from “a piece of useless c****” to a tool you can use for your training. Repair units are always priority in our queue so turn around is very quick. We do try to accommodate customers with racing schedules and have a loaner crank program.

      We are trying to catch up to tickets that were misdirected over the past two weeks. I see your ticket arrived on Monday (a holiday here in Canada).


    Hi, considering buying the new G2 4iii power meter here in the UK. Have all the issues mention above now been solved? Also, is it possible to zero (calibrate) the power meter while riding? I say this, as I often ride early in the morning when the temp is very low, but finish the ride when temps are very high. Without active temp compensation I fear the power numbers will not be accurate. Thanks

    • Torsten

      Hi Mark,

      My iussues are not solved and you should not rely an DCS review when it comes to accuracy if the product.
      1) Issue with DCR’s product sourcing
      As DCR explained the review is not based on a random shippment. This is fine if the producer has production process under control and you can trust that the product you receive is comparable with the product hand selected and may be massaged for DCR.
      2) No effectiv pre shippment product quality control
      With what I am reading and what I have experienced there is no in production quality control. The product quality control is left to the customer unless you are DCR. And this is especially bad if it is how it seems that 4iiii has production issues.
      3) Cost of importing to Europe
      Since you are from the UK you have to consider that it is more troublesome to send the unit back one ore more times. I imported the device to Germany and paid overall for VAD, Custom and fedex handling 98,- EUR. A small part of it is VAD and Custom for my own used crank arm due to wrong shipment declaration by 4iiii. So, I would be positively surprised if there is no new fee I need to pay to fedex for the product return.
      4) Issue still not solved
      The latest is that I have been advice to wait for the new firmware after 4.01. I tried to upload it today but in contrast to what has been promised there was no update available.
      An the remedy from Frank is not working for me. I have done all this things from the begin.
      5) Can you Zero between rides?
      Don’t know what the impact to seamless recording is. I did not try it because anyway readings are not accurate in my case.


      Thanks for your reply Torsten. In the UK you can now buy the crank with the power meter already installed, so no need to send off your crank to 4iii in Canada. It cost a little bit more, but it means no hassle with shipping your own crank. Hopefully these pre installed power meters have been checked and passed some sort of quality control.

      I really hope you get your 4iii power meter problems sorted out. I think i’ll wait until people start saying the 4iiii G2 is working before I purchase one.

    • Michael

      I agree to Torsten. In particular concerning point 2).

      I received my unit end of March and since then I’m struggeling to get in running. It’s impossible to zero it via BTE. Can’t say about ANT+ because of no available ANT+ device.

      So theres definitly no proper quality control in place. Paired with an unstable manufactuirng process oversea shipments become jeopardizing.

      No I’m in the process of returning it to 4iiii. Located in Germany this is no fun at all. It’s very excitng to see if I’ve to pay customs and VAT again receiving the unit back from service.

      So I recommend everyone not located in Canada or North America to wait until all issues are fixed, manufacturing process is stable and quality controll took place.

    • Hmm, I think there’s some confusion.

      1) Product Sourcing: I actually often source products from random retailers. In fact, eventually all products I use are just from retail. It appears you even missed the very first section (3rd paragraph) where I talk about how many attempts it took initially to get a good unit. And that process. A process which seems addressed based on lack of complaints from others since then.

      2) Quality Control: If I understand things correctly, there is now a total of 2, perhaps 3 people who had issues with a Gen 2 unit (including you). The other person, Frank (above) it sounds like 4iiii is working with him to sort out his issue. Given 4iiii is shipping boatloads of these per day, it stands to reason that this is simply a case of a lemon along the way for some reason. It happens to all companies, big and small. And, as is usually the case, people find the first thing that Google returns for a given product (here usually) and write about it. Happy people don’t tend to post.

      3) Cost of importing to Europe: Actually, you’d only pay customs on the first one, as you bought a product out of the country. But then again, you paid less than a power meter would cost in Europe (which you know). Folks haven’t said there’s been any issues with repairs costing anything from a VAT standpoint.

      4) Have you talked with 4iiii since trying and it not working?

    • Michael-

      You don’t have a Gen2 unit, since if you received in March, that was before they announced the units in mid-April.


    • Pearl

      Hi Michael
      We appreciate your sharing your experience.
      To clarify, the duty and taxes for RMA repaired units are covered by 4iiii Innovations. In the event that you are billed in error, notify us and we will have the charges reversed.

    • Pearl

      Hello Torsten
      We’re sorry that the delivery date for the new firmware was not met. The development team decided that we would release the new app first and then the firmware. You can expect the new app in the store on Wednesday June 1.
      To clarify – the version last released for Gen 2 models was 0.4.1; for Gen 1 models was 0.4.0.

      The new firmware will be 1.0.0.

    • Michael

      Hi Ray,

      of course I know that my unit is Gen1. But nevertheless it’s hard to understand how a device that can’t be zeroed left the plant. I would expect a 100% EOL covering every function. If this is in place no faulty device is going out.

    • Torsten

      Ray, I think we should allow for critical replies to specific questions even when the experience is a little less satisfying then your review may suggest.
      From what you wrote at the top of your review it is very hard to recognize what you claim now that all testing has been done on an anonymously purchased product. Didn’t you write that the product needed to be sent back twice to you and you had some conversation concerning your right/left leg anomaly? Your great accuracy results have then been done with a 2 times fixed unit (Gen 1 by the way) which has been shipped to you. Why do you think that 4i did not know that the fixed unit was for your?
      And please help me. What makes you so confident that there is no issue with getting consistent quality from Gen2 manufacturing? 2 people confirmed that they have a bad product and nobody so far replied to my question if anybody has gotten a functioning Gen2 version which matches your great test results. In addition I am talking about Gen2. And as you know, your accuracy testing documented Dec-2015 has been done with Gen1 way bevor Gen2 has been released in Apr-2016. In the middle of the review you now mention that you are on Gen2 without telling if any of the graphs have been updated. May be you could clarify that a bit.
      And what further makes be suspicious about a general quality issue is the fact that 4iiii says that they moved to Gen2 what “moves traditional power monitoring a quantum step ahead to improve accuracy and …”. But why does anybody need improved accuracy if it is as brilliant as your charts are showing (< 1% deviation from competitors power meter).

      To say it again, I love your reviews. And I can not imagine how it could be any better. It just strikes me why you are so much insisting that everything is perfect with Gen1 and Gen2 without providing any reasonable argument. What keeps me somehow relaxed is that I can rely on an exceptional support from 4iiii, but still would now be a little patient to order from Europe until there is some evidence that most Gen2 are working accurate.

    • RE: 1 – Sending back product: It had nothing to do with quality control. It took 6 months of them realizing/fixing their algorithms/design had a flaw in it, that didn’t account for specific pedaling styles (apparently mine). It wasn’t a fixed unit, it was brand new (in many ways) with new algorithms. You’ll remember during that time I placed banners/warnings at the top of all my pages basically saying it wasn’t working for me, but was working for others.

      RE: Gen2 units: I’m not saying you aren’t having a problem, but rather I’m responding to someone above saying that all Gen2 units are somehow broken. Or, to the fact that some people are trying mix in a random Gen1 unit in implying it’s Gen2. That’s all. I’m simply pointing out that when anyone says that, it’s usually BS. If every unit that was leaving 4iiii was broken, then this post would have been immediately swamped with comments of people having issues. It’s not.

      The problem here is that 4iiii and folks here are calling these units ‘Gen2’, when in reality, they also called the ones back in October Gen2. Thus, confusing the crap out of things. These probably should have been called Gen3, which would have fit in nicely with the ‘3D’ marketing stuff they’re doing.

    • Karl

      Servus Michael,

      had the same issue with my gen1 PM – Problem was I had removed the Batterie and inserted the same used one again, which leads to the issue not beeing able to Zero anymore.

      Pearl’s answer solved it for me:
      This appears to be caused by a low voltage battery problem.

      Follow these instructions to perform a clean and perfect zero offset using 4iiii app:
      1 – Exit 4iiii application and kill the app
      2 – Restart Bluetooth by turning off and on Bluetooth radio
      3 – Put a fresh battery on the power meter
      4 – Run 4iiii application and after connecting to the power meter, go to “PRECISION configuration” menu
      5 – Click on “PRECISION Info” button
      6 – Make sure the Battery Level is 100% and then click on “Advanced Config” (iOS) or choose “Enabled Advanced” from the app menu (top right of screen)
      7 – Click on “Zero” button and wait for the response. Don’t forget to put the crank in vertical orientation ;)

      You can perform Zero any time between 100% and 15%.
      The problem is:
      If you put a new battery, it shows 100% and counts down the percentage but if you put used or old one, since the pod doesn’t have any history of that battery, it shows 50% by default (and counts down).
      It means, you can trust battery percentage only when you put a new battery and you never remove it until getting low battery message. The battery usage tracking system works only on new batteries.

    • Michael

      Hello Karl,

      as I received my PRECISION I set it in operation with one of the batteries provided by 4iiii. And from the start with the new battery in place (charge shown was 100%) it refused being zeroed.
      So I replaced it by the 2nd battery provided by 4iiii. same result.

      But one other point: If zeroing is possible between 100% and 15% battery charge only what does this mean if it is neccessary to zero prior every ride? Simply that you have to live with less accuracy for the remaing 15% battery charge or to replace it as it gets below 15%.

    • Eric

      I am very happy with my new Precision V2 and with the coustomer support.

      2) My Precision V2 works fine – even during rain
      3) Cost of importing to Switzerland: 45€/48CHF
      4) pairing with my Android phone (Motorla Moto G2) is difficult. It works better with my Ipad3. I have the same bluetooth difficulties with other Bluetooth gadget f.e. Wahoo TICKR X
      5) Yes I can by Garmin or by the app.

    • Richard R

      Hi Torsten, I had to send back my 1st Gen power meter as it wouldn’t connect anymore, they sent me a 2nd Gen power meter as a replacement and since then I haven’t had a single problem with it.

      I am obviously just 1 person, but for me it seems all good at the moment

    • Javier

      Only 45€? I’m considering to buy it, but usually in Spain, we have to pay 21% as VAT (including shipping costs…) plus mail “handling” (about 20-30€ more). I’m guessing it would cost me about 100€ or more. I don’t know how it works in Switzerland… but one guy from Austria (Karl I think) stated above more or less the same taxes I have told you… I really wish to have your luck in this case.

    • Eric

      The same in Switzerland, but the VAT in Switzerland is about 8%. :-))

  65. TMR1980

    Hi. Noticed the stages PM only needs to be zero offset every week but the 4iiii Precision needs to be zero offset every ride. Ideally don’t want to have to do this every ride. what is the reason for the difference, is it just down to manufacturer opnion / advice or is stages more capable of not being offset as frequently?

    • Actually, Stages wording it kinda funny. Basically it’s marketing spin. As they admit in their own support article that if you care about your data being accurate/trustable (such as for a race or fitness test), you could zero offset: link to support.stagescycling.com

    • Torsten

      Thanks Ray,
      I am curious how the charts would look like in more detail if the unit works as it should..
      Would you mind to make one of the .fit files available you used as source for your review? I am aware that the tested version is different from mine.

    • TMR1980

      So I get that best practice is to zero reset a PM every ride….if I didn’t zero reset the 4iii every ride e.g. once per week are the results still likely to be relatively accurate? Or do you think the Stages would be more accurate due to the automatic temperature compensation?

    • Hi Torsten-

      All of my original data from the review is within the zip file at the end of the ‘Power Meter Accuracy Results’ section. It’s the last line: link to dcrainmaker.com

      While in newer reviews (like, last week new), I also link to the individual charts in my analysis tool – I didn’t have that option last fall. But, I just went and picked one of the charts from above (the Nov 8th one), and set it as public. So it’ll save you time from having to find a way to compare the original files in another tool. Here’s a link to that for that plot: link to analyze.dcrainmaker.com


      I would suspect so, but I didn’t test for that. I typically zero all power meters at the beginning of all rides, and then often about 10-20mins into a ride since most temp compensation systems take about that long to take effect when going from indoors to outdoors.



    So does 4iiii have active temp compensation or during a long La Marmotte type event, were temperature can vary from one extreme to another, would have to zero the offset throughout the ride? This is important as I really just want to zero the 4iiii at the beginning of the ride and leave it.

    • Hello Mark,

      PRECISION was designed to maintain a high level of accuracy across a range of temperatures. Should we find that additional compensation mechanisms are necessary, we will address that need through a future firmware revision. We continue to recommend that riders re-zero PRECISION before every ride.

  67. Brantel

    Any options for us out here with the RS500 compact crank to use one of these by swapping out the left crank arm with a model that is flat on the inside? If so, which one will fit the RS500 crank and be close to the same weight?

    • Pearl

      All of the Shimano crank arms that are compatible with PRECISION (105, Ultegra and Dura-Ace) will be compatible with your crankset, since they all use the same Hollowtech II interface between the left and right sides. There will be no inaccuracy induced by running such a combination. The only thing to be careful of, is to make sure that the new crank arm is the same length as that on your right side.

      In a 172.5 length the left crank arm models weigh (in grams) as follows:

      105-5800: 198
      Ultegra 6800: 202
      Dura-Ace 9000: 176

      I don’t have the weight of the RS500 left crank arm but due to its construction it will be heavier than any of these 3 models. However you should not experience any significant imbalance if you were to use one of these with the 9gm PRECISION installed.

    • Stephen

      Pearl said: <<I don’t have the weight of the RS500 left crank arm but due to its construction it will be heavier than any of these 3 models. However you should not experience any significant imbalance if you were to use one of these with the 9gm PRECISION installed.<<

      I had an RS500 crank on my bike. Found a lightly-used Ultegra 6800 crankset with the intention of sending the left arm to 4iiii for installation, so I put the RS500 left crank arm on the Ultegra–which is the opposite "switch". It works fine and I'm not sensitive enough to notice any difference whatsoever. The Ultegra crank arm will go back on the bike as soon as I'm recovered from a broken arm. Unfortunately with no 4iiii power meter–I gave up after being promised someone from 4iiii would contact me to discuss my issues with the "upgrade" policy for purchasers of single-sided units. All that seems to have been resolved, but too late for me. Overall, I think Pearl has performed very well and has been as helpful as she could have been. Not her fault whoever was supposed to get in touch with me didn't.

      Bottom line: I'm really tired of the starts and stops, promises, changed promises, failures, upgrades, improvements and these are not just related to 4iiii, but the industry in general. It's just flaky beyond belief taken as a whole. I'm thinking of just getting started with a Powerpod as a "good enough" device and wait for the day, which I'm certain is not far off, when power meters cost <$100.00, come standard on premium bikes and "just work."


    • John

      What makes you think the Powerpod is without problems?

  68. Stages or 4iiii?

    • TMR1980

      I had same dilemma and bought 4iiii largely because of lower price. It seems v consistent and as I’m new to power cant comment on accuracy. Its worked exactly as it should do 2 days in. 4iii is cheaper, maybe not been on market as long as Stages and gives you ability to upgrade to double sided. I know from experience that the 4iiii customer service is top notch. All that said Stages get good reviews and are a proven product.

  69. Torsten

    Hurray, yesterday I had another check to see if the promised new firmware for the Precisioin Gen2 is available, which may solve my issues. And yes, there was a new version 1.50 available. So I updated and did a short test run. And yes, much to my joy, the precision was working as expected more or less. The up and down power spikes disappeared and just of a sudden the 9g useless piece of plastic got a purpose.
    I am happy that I was waiting for the 4iiii guys to come up with a release that finally turns the Precision Gen2 into a power meter.

  70. Jacky Wong

    I just ordered the ride ready one and expected to receive it on July from CT. Hope there is no delay.

  71. Chris Wiswell

    Hey does anybody know if this has the same issues as Stages with it dropping out on GPS Watches?

  72. Brian Mosley

    As a father of 3, I have limited buying power, your reviews have helped me tremendously!! Thanks for the awesome 4iiii review and other reviews as well. Saving up for one now. Love your site!

  73. Andrew

    I recently received a Precision and have a query for Ray, Pearl and/or other 4iiii staff please?

    Do I understand correctly that the precision does not have an auto-zero type of function – eg similar to pedaling backwards on some other power meters? This was kind of asked above but not answered?

    Also, I have a Quarq pm (Red 22 model), and when paired to a Garmin 520, upon waking up the quarq the 520 detects it and the ‘calibration’ message pops up right away to allow for auto-zeroing. This, however, doesn’t happen with the Precision upon wake up, so you have to flick through the menus to get to the cal/zero page. Does anyone know why this feature of the 520 doesn’t work with the Precision? Am I doing something wrong? Is this linked to the (assumed?) lack of an auto-zero feature – eg do 4iiii insist on riding for several minutes before zeroing?

    Final note, the Precision has worked flawlessly within the bounds which I have used it. Pairing and zeroing on the 520 worked right away, firmware upgrade has been fine and no dropouts at all. Haven’t bothered connecting to ride or zero vie Bluetooth so can’t comment on that. Also can’t compare numbers to the quarq but have no good reason to believe the number aren’t tight.

    Thanks in advance!

  74. Jacky Wong

    The official announcement said the ride-ready PM will be deliver on early July. Did anyone received it?

  75. Kerem

    I placed my order ( ride ready )6 days ago and now its on the way by fedex

  76. Jacky Wong

    I bought it through CT, hope it won’t take too long.

    • Pearl

      Ride Ready orders placed directly with 4iiii Innovations began shipping June 30. Please contact your dealer for a delivery date for your order.

    • Jacky Wong

      Thanks, Pearl. I checked my online record in CT website. No luck at this moment. Will e-mail them today.

    • Jacky Wong

      checked with CleverTraining, the ride-ready PM is not arrived yet and they don’t have any shipping schedule from 4iiii. It is 12th Jul now, I am worry that I won’t able to receive it within July 2016.

    • Chris

      I have a Gen 1 precision. The other day mid ride I lost power but still had cadence. Changed battery, restored factory calibration, zero calibration. Nothing has seemed to work. Anyone else have this problem?

    • Dr_LHA

      So what’s going on with the Clever Training orders? I emailed them today and they told me no news yet on a ship date. Given that they already charged my credit card for this thing 2 months ago (which I have to admit I was pretty peeved at, most companies won’t charge until an item ships), it’d be nice to know a real shipping date.

    • Jacky

      I also want to know, it is the first time that I buy from clevertraining. Up to now, I don’t know when it will be delivered to me and there is no update from CT.

    • I reached out to CT, who has been trying to get information from 4iiii. It sounds like there was some substantial turnover at 4iiii’s in the order processing department.

      Either way, they’re escalating and hope to have an answer shortly.

    • Jacky Wong

      Highly appreciate your help. Usually it shouldn’t be problem from CT side. I was wondering 4iiii fulfill all direct order before deliver to CT. Now the root cause is found because of your help. Thanks again. :)

    • Dr_LHA

      Thanks Ray.

      BTW Jacky, I assume that the “substantial turnover” being referred to here is staff turnover at 4iiii.

    • Yes, correct, at 4iiii’s in the position that liasoned with retailers.

    • Dr_LHA

      Thanks I presume to Ray’s intervention, I got my answer. Delivery expected late August. *Sigh*.

    • lkr

      Contact 4iiii [info@4iiii.com]. I’ve found them very responsive in walking through the problem.

  77. John

    I have a Ride Ready Ultegra on order from CT with the same “mid-July” ship date as everyone else, but the 820 I preordered on Wednesday shipped this afternoon, so they are obviously shipping what they have in stock. Maybe someone from 4iiii can chime in on availability?

    • Pearl

      The world-wide adoption of PRECISION is strong and we are working hard and fast to get PRECISION on your ride.

      1. Clever Training has received Ride Ready inventory and more is being shipped this week

      2. Some models can be more quickly filled via our Factory Install Program.

      3. Yes, we are growing fast and looking for talent. Looking forward to hearing from passionate riders.

    • Jacky Wong

      Thanks, Pearl.
      Hope I can receive my PM soon.

  78. Jacky Wong

    I would like to share a good news, my 4iiii ride ready PM is on the way to my home. Expected to receive it on Monday evening.

    • Deji Odetoyinbo

      Jacky Wong, did you receive yours? How has it been? I’m about to place my order for a Precision Pro. Trying to get a sense of whether the production / delivery difficulties have been sorted out.

    • Jacky Wong

      Yes, I received it on 25 Jul from CleverTraining. It works and I am sure you will love it too.
      But don’t forget to install it with required torque. Otherwise, the measurement maybe wrong.

    • Dr_LHA

      Still waiting for mine, ordered back in May.

      So no, the production / delivery difficulties haven’t been “sorted out” IMHO.

    • Dr_LHA

      In case anyone cares, I finally got my 4iiii PM in the mail yesterday.

  79. Jacky Wong

    Need help from other owner of 4iiii PM.
    I found that I got 3-4 difference reading within 1-2 seconds.
    From less than 100w to 180w.
    Is it normal? Please share your valuable comment with me.

  80. Nawar

    Jacky I think it’s ok it happens to me but you should choose avg power for 3 or 10 sec from your garmin better than current power .
    I hope my reply is clear my English not that good

  81. David Zak

    Hi Jacky, I’m interesting if the 105 left crank will work with Sora chainrings, can change only cranks on my Sora? Is it possible, anyone tried this?

  82. Marklemcd

    I bought the precision with the factory install option today (8/26), I wonder how long the total turnaround will be? Will there be a long lag before I get my shipping package?

    • Pearl

      Hi Mark
      We are ready to receive you crank arm for installation. Your shipping logistics have been sent to you from 4iiii.com.

  83. Adrian Cartlidge

    Warning – if you are from the UK do not buy this product direct from 4iii in Canada or USA. Although its tons cheaper to send off your own crank arm and have them fit it you will get stung with a huge duty and tax import charge like i did. I payed £340 for the crank arm installation onto my ultegra left crank arm and then had to pay £74 duty and tax for the import (which i had to pay after i had received the crank back). Totalling the cost at £414. You can buy other power meters for a lot cheaper from UK companies.

    • Sam

      Hi Adrian, curious to read of your experience as was looking into this as based in the UK too. What other power meter is cheaper than the total cost of £414 you paid? That aside, can you please post your experience of the power meter when you’ve tested it and which ANT+ head unit you are pairing it with?

    • Adrian Cartlidge

      You can get the Zwatt power meter for left arm crank for just £143. I would go with that and wish i had. But failing that pay the extra cash and get a new left crank arm with power meter already fitted. Not worth messing around sending your crank arm off because the money saved is negligible once you add the tax and duty. Plus if it fails you have to return it and will have no crank arm until its returned.

    • Adrian Cartlidge

      I forgot to mention – the power meter itself is ok. I had some issues with battery contact meaning that it didn’t actually work when i received it. Had to bend some battery connectors a bit but worked after that. Theres a 4iii app for android and iPhone which is pretty useless as works well with the power meter but has limited compatibility with heart rate monitors – i can’t get my polar HR to connect via BT so use strava. The data seems accurate but then most modern crank arm power meters are. I haven’t used ANT just BT.

    • Sam

      Thanks for the reply. Agree that buying the single crank from a UK dealer isn’t that much different in price especially with the weak £. And you get the support locally too.

      Back to the drawing board I suppose. I am keen on the dual sided power meter though and might wait for the release of the Dura Ace 9100 crank set with integrated PM.

    • Michael

      Adrian, are you able to zero your PRECISION via BT with the 4iiii App for Android?

    • Adrian Cartlidge

      Yes. Works better I’ve found if you hold the phone right next to the meter. Sometimes fails if it’s on the handlebars or at hip height. To be honest I don’t zero mine very often because the readings are no different when I do.

    • Michael

      Very interesting! Zeroing always fails with my Huawai and the 4iiii app! No matter how close I get to the pod. On the other zeroing works with my Polar M450 which is intalled on the stem.

    • Will

      Hi Adrian

      thanks for the info. I bought mine from Hargroves for £324, a lot cheaper. On the face of it sending off your crank arm seems cheap but the shipping on the 4iiii site seemed an awful lot and like you say, the support is in the UK this way too.

  84. Javier

    It seems this device measure cadence, but speed too? or I still would need speed sensor?

  85. Dennis

    I cannot seem to upgrade the firmware of my precision to the current one.
    I have the 0.3.0 but would want to upgrade to the 1.5.0. The app is the latest version

    • Dennis

      Solved my own issue – used our son`s phone – looks like after upgrading to the latest ios firmware, ios10 the other day, it created issues with me trying to upgrade the pod`s software, i downloaded the app on his ip5 which was still not upgraded – took less than a minute to upgrade itself.

  86. Richard S

    The link to “4iiii Precision Power Meter” on Clever Training at the end of the post is 404. Perhaps replace with link to clevertraining.com ?

  87. J

    Considering a left side version of this for my winter / cross bike.

    Couple of questions;

    re:auto zero every ride, i dont have any issue with this – but during winter when the bike is kept partially inside (porch) would it be a better idea to zero 5 minutes into ride (rather than wait outside in the cold), or would this make no difference – is the temperature at which you auto-zero important? (i have previusly read re:stages to “leave bike outside for 10 minutes before you calibrate”)

    reading through the comments i can’t seem to find anyone that has water ingress issues, is this the case? A winter through northern Europe would certainly be a good test.

    • tmr1980

      Hi – think that 4iiii recommend that the PM is calibrated 5 mins into ride so that the PM has had chance to adapt to the actual temperature.

  88. Michael Swann

    I ordered a pre-installed 105 left crank arm through Clever Training using Ray’s discount code. I have RS500 cranks on my Giant Defy 1 Disc. Hopefully the weight imbalance won’t be too bad otherwise I’ll have to buy 105 cranks as well. I found one instance where this combination worked well, so I think I’ll be okay.

    Has anyone else done the same? Has it been a problem?

    • Davesee

      Hi Michael! Have you received it yet and got it working? Seems like you’re always a step ahead of me so interested to hear how your power experience goes.

    • Michael Swann

      Not yet, it’s on a plane from Florida. I managed to beat Matthew.

    • Michael Swann

      New 4iiii received and installed. Took all of 15 to 20 minutes. For anyone interested, the weight difference is about 50 grams. Doesn’t seem to cause any static balance issues.

      My Wahoo Blue SC V2 transmits speed info by itself just fine (no cadence magnet installed on the new crank) and the 520 picks up cadence from the 4iiii. Seems I didn’t need to buy the extra speed sensor after all.

  89. Roger

    I’ve had my 4iiii for a couple of months now, it seems very reliable and I’m very happy with it.

    I did a test with a friend’s Vector 2s attached to the same crank yesterday, a 20 min ride with a few efforts showed the 4iiii reading around 9% higher AP and NP. 30s smoothed image attached, 4iiii in pink. It’s the first same-bike comparison I’ve done, could anyone explain the discrepancy? If anything I would have expected the Vectors to read slightly higher, not the other way around. Did I need to do a longer test? Is it possible that 4iiii reads 10% high, or the Vectors 10% low in certain conditions?

    I also did a 4iiii vs Limits comparison but will save that for a separate discussion.

    • That’s not too bad for a first ride, at least they’re consistent. Which makes me point more towards slight calibration things/settling. What did you do from a calibration test standpoint?

      And if this was the first Vector ride, I’d definitely give it another ride (consider this one a settling test, which is 100% normal).

    • Hi Roger,

      This is Billy here, product development leader at 4iiii. Thanks for posting your findings.

      To explain what you’re seeing between PRECISION and Vector2S requires a bit of background information. Please contact us at support@4iiii.com and I’ll be happy to discuss more.


    • Roger

      Both PMs were calibrated at the same time, right after Vector 2s had been put on. 4iiii had been on for a few hundred km, Vectors were fresh on the bike but had been used for 50ish km that morning on a different bike and have been well used.

      I’ve just seen your review of the original Vector where you suggest doing a few hard efforts and popping the battery cap before calibration – both things I did not do. I only pedalled softly to get up to required cadence and then calibrated. Could this explain the Vector reading a little low?

    • The hard efforts basically settle Vector, it’s definitely something you want to do. I’ve never seen an accurate Vector install without doing so.

    • Jacky Wong

      I am not an expert on this but I believe it is good because the reading from both PM are consistent. By the way, did you install the Vector with the required torque level?

    • Roger

      Thanks Ray, will try again at some stage.

  90. JAVI

    Which is the PIN number of the app to pair the app with the power meter? I have tried 1111, 0000, 1234… and they don’t work.

    • JAVI

      I anser my own question. When opening the app, there is no need for any PIN. It ask me for a PIN number, as I tried to pair my mobile via bluetooth in the normal way.

  91. Nathan Budd

    I was just about to take the plunge on the 4iiii 6800 power meter, and had been given vouchers for Evans Cycles in the UK so that I could buy it.

    I’ve gone to the site, and for the 6800 the 172.5mm version is missing (they only have 170mm & 175mm) and the reply from Evans is “Unfortunately, our stock system indicates that this size is discontinued by the suppliers.”. Any news on this? As ProBikeKit in the UK only has the 165mm and 172.5mm.

    Has anyone heard of the Precision being discontinued? I don’t want to buy a legacy power meter. If needs be, I’ll spend the extra and pick up the Pioneer single side.

    • Chris

      4iiii’s website still shows them available but Clever Training website says they are not. You could send 4iiii an email and they may let you know what is going on.

    • Pearl

      Production of PRECISION is going full tilt as are our orders. We have just shipped a large quantity of the Ultegra FC-6800 172.5 to our UK distributor and they should be with Evans Cycles shortly. We’ll ask them to modify their out of stock message; thanks for bringing it to our attention.

    • Vitaliy

      Pearl, from what I understand dual side power meter is not available for Cannondale SI cranks. Any plans to add dual side option for Cannondale folks?

  92. Peter

    I’m in the market for a new power meter and am considering the 4iiii dual sided. Any idea when you will have the in depth review posted on this? Apologies if you have already mentioned this and I’ve missed it.

  93. Niall

    Just a quick comment on my experiences with a Precision single sided Ultegra unit – bought from Evans in the UK – went through the motions of fitting, updating firmware and calibrating – all went fine but when testing I saw no power readings – Cadence was fine over ANT+ and BLE but only very occasional sporadic single digit power numbers. Few days of email exchanges with Pearl at 4iiii support and despite some suggestions and things to try the issue couldn’t be resolved remotely. RMA Process started on a Thursday with prepaid Fedex documents emailed to me – Dropped off at Fedex on the Friday morning – transatlantic trip over the weekend and arrived with 4iiii on the Monday. Unit repaired and shipped by Friday, back with me on the Monday morning. Refitted to the bike and working fine now.

    Now obviously It would be great if the PM had worked out of the box but crap happens and as far as service and support goes I am impressed by the way it was dealt with. Thanks Pearl!

  94. Michael Swann

    I bought one of these and have only had it a few weeks (bought through Clever Training using the DC Rainmaker discount code).

    I’ve noticed some rather large power and cadence spikes at times. They seem to occur when I stop pedalling to go over train tracks. On my normal route to work I go over train tracks on four separate occasions. I usually stand on the pedals with the crank level and my knees bent to absorb the vibration.

    Tonight I saw a spike of over 2000 Watts.I cleaned up the file with an online tool to remove the large spike, but I still have the original file if need be.

    Is there a trick to avoiding these spikes or is it an issue with my particular power meter? It’s running the latest firmware.

    • Chris

      Sounds like power meter is doing its job. It is seeing the shock going over the tracks if standing with crank horizontal to ground. Try putting the left crank at 6:00 and see what happens or put the left crank facing towards back of bike.

    • John

      You’re looking at a 3 second or 10 second average power, right? Instantaneous power numbers tend to not to be very useful…

    • 2,000w is definitely odd though, filtering should be taking care of that. I’d reach out to 4iiii and send them the files to see what they think.

    • Michael Swann

      I wasn’t looking at the numbers when I was riding. I didn’t see the peak until I reviewed the data after upload to Garmin Connect. The peak showed up also on Sport Tracks and Training Peaks. Strava filtered it out.

      Strava also filtered out the wonky speed data that I got from my Wahoo RPM Speed Sensor as well. The speed sensor is a separate issue. I don’t think I really need it as the GPS data from my Garmin is better than the data I was getting from either of the Polar devices I owned, which was why I put the speed sensor on in the first place.

      I will follow up with 4iiii and see what they say.

      As for trying other positions, that will have to wait till the next time I ride to work, which will be next week some time. Standing and putting the left crank at 6:00 sounds like the way to go, puts all the load in the crank purely in tension.

    • Michael Swann

      I received a response from 4iiii. Apparently what I’m seeing is a known issue and is to be addressed in the next firmware update to the Precision.

  95. Roger

    How are people finding the battery life on 2nd gen? I got my first low battery warning yesterday, the app says 8% left and I’ve only done 58 hours on it, a little less than half the quoted 120 hours. Am using the standard panasonic battery that came in the box.

    • Jacky Wong

      Same here, I replaced the battery yesterday(the spare battery in the box). And I found it shows 50% full.

    • dennis

      Hi Jacky,

      Did you click on forget the device before re- pairing the pod with the new battery? i read it somewhere that it automatically shows 50% if you put a new battery but keeping the same pod paired

    • Jacky Wong

      Oh I see, let me try when I arrived home.

    • Pearl

      Hello Roger
      This is a known bug with firmware 2.0.0. We are working this and are close to a solution. The readout is not reflecting your true battery status – it actually isn’t draining at that rate. However you need to override the reader status by taking out your battery and reinserting at the start of your ride. This is a temporary workaround and we will have a firmware update in the app stores soon. Thanks for your patience!

    • Roger

      Thanks Pearl. That makes sense as I’m sure I was > 50% remaining a couple of weeks ago before the firmware update. I’ll put my bulk purchase of cr2032 batteries on hold!

    • Bogy

      I just bought a 4iiii Precision Power meter and I am planning to use it with my iPhone. Can anyone share what ios app is best at recording both the power and cadence data from the device?

    • Eric

      It works fine with Strava and many more. But instead of a Smartphone-App, I use most of the time a cycle computer like the Garmin Edge 520.

    • Bogy

      Strava app does not work well with the 4iii Precision Powermeter. First it does not report cadence. Second, on the devices screen it shows Power in rpm and during a ride the reported power is not accurate so it is either calculating it based on cadence or it is reporting cadence as power.

    • Roger

      I’ve had no problem pairing 4iiii with Strava on Android, using ANT+. Cadence works as expected and power looks pretty much the same as it does on a Garmin recorded ride. I keep my phone in my pocket so I can’t comment on how it looks during the ride, but the saved ride after has everything you’d see when pairing to another device.

    • 4iiii Innovations

      Please pair PRECISION with the 4iiii app and enable 3rd Party Compatibility Mode. Your Android device needs to support Bluetooth 4.0 or higher.

    • Bogy

      I did pair mine through the app (I am using iPhone 6) and it works great with Cyclemeter, Zwift and other 3rd party apps. The only issue seems to be with the Strava app. I submitted a Support Ticket with them to see if they have any suggestions.

    • Bogy

      After a few back and forth emails with the Strava support team they were able to recreate the issue that I have with the Precision Power meter when using the app and Bluetooth. They acknowledged it was a bug. They said they will address it in the future updates (hopefully soon). They also said that although the cadence is not shown on the main screen it is recorded by the app and can be seen when you upload the session to Strava website.

  96. ekutter

    I’m considering getting the 4iiii left only PM. I have DA 9000. Is there any benefit to buying it with the crank arm for $599 (minus 10%) vs sending in my own crank arm for $399 (plus $41.94 shipping to Oregon – yikes)? Would I expect identical accuracy?

    Also, do you know if they have any plans for SRAM XX1 Eagle on the mountain bike side?

    • John

      I think for most people it comes down to whether or not they would be without the use of their only bike while their existing crank arm was off to 4iiii being retrofit.

    • John

      Of course at the 105 level, the price is the same so there’s almost no reason not to get the Ride Ready version…

  97. Dennis

    Thanks for keeping this thread running.
    Been using mine for 11-12 weeks now – have been getting low power readings which I thought might just have been fitness related. Did all the good stuff before each ride – on my head units, started with the 920 and went to the edge 500. I would also calibrate via the app and trainerroad. This week the update came out, updated the pod and then road the trainer without thinking about the update, I did notice my power was higher than the previous ride this week. anyone had the same thing happen to them recently?

  98. Mark

    Anybody know what the latest 2.1 firmware for the 4iiii does? I’ve got the 105 crank and very impressed so far. I had a slight issue with power dropping out when climbing with a slow cadence and high power. I paired with the Android app and the issue seems to gone.

    • Dennis

      From Pearl
      The firmware update (version 2.1.0) includes bug fixes and improvements that provide more reliable power data in some riding conditions. In addition, battery reporting has been adjusted on both the firmware and the iOS 4iiii App (version 1.24.0) to provide a low battery warning when there is 10% of battery life remaining (compared to 8% in version 2.0.0).



  100. Steve D

    Just ordered a 4iii, 105, left side only through clevertraining so Ray can eat and keep making awesome reviews. I’ve got a powertap hub and am anxious to see if my previous PT data will essentially be useless when compared to a left side only. I’ll do a bunch of same bike tests and report back. If it’s way off I may return the precision and get the dual sided version. Also seen nothing about the lezyne computers and the 4iii so hopefully that works without issue.

    • Pearl

      Hi Steve
      I’d advise you contact Clever Training to verify their return policy. Cranks that have been used cannot be resold. You can, however, always upgrade by adding on the right side FC-9000.

    • Steve D

      Shoot, I didn’t realize that. I don’t have dura-ace cranks so upgrading to the dual sided is not really an economic option. I took the precision and the powertap on an indoors rollers ride yesterday and was less than pleased. It may be just the reality of left-side only, or because I didn’t let the precision settle before calibrating it, but the precision generally read low, sometimes 10 watts, but sometimes 25 watts. I saw generally because the precision was around 3% lower than the powertap, but on one 2 minute interval it was only .5% lower. I would expect it to be the other way around, given that the PT hub is farther from my foot. I also could not set the crank length and calibrate with ANT+ on my lezyne enhanced super gps. I used bluetooth instead.

    • Steven D

      After a dozen rides with the Precision, I’m very pleased. By fiddling with the offset values after about every ride through trial and error (my left leg is pretty consistently 1-1.5% weaker than my right) I was able to get the precision to track within 1% of my powertap across easy and hard efforts, and sprinting/climbing is consistent too. If I consciously try and flick my left leg down, the precision will read higher, but that’s a reality of left side only power measuring.

  101. asimon

    After reading that the battery reporting was updated in the 2.1 firmware update, I went into my box of used 4iii batteries and reinstalled one. (i changed them out @ 5%~1% remaining battery life) The original battery that came with the unit is still working 27 hours in.

    Reinserting the battery will display 50% remaining life and subsequent rides will show 0%. Power data is consistent compared with a full battery.

    • Dennis

      Safe to say you clicked on forget the device before putting the new battery in then pair it again with the app. Mine showed the same % before.

    • Roger

      Is anyone getting close to the 120 hours advertised battery life? I got 60 hours on my first battery, and now have had to replace the next one after just 40 hours. I replace them at 1% so I can’t imagine there’s much juice left in them.

  102. Arran

    I recently got the Ultegra 6800 precision, whilst I’ve never used power before it’s nice to see a power number now.
    However I am getting some strange readings, like when I am pulling off at a junction and give a little bit of grunt, I’m them registering 160+ cadence and 1,300w+.
    Clearly I’m not achieving these numbers…so I have no idea why it’s glitching. It does it an awful lot when I am pulling away from junctions.
    I’ve emailed 4iiii about it, however haven’t received anything back from them yet, but hit record cadence and power today whilst at about 0.9mph!

    • Have you tried doing re-doing a zero-offset (aka calibration)? Almost sounds a little like perhaps during a previous calibration there might have been load applied to the pedals.

    • Arran

      Trouble is I am re-calibrating it before every ride, as I have the Garmin prompting me.
      Always reports Successful and 0 torque on the crank arm.

      Checked and double checked the firmware, on 2.1.0.

      I wasn’t aware of the funky power numbers before, was just concerned by it giving me at a minimum 140 cadence each ride, but today giving me 1377w and 164 cadence…just sounds barmy.

    • dennis

      Happened to me as well on my first ride out on a 1000+ watt output, if i am riding outside, i calibrate via my garmin and also via the app – have not had any instances since.

    • Arran

      Unfortunately I have got super high cadence when calibrating with the app or with the Garmin.
      Shouldn’t really be due to any big temperature shift, as it’s cold in my garage and cold outside…!
      Guess it’s a wait for 4iiii to get back to me.

    • Agree, sounds like something else is amiss. Usually 4iiii responds pretty quickly. They’re located just outside of Calgary, so probably another 6-8 hours before they’re in the office today.

    • Pearl

      Hi Arran
      Our support team is on it! Typical response time is 24 hours.

    • Arran Jacobs

      4iiii have advised to return to the place I purchased it under warranty.

      So now have to jump through the hoops of the ProBikeKit warranty procedure.

      Definitely something up with the unlit, was reporting 138 cadence at 0 watts, then 0 cadence at 0 watts, then 85 cadence at 0 watts for about 150m.
      I’m presuming it’s just a bad unit that I’ve received, hopefully get a perfect one next time :)

      Now to go jump through some hoops…

      No Zwift for the next week or two :(

    • Arran

      Got my replacement unit today, so hopefully test it next week!
      Will report back my findings, hoping it doesn’t give me the same crazy readings!!

  103. Paul


    Thanks for the extensive review, great stuff!

    Any chance that the coupon code for clever training will be made available again soon?

    It seems to be expired.


  104. Arran

    Back again!

    Sent my 4iiii back under warranty, and received a new unit.

    I have the same issue…
    Prime example today –

    Halfway through my commute, stop at the top of a small hill to adjust my shorts.
    Pulled away from the kerb and all seems fine about 890W and about 86 cadence whilst pulling away, completely normal…

    Then I can only decipher that when I then get back in the saddle and stop putting down power, power goes down to like 70w when going from standing to sitting, but cadence seems to double and go to 140 – 160.

    Then power and cadence normalize to around 180w and 95 rpm….

    It’s as if the unit just goes mental whenever you freewheel for a second?

    Looks pretty buggy to me….

    • Bogy

      If you freewheel it is normal for the power to show a sudden decrease and for the cadence to go up: it’s what actually happens, you apply almost no force on the pedal while you spin very fast. If you want more normalized values displayed for the power you can set your device to show the average power over 5 seconds or more (depends on what you use to display the power, some apps don’t allow you to do that). I don’t think it’s a bug, it sounds like normal values to me.
      I hope this helps.

    • Arran

      I think you misunderstand…
      My cadence is never 150 – 160 (hell I’d know if I was doing that kind of cadence), and transitioning between standing and sitting my legs would slow down rather than speed up…and it’s around that time that it’s malfunctioning.

    • Arran

      Ok, so received a response from Pearl at 4iiii. Not exactly a positive one either:

      1) There is a known cadence spike issue
      2) It’s doubtful it will be fixed in the next 6 months
      3) It’s software related the more prevalent in some head units / watches
      4) Can’t advise what head units / watches it’s more prevalent in
      5) Try a different head unit…..

      So all in all, It’s a known issue, fix in the next 6 months is unlikely, go buy a new Garmin – you might be lucky enough to select a head unit that it’s not a problem on….

      Well I am probably going to return the 4iiii and go with another brand now, as that response in my eyes is not really acceptable for a unit costing £469.

    • Philip

      What head unit are you using?

  105. Hi Arran,

    Thanks for supporting 4iiii through your purchase. I’m the product manager for our PRECISION line of products.

    We have been running the same production firmware across all our Pro Tour teams and sponsored athletes over the last 6 months and have not received any complaints of cadence spikes from our teams and athletes. Currently, our UCI World Tour teams are using their PRECISION PRO powermeters with Garmin Edge 520 bike computers.

    Internally, for ANT+ testing, we use a wide range of bike computers including the last two generations of Garmin bike computers such as the Edge 510, Edge 520, Edge 1000, and Edge 810. Based on our testing of the current production firmware (version 2.1.0) and day-to-day usage, we have not observed issues related to cadence spikes. However, we have observed cadence spikes when testing with older generations of Garmin bike computers.

    We always value feedback from our customers. To this end, we are happy to work with you to resolve the issues you through our customer support. As part of this process, it would be most helpful for us to know what bike computer(s) you are using for which you are seeing this problem.

    Billy Chan

    Product Manager

    • Michael Swann

      I see cadence spikes on my 4iiii Precision. Had multiple spikes on Sunday’s ride which was 92km with only three stops between start and finish. I use a Garmin Edge 520 and it is running the latest firmware (11.10).

      I’m contemplating what to do next. I have drafted an email with my ride data to send to 4iiii for them to look at. It’s got me wondering about whether my unit has a problem or whether what I see is normal.

    • Arram

      Did you get a resolution to it Michael? I use a 520 as well…

    • Michael Swann

      I haven’t sent the email yet, but I think I have identified what causes the power spikes in my case: they seem to occur every time the free wheel engages.

      I get power spikes when I start pedalling again after coasting. I noticed this when reviewing today’s data. I had nice, consistent power data for the first part when I was riding into a slight head wind and was constantly pedalling. Later on, when my pedalling was stop-start, I saw spikes in power at the corresponding times when I start pedaling after coasting, even if I only coasted for the briefest time.

      I guess I need to be more mindful of my technique and gear selection.

    • Michael Swann

      I sent the email and got a response which said try doing a whole heap of different things (check the firmware, check the contacts, take the battery out and put it in backwards, re-pair the sensor). I’m doubtful whether any of that would help.

    • Micha

      Does this nonsense ever stop?

    • I’m not exactly sure you can blame a company for double-checking known problem solving troubleshooting.

      The vast majority of times people arrive with questions, they’re solved by easy things. Seems a logical first step to me. Also note that the first two of Michael’s comments were discussing on drafting an e-mail, he hadn’t actually sent said e-mail till the last e-mail. Nothing wrong with that, but it’d be mistaken to think there was three correspondences there.

  106. Brad

    I received and installed my Precision 105 5800 today.

    Upgrade firmware? Check.
    Calibrate/zero? Check.
    Works nicely? Fail.

    Unfortunately the power reading is around a factor of 10 out – 20W when I know the gear/cadence combo I’m using on my turbo normally gives around 200W (measured with a Stages G2).

    Anyone else seen similar problems and if so did you manage to resolve it and how?

    • Peter

      I recently purchased a dura ace version (ready to ride option not fitted to my existing crank). I have had inconsistent results with it generally under-reading compared to my Garmin Vectors (sick of moving the vectors between 2 bikes and thought this was a relatively inexpensive way to get reliable power on both bikes). The variance isn’t consistent though, at times the 4iiii reads 10-20% less than the Vectors and sometimes over short periods it actually reads higher. I am reasonably confident that the vectors are accurate (or not too far off) as I get consistent readings for similar speed rides over the same segments and they have given similar results to other power meters I have used.
      I raised the issue with 4iiii and got a response that there was always differences between power meters and that I should use the factoring to adjust the 4iiii to match my other devices. Given the variance is inconsistent I didn’t think this was a helpful response. I have since provided fit files of rides where I had both meters installed uploading to separate head units but am yet to receive a response from their support.
      I’m very disappointed in the product and even more disappointed with the support (I would be happy to work with them to get the issues resolved but that doesn’t look like it’s going to happen).

    • Two quick questions:

      1) For Vector, what are you torqueing the pedals to? And are you redoing calibration after a ride with some short sprints?

      2) If so, do you have any comparative data files (after 1-2 rides)?

    • Peter

      Hi Ray,
      1) I always torque the Vectors to 300nm and recalibrate after a short ride and before every ride.
      2) yes I have data files from both power meters from the same rides saved on my PC.

      I have also ridden with the Vectors and a Verve Info crank and obtained very close results.

    • Cool. If you can either post the data files or shoot them to me, I’d be interested in running them through the Analyzer.

    • Pearl

      Hi Peter

      Our apologies that your request was not responded to by our team. I have escalated this to a high priority and the customer service rep who is handling your request will be replying today.

    • Peter

      Hi Ray,
      As per Pearl’s comment below 4iiii have now responded and the unit is going back to them for testing.

      Will email the files through as I can’t post them here. My ride files from this morning’s ride a 2 hour ride before work – 4iiii connected to an Edge 510 showing average power of 174w and the Garmin Vectors connected to the Wahoo Elemnt showing average power of 233w :

      I also have files from an interval session on the weekend with several laps which shows swings in the variance lap by lap if interested.

    • Peter

      Hopefully the files are attached this time.

    • Ivan Vukomanovic


      I would be very intrested in your outcome. I have a very similar issue to you. 4iiii have told me to adjust the left/right balance to compensate, which is not a satisfactory answer. I currently have to run my precision at a 1.13 ratio to get a power reading similar to my elite Drivo.

    • Micha

      Odd! This is getting even more strange. The PM is delivering wrong values. So why not compensating it by shifting the left/right balance setting…

      At least it seems that yours is delivering constant values (even if they are wrong). But how useful is a PM delivering values deviating about 60W from one reading to an other if you’re steady cycling?

  107. Cristi

    Just got a Shimano 105 unit for my wife & when I shake it it rattles like something’s loose inside it (link to youtu.be). I’ve removed the battery and the cover and they’re not to blame. It’s also definitely not the screws or the locking part. Did anyone notice that kind of a sound ?

    • Niko

      I noticed that too when I installed my 105 5800 power meter. Seems to be working fine though… Did you ask manufacturer/someone is it suppose to do that and is yours working ok?

    • Pearl

      It is likely that the bolts are loose in the crank and this noise will not occur once the bolts are torqued. Alternately, the safety retention clip may not hooked around the bolts when fastened to the spindle. For additional support contact support@4iiii.com.

  108. Adrián Chapela


    What about Sram X9 BB30 crank?

    Do you know if there is any plan?

  109. Martijn

    Can you use the 4iii also with the Garmin forerunner xt 735?

  110. NathanC

    I got two rides in with my 4iiii Precision and the second ride was in a bit of drizzle. Hasn’t worked since then and I am getting a little sick of the back and forth emails asking me to bend out the battery prongs, try different batteries etc. The 4iiii app is clearly not recognizing the power meter… Wondering where how this will pan out with 4iiii.

    • Micha

      Yes great! I know these questions: Please ensure that the battery has it’s full capacity, please check if the prongs make good contact…

      I had to send my crank three times to 4iiii until I got one that was responding to the 4iiii App.

      I’m using it on my Shimano DA FC-7900 crank (V2 left side version) since 6 month now and I have to say that it is an expensive piece of scrap!

      Riding on a flat with constant speed, constant cadance, constant heart rate, no corners, no changing wind (let’s say lab like conditions) the measured power is deviating in a range of 60W on an average of 200W! Even with a high filtering time choosen in my head unit (5s, 10s) it’s impossible to use this for controlling your intervall.

      Let’s get it to the point, taking into account what can be read in several postings here: It simply doesn’t work!!!

    • Pearl

      Interesting – we don’t support install on the 7900 crank and have never had a unit returned 3x. We would like to resolve your issues, please contact us with accurate information at support@4iiii.com.

    • NathanC

      You’re replying to Micha but not me. My crank was one bought from 4iiii so it came installed on the crank already. I have tried 4 different batteries and these same batteries power some lights I have and work flawlessly in my Quarq on another bike. I have done every tiny silly thing Jerold from 4iiii has told me to do yet here I sit with a two week old power meter that doesn’t work. I would like a replacement ASAP.

    • Micha

      Yes indeed, very interesting! So if 4iiii never installed or supported PRECISION on a FC-7900 crank I wonder where I got this from!

      Obviously this is a 4iiii PRECISION left side PM installed on an FC-7900 crank.

      And by the time I ordered it via clevertraining.com the FC-7900 was on the list of supported cranks published on your website.

    • Micha

      1st device (V1) received April 2016:

      This unit didn’t communicate properly via BTLE. I spend lot’s of hours trying different head units, smart phones and apps without any success.
      Meanwhile I recived some battery caps from 4iiii and did all the silly things proposed. Of course without any success.

    • Micha

      2nd shipment June 2016:

      I received the same unit back. Of course with the same fault. Obviously 4iiii wasn’t able to understand my claim.

    • Micha

      3rd shimpment July 2016:

      I got the V1 replaced by a V2 shown in the picture above. This can now be connected via BTLE but is delivering unreliable data.

      So Pearl, did I count right? Are these three times I had to ship my crank to 4iiii with all the hassle uninstalling/reinstalling it? Spending hours of trying anything to make it work.

      Never ever try destroying my credibility again by posting false pretences like the FC-7900 wasn’t supported by 4iiii or you can’t remember having a crank arm shipped three times. I’m just reporting facts!

    • Brantel

      Kinda hard to argue with that much data to back up the claim… LOL!

  111. Arran

    Two 4iiii Ultegra units, both giving Cadence spikes, to the point last weekend it reported me spinning at 216RPM….

    Spoken to Pearl countless times, apparently was going to be added to the “Beta Team” to get some Beta firmware and see if this would help my cadence spike issue, alas this never came about, even though Pearl told me the paperwork was incoming and I would just need to return it to get the new firmware.

    I chase her yesterday, that myself and my high cadence figures are waiting for her…and she doesn’t even bother to read the email chain that we’ve had previously and “presumes” I want to send my unit in for repair.

    I mean come on…it’s a £469 piece of hardware that can’t even report cadence accurately, which my garmin crank arm sensor has done accurately, all for the price of £40 inc speed sensor.

    Needless to say I’ve lost all confidence in 4iiii and their staff, I am requesting a warranty refund with ProBikeKit, as this product is unfit for use.
    What a crying shame, that they couldn’t get something so simple, right…

  112. Steven D

    I’ve now had my 5800 precision since December now and thought I’d provide an update. I switch it between two bikes on average once a week. I’ve ridden it in some pretty nasty conditions and have seen no adverse affects. I’m on my third battery and ride 9 hours/week average. There are some bluetooth dropouts between this and my lezyne headunit, but fewer here than on my wired powertap. 2032 batteries don’t like below 25 degrees fahrenheit either, so I lose power readings after an hour or so of winter rides here in MN.

    My only complaint is that the battery guage is worthless. If you take a used battery out and put it back in, it shows 100% battery. I’ve accidently popped open the battery compartment when changing the pm from bike to bike, so I end up just replacing the batteries proactively before big events. When my first battery died, the guage still showed 40% even though I hadn’t opened the power meter at that point. So even that was incorrect.

    Still very consistent readings between this and my powertap hub. There is a slight delay, about a second, when putting power down, but I think that’s the nature of a left side only power meter.

  113. Javier

    I’ve been using the 6800 4iiii precision power meter for about 6 months without issues (at least that I have noticed), but today it has recorded a very strange power outpout spike.

    I don’t think I have produced 1141 W in a flat road at 16’5 km/h 2’45” after starting my ride… by the way, yes, I have calibrated it as I always do, in the street (to match the temperature).

  114. ekutter

    I just got a left only Dura Ace 4iiii power meter from Clever Training. There’s a lot to like about it, mostly how easy it is to install and how light weight it is.

    After several tests, I’m seeing very consistent but odd numbers. I’ve compared it to 4 other power meters: Kickr v1, SRM, Powertap G3, and a Computrainer. In all cases, after proper calibration of all, it reads as follows:
    The kickr/SRM combo stay within a couple watts of each other as does the Computrainer / PT combo.

    under 220 watts – 4iiii overstates power by 13 to 18 watts (similar offset whether it’s 150 or 200 watts, so not percentage based).

    220 – 270 watts – 4iiii reports from dead on with the others to 13 to 18 watts over. Seems more accurate with a quick pick up to higher wattages than a steady state at the higher wattage

    over 270 – within a couple watts of the other power meters. Max wattage from 600+ watt sprint is usually within a couple watts.

    So I can’t even really set an adjustment factor to fix the lower wattages since it would mess up the higher wattages.

    I don’t have a pedal based power meter to measure my left right balance but I doubt I would see this kind of consistent imbalance, especially across a range of cadences and fatigue level.

    My SRM is actually a Dura-ace 7800 crankset so at first I thought that might be part of the problem but then saw the exact same results with it on the Dura-ace 9000 with the Computrainer and Powertap wheel.

    Has anybody else seen something similar or any other suggestions?

    • Cristi

      It might be just be the fact that the Precision is left only and doubles that power. Based on the load, you might not produce exactly half the power with the left leg, which might explain the differences you mentioned.

  115. Ste Aldo

    Been looking at buying a power meter for some time so after countless review reading I opted for the 4iii because it was within the price range I was was willing to pay. I bought the shimano 105 5800 left crank arm from Ribble cycles it seemed to work fine for about 1/2 a dozen rides although I did notice the cadence spike on my max cadence numbers. However on my last ride I registred very high power numbers 3x higher than normal this did concerned me but thought maybe it was a one off so before the next ride I checked the torgue on the bolts & then tried to calibrate the unit first via the app on my phone it failed then I tried on my Garmin 520 which it also failed on. I phoned ribble & told them the problems I was encountering they told me they had had about 5 units sent back with the same problem. I have opted for a refund because I would rather have no power data than wrong power data

    • Arran Jacobs

      Here Here….finally other people are having the same issues as I was.
      I am happily riding without power now, until something better comes along.

  116. Jacky Wong

    My left leg 4iiii was working properly until last night. In the middle of the ride, it stopped to show power and only shows cadence. Anyone has similar issue? I am using Garmin Edge 510.

  117. Josh

    I ended up getting a 4iiii Precision Power Meter, and it has been working great. Love that I don’t need a cadence sensor anymore. I ended up buying a Wahoo speed sensor, too, so I could get rid of my Garmin GSC-10.

    My bike has Shimano 105-5700 components. I bought a ride-ready Shimano 105-5800 left side crank from 4iiii for $399. I wasn’t sure how well it would match. Well, it turns out that 5700 and 5800 left side cranks are absolutely identical. I don’t think they changed the design at all. Score!

    I had a time trial this past Tuesday. I rode this course last August for the first time (first time trial in 25 years, too), and turned in a time of 28 minutes flat.

    This time, I had my Garmin Edge 1000 telling me how far ahead or behind I was based on Strava Segments. Ironically, I thought I was behind the entire time, because it turns out that I had ridden 2 roads of the course with some friends in a pace line, and those were my best times, not the times from my last time trial.

    My result was 27:16. I definitely needed to concentrate more on the riding, because I caught my heart rate falling to 171 a few times, and I wanted to keep it between 175 and 180. My average power was 204W. I definitely want to push that up with training.

    I had a GoPro on my bike for the ride, and I overlaid my Garmin’s sensors over the video using Garmin VIRB Edit. I think it came out really well:

    link to youtu.be

    Here’s the Strava ride:
    link to strava.com

  118. Fran Jiménez

    Have somebody tested with a Polar V650?

    I have read that that works good, but when I search information in the official web say that it’s not compatible.

    Thanks and regards. Fran.

    • Micha

      THe V650 doesn’t work with the 4iiii PRECISON. I had one and had to chnage to the M450. also the new M460 is compatible, I strongly recomend t go for the M460. The V650 has no signbificant benefit and the M460 is slightly improved compeared to the M450. E.g. the buuttons on the M450 are to small and impossible to operate with gloves.

    • Fran Jiménez

      Thanks, Micha. Finally I’ll buy the Powerpor that it is tested with de V650.

    • David Chrisman

      Fran–I was looking at 4iiii as well but went with Powertap GS hub since 4iiii wasn’t supported for V650. Been using Powertap for 3-4 months now–no issues yet. Are you wanting V650 for mapping or larger display?

    • Micha

      Good decision considering all the issues 4iiii PRECISION has (just read all trough this page…). Don’t know about the Powerpor you mentioned, but the 4iiii is way below my expectations.

    • Micha

      Maybe this fit’s more to the V650 review:

      I found the display of the V650 hard to read and the map is so small that it’s very difficult to navigate. But this might be my personal problem, as I’m getting older and my eyesight get’s worse :-). That’s why I “downgraded” to the M450 (beside 4iiii compatibility).

    • Fran Jiménez

      Thanks for your advice. ;)

    • David Chrisman

      Yes it just depends what you are looking for. I have no problems with display on V650 and the color display is nice. I’ve used the routes once and it worked well and it is nice to be able to download a 450km x 450km map on to the unit that you can reference if lost (I ride locally so again haven’t used that much). So if you are happy with current features and price is good it is something to consider–same with M450. DCR does have a V650 first look post as well as hands on for M450 so it would be worthwhile reading those posts (especially the discussion section). I’m guessing you will not see new features on either V650 or M450 in the future as Polar seems to be focusing efforts on M460. If you have any other questions on V650–post a comment to V650 first look post and I will happily give you any help I can.

  119. Vleermuis

    I’m getting a bit concerned with some of the issues reported recently by other readers. I recently received my second 4iiii power meter, bonded to a Cannondale Si crank, after having a 4iiii PM bonded to my SiSL2 crank in August 2015. After installing the Si crank to my second bike (CAAD10) I immediately noticed that achieving the same power numbers as with the SiSL2 crank was much more difficult. I was blowing up just riding for a few minutes at my (SiSL2 measured) FTP. I decided to put the bike in my Tacx trainer, testing both cranks on the same bike, same gearing, same resistance level, doing the same intervals: 2 minutes, 36km/h avg, 90 cadence avg, 53×19 gearing (travelling a distance of 1.22km each interval). The 4iiii Si crank measured these intervals at 218-220w, while the 4iiii SiSL2 crank gave 255-259w average. On balance a difference of 38w, or ca. 17.5%. So, I have two cranks with the same power meter, same firmware but wildly different output.

    I highlighted this issue to 4iiii and the response was that consistency is key, that different cranks measure power differently (“a Shimano 105 versus DA9000 crank would also have different measurement”) and an explanation on how to change the scale factor on either of the cranks to align it with the other crank. That response is not good enough. Consistency of measurement is important, yes, but please let’s start with those measurements being accurate. If I put out 200w, I want my PM to tell me that I’m doing 200w (within the1-2% error margin, not a 17.5% error margin).

    In essence, I have no idea which one of PM’s measures correctly. It might well be that all my power data collected the past 18 months from the SiSL2 crank is worthless. I’m in touch with 4iiii and hope to have this resolved. In terms of actual data collection and consistency both PM’s have been fine. But there’s no point in consistently collecting inaccurate data.

    • Michael Swann

      There could be something in what you say. The flex of Dura Ace crank will be different to that of Ultegra and will be different to 105. If the firmware is optimised for Dura Ace, then it is likely that power readings will differ for the lower spec groupsets. How it might differ, I couldn’t say.

      The only reviews I’ve seen online are of Dura Ace cranks, so who knows how the other versions compare.

  120. Micha

    The leading german cycling magazin “tour” had several PMs on test in their latest issue. They are highly reputated for their scientific approach running test. 4iiii was invited to take part in this test with their PRECISION PM. But they didn’t even response!
    Putting this together with all the issues reported here it’s very likely that they are not interested in having an impartial look on their device.

  121. Karl

    my 4iiii is dead now :-(

    during the change of the battery the contact plate fall off. Just sent a question to 4iiii support if they have any idea what to do.

  122. MattJ

    Anyone install a 4iiii Precision PM (Ultegra 6800) on a Trek Madone 9 Frame? Or verify that it does/does not fit clearance-wise? Thanks

  123. Bogdan

    I bought the Precision single side Power Meter in November 2016 and was pretty happy with it (being my first power meter and having no basis for comparison).
    At the beginning of August 2017, in the middle of a ride, the power reading dropped about 100W while the cadence reading remained consistent with previous rides. I continued testing it for a week or so (zeroed it several times, changed battery etc), going on familiar Strava segments and comparing with previously recorded output to convince myself that it is really a problem with the device and not my legs.
    I wrote to 4iii to ask for help and I am pretty disappointed with the level of support received so far. I have explained in my first email the issue that I have with my PM, sending them links to the rides and data and explaining in great detail the steps I took to convince myself that the unit is defective. The 2 replies I got from 4iii were 1 day apart (even though I answer their questions almost instantly) and contained trivial standard instructions (like “enable 3rd party app”, or take battery out and put it back in) followed by a long silence (3days + the incoming weekend). It is really frustrating to have a defective PM and be ignored by customer service. Reading previous comments I saw that posting here helps, I hope to hear from a representative soon. My case number is 30673 and the person handling it is Jerold.
    And if anyone else experienced a similar issue and found a solution please help.

    • Brandon

      I purchased the PM in June and I have no complaints at all. The customer service was great and they responded quickly to my e-mails. I couldn’t happier. Hope this all works out for you.

  124. Kevin Purcell

    I’ve been using 4iiii precision gen 1 units since their release. One gets swapped between my road bike and cross bike and one between my mountain bikes. They’ve done thousands of miles of training and racing in all sorts of conditions here in the UK and abroad. Never had a single problem with either of them and would get another in a heartbeat.

  125. Mike G

    I bought one of these from CleverTraining and it came scratched and looked used. So I asked for a replacement. They sent me a 2nd one and it was scratched exactly like the first. (Too bad I didn’t note the serial# of the 1st). The scratches were pretty much identical to each other. So I emailed them about it, as it seemed they just sent me back the one I just returned. Customer Service is telling me that both cranks are new, and not the same. I find it hard to believe that two cranks would come from 4iiii, scratched the same, let alone be scratched and look used. Has anyone else experienced this with their crank?

    • Eli

      4iii has to take new cranks from Shimano and put on their power meter which I’m sure involves mounting them to test and calibrate making it slightly used. So why would it be hard to imagine they would be scratched the same if they were handled the same? Also guessing most people care more about using their cranks than small hard to notice scuffs

    • Odd, I’d agree not ideal.

      Eli noted one portion – the other is that 4iiii used to actually go for test rides with all units (just a few mile circuit). I believe that then slid to a certain percentage of units.

    • Henry

      Ray – I’ve been seeing some inconsistent power data recently, not on all rides but randomly. I’ve uploaded an example ride to the DCR Analyser: link to analyze.dcrainmaker.com
      From what I can see it looks like the power meter is dropping communication, what’s strange though is that on my Wahoo Bolt during the ride power data looked totally normal and the post ride summary on the Bolt showed realistic power figures:
      Avg PWR:246w
      NP: 276w
      5 Sec: 1126
      30 Sec: 524
      1 Min: 436
      5 Min 308
      20 Min 267
      30 Min 260

      Do you have any ideas how that could happen or have your experienced this kind of behaviour before? Battery was showing fine but I’ve replaced that for good measure anyway..

    • Henry

      I’ve been doing some further testing and research and it looks like this problem is related to the latest firmware on the Wahoo Bolt, a number of other Bolt users have reported similar ANT+ drop outs after upgrading to the latest firmware having had no previous issues for a year or more. I’ll post over in the Bolt review but if anyone else has had the same experience it would be good to know if you’ve been able to get a resolution from Wahoo.

  126. Dennis

    For the past few months, always felt power i was seeing was lower than normal and read the manual again and learned about adjusting the scale factor which for most their right leg was stronger. In my case having a bum right knee for almost 30 years, it has not been able to catch back strenght wise. Do i use the same formula they used given my left leg is dominant.
    Mine is 55/45 with regard to left/right %

  127. Jim


    I’ve purchased the 4iiii Precision 105 5800 power meter on the 6th Sep and I can connect to my Garmin 510 and the app by 4iiii. The first 2 rides using the power meter shows some readings from the PM until last week where 0 W reading was displayed half way during my ride and couldn’t get it back up and working ever since. I have contacted support to help with this and no luck. I wonder if anyone here have experienced this and if there is any advice to resolve this problem.

    • Ian Russell

      This happened to my first 4iiii a few weeks in after working fine before – read crazy high or low for a few seconds then no reading at all. It was so soon after purchase that the distributor replaced it for me within a few days. The replacement has worked wonderfully for 7 months since…until the other day that is (see post 438 below)…

  128. I’ve had a 4iiii meter since June, and it’s worked flawlessly. I wanted to verify that it was consistent over temp, and sanity-check the absolute numbers, so I borrowed a PowerTap wheel for comparison.

    I stuck my 105 crank arm with 4iiii meter into the freezer, and then put it back on the bike. By the time I got it installed, synced the power meters, and rode for a minute, it was 50*F. At this temp I calibrated and rode at steady power – it matched the hub within a few watts (as viewed in Training Peaks after the fact).

    I then put a heat gun on the crank arm, and heated it to 120 degrees. I rode with the hot arm, without re-calibrating. Again, the temp had settled a bit – by the time I was done riding it was 102*F. There was no change; still within a few watts for the average of a 60s effort. I then re-calibrated and rode again – still no change.

    So, I’m happy with the temperature performance. I’ll still calibrate regularly, but I’ll no longer worry about spurious data on long rides that have big temp swings.

    This is a quick and dirty test, and I got average power by just selecting sections in Training Peaks. I’d say the error of my method is +/-5W, just in grabbing the data samples at the right point. It was off by as much as 5W between the meters. My power was 200W and 300W for my efforts, so I can really only say for certain that it’s +/-5% over a 50 deg swing (although it’s probably better – I tried to do this as accurately as I could). If you want to know if it meets the 1% spec over temp, you’ll have to do some proper scientific testing.

    Thursday I’ll ride on the road and see how it fares there, to get an idea of my L/R power split at different power outputs. But that data won’t do anyone else any good, of course.

    • Ian Russell

      Meant to say thanks for this info Philip, it’s really interesting to read and means I won’t be overly concerned should I forget to calibrate every so often.

  129. MARK HILL

    Anyone had the error 20 when calibrating 4iiii left power meter?

    • Ian Russell

      The error 20 (crank movement detected/bike not stationary) has just happened to me after 7 months without an issue. The power meter suddenly started reading nigh on 100W high towards the end of a recent ride (I know when I’m soft pedaling 200W on a climb these days and yet the reading was around 300W) and now won’t zero on either the phone app or the Garmin, it returns the error 20 code despite being stock still.

      I tried all the usual tricks, including changing the battery, and no joy so I suspect I will have to pursue a replacement from the distributor in the first instance or via 4iiii otherwise. Googling this specific problem suggests we’re not alone. It’s a shame because otherwise I’ve been super happy with it’s performance.
      Hopefully the customer service is good…

    • Tim

      I had this issue too, all summer long. (I was gonna send it in after the summer season.) Until this week when it suddenly started working for no reason. I’m not sure if I should hope that it stops working again soon so I can send it in…

    • Ian Russell

      How bizarre :/ Any idea what you did that might have prompted the “fix”or was it as random as the problem appearing?

    • Tim

      No idea what I might have done unfortunately. Which means that it could just as easily go back to not working randomly.

    • Ian Russell

      No worries, thanks anyway for the info, I hope it stays reliable for you! :)

    • Ian Russell

      Just a quick update to say 4iiii quickly verified that my unit needed replacing and issued a support ticket reference for my UK distributor, Hargroves Cycles, to replace under warranty. The service from Hargroves was outstanding and they turned around a perfectly working replacement within 2 working days! I love my 4iiii, despite the 2 hiccups I have experienced, and with after sales support as good as this it gives me confidence going forward, even if things go awry.

    • Roddy

      Did anyone find any solution about that error? I’ve been using it without any problem for the last 4 months indoors only but it decided to die today.

    • Tim

      Nope. Mine went back to not being able to zero offset. I sent it back to 4iiii, they removed the power meter from the crank arm and put another one on it and sent it back to me.

    • Peter Vanleeuwen

      I have had my power meter for 23 months. It just stopped working. Got the dreaded error 20. It happened to me one other time this year and I was able to get support and “reset” using the reverse battery trick. I found out that my cap had indeed snapped at the tabs like someone else mentioned. No idea how long that has been like that. After support sent me a new cap and the problem hasn’t gone away. I’m stuck with an over-priced cadence sensor. Funny enough I just bought a new bike and specifically bought a new crankset so that I could transfer my power meter. Support has offered me 20% off a new PM because I’m out of warranty. This error 20 seems super super common and I feel like 4iiii should be doing more. Needless to say, unless the tone of this support changes I will not be investing a significant amount of money into a product that will last for 2 years.

      ps.. I feel like PM companies should be offering longer warranties. 1 year? really? A power meter isn’t a consumable and they are “supposed” to be built with a decent level of robustness seeing as a bike gets pretty beaten up over it’s lifetime.

    • Iain Macleod

      I’ve managed to fix this “error 20” issue twice now (No thanks to 4iiii, their support is useless) using the fix this guy came up with. Follow the steps he details at the bottom and it basically factory restores the PM and everything works once again. Saved me a heap of money!

      link to docs.google.com

      Checked the readings were consistent afterwards against a tacx neo and they matched up quite well.

    • Tim


      For people still under warranty they replace the units, so you’d think that if this was a full fix for the issue then they would put this kind of factory restore as some kind of more easily accessible advanced option in their app, that would save them a lot of money. Perhaps it doesn’t fix it for every unit? Or it doesn’t fix the problem long term?

    • Iain Macleod

      Agree that whilst you’re still under warranty you may aswell get a new one as they don’t seem to have any issue replacing units. I was outside the warranty period myself which is what prompted me to delve deeper. When speaking with 4iiii to try resolve the issue I tried all their usual suggestions to no avail then got it to work using this. I emailed the details to them but never heard a peep back after.

      Can’t comment on whether it will fix every unit that has the error 20 message and long term all I can say is it’s happened twice in 4 months to me, usually when the battery runs super low, but I’ve fixed it both times nonetheless.

    • Ian Russell

      Thanks for all the info, changing my battery now as it’s hitting 20%!

  130. John

    Hey Guys-

    I just ordered the 105 version off CT. Haven’t been much talk of the newer updated ones. This review is from 2015, so any reviews or issues with the updated precision line? Are these generally OK? I figure for $359 with DCR discount, even if there are a few issues or left-only accuracy, it still will be great for a first power meter.

    • Ian Russell

      See the most recent DC roundup here under the 4iiii section: link to dcrainmaker.com

      Personally what I said above from my recent experiences: “I love my 4iiii, despite the 2 hiccups I have experienced, and with after sales support as good as this it gives me confidence going forward, even if things go awry.”

      I’ve been unfortunate enough to need two replacements but have received replacements promptly from my UK distributor after 4iiii confirmed warranty replacement was necessary swiftly – just had to be clear I had tried their standard troubleshooting routine to no avail. I have had complete confidence in my power numbers from the 4iiii when comparing to other sources of data and others power data. It has helped to dramatically improve my performance in the 9 months since I got it, despite riding just as semi seriously in the 3-4 years beforehand.

  131. Greg


    I was thinking about buying the Left only 4iiii precision to my ultegra 6800 crank, but according to their guide I’m very much affraid that it wont fit my frame :( On the picture it’s also visible that there is not enough clearance in the first 5-10 mm from the BB. Doeas it really need that whole space which is highylighted by grey on their fitting guide?

    Thanks :)

  132. Gerald

    I also got a deal on 360 EUR on the 105 versionsome weeks ago. I changed completely my training motivation, no issues to report!

    • Stephen Alderton

      I have just recived my 3rd 105 5800 crank arm the last one was working fine 10 months until I put a long ride in the other week. On the way back home about 2/3rds into the ride I noticed I was getting low power number readings then remembered I hadnt calbraed the unit before I set off so I stopped & tried to calibrate but got the erorr 20 failed to callabrate message. When I got home I changed the battery checked frameware etc but still got the erorr 20 message when I tried to callarate. I then contacted my UK distrobuter & they quickly sent out a replacement. Hopefully I have got a new generation one now & all the little hic ups are now sorted

  133. Conrad

    I just got a 4iiiis left side only and when using on Zwift my power is 20-25watts lower over my smart elite direto 100w on my direto is like 75 on left crank. I have re calibrated direto and zero offset the crank and nothing changed. It’s strange as when I pedal with the left foot only it seems to track closer. Maybe I’m really weak on my left leg. I have no idea what I can do as it feels really hard holding 170 Watts compared to the direto.

    • Chris S.

      In the 4iii app lets you set a scale factor for single sided use. Download the Precision Pro user manual and look at page 20.

    • Conrad

      Thanks i had a look and will try increasing the scale so it is close to the Direto, ordered a torque wrench also to make sure it is correct not sure that would make a diffrence. Dont mind a few % out but not 15% i doubt my leg discrepancy is that much out. i will have a play around and see.

  134. Sam

    I’ve had my 4iiii power meter for about a year and experienced no issues, other than it not connecting to the phone app to calibrate (happened around 5 times in 100 rides). I was about to purchase another one for my gravel bike, but reading some of the issues on here has me second guessing. I’m assuming there are lots of happy owners who are maybe the quiet majority. I can get a set of Favero Duo’s for 20% off which is tempting, but I like the simplicity of a crank based power meter and like my current pedals.
    It seems the price of the 4iiii is increasing. $750 in Australia for single sided is a downright ripoff when you consider I can get the Favero Duo’s (two sided) for under $1000 AUD. No way I will be buying another 4iiii until a good sale comes along!

  135. Sam

    Also why are companies persisting with the twisting mechanism to replace the battery. Surely this compromises the seal. If a battery only needs to be replaced every 100 hours, surely it would be more more watertight if the battery cap was screwed on with actual screws!

    • There’s an o-ring in there, so the seal maintains.

      Most consumers have voiced frustration with screw type battery compartments. It tends to be frustrating when you get a low battery warning before a long ride and have to spend 5 minutes futzing with getting a battery compartment open. Or the same if travelling and remembering a tiny screw.

      While obviously a screw-compartment tends to be more secure/waterproof, generally speaking most companies can do pretty well with o-rings and rotating tops.

    • Sam

      I take your point, but there also seems to be lots of frustration in regards to water ingress when it comes to crank based power meters. Personally I would sacrifice a little fiddling around in the knowledge that the compartment is more waterproof. It does seem that companies like Stages are getting better with their later generation units, which is a good thing.

    • Roger

      You can’t really say it’s an issue with crank based power meters – it was an issue with Stages only.

    • Sam

      Yeah fair enough Roger. As I said I own a 4iiii and have had zero issues. I always worry though when riding in the wet and when washing the bike down. I suppose I am being overly paranoid!

    • Roger

      Same here, I’ve had mine for a couple of years and never had an issue, but I also do keep the pressure washer pointed away from it just in case. My one single problem with the battery compartment is that it’s impossible to get the battery out without some sort of magnet. I’ve tried forcing it out with small screwdrivers but don’t want to push too hard and crack something.

    • This is clearly just an anecdote, but I’ve had a 4iiii meter for 3 seasons now, and show it no mercy. It sees rain, snow, mud, cobbles, gravel, and the pressure washer – sometimes all in the same day. I haven’t had any issues at all.

    • “My one single problem with the battery compartment is that it’s impossible to get the battery out without some sort of magnet. I’ve tried forcing it out with small screwdrivers but don’t want to push too hard and crack something.”

      Secret Battery Cap Pro Tip: Drop it. Seriously. Just take the battery cap with the battery stuck in it, and drop it on the ground. Or a table. It’ll almost always pop out. Sometimes it might take a drop or two. Works every time.

    • Roger

      hah, will try that next time

    • Javier

      Easier trick: use electrical tape. Adhere the electrical tape and gently pull, in one or two attempts it will exit.

    • Nathan B

      I’ve had my battery cap replaced twice by 4iiii where the thin tabs had broken off on the cap, and finally had the whole power unit replaced when the tab broke off in inside of the pm.

      I’ve been extremely impressed with the support each time, but the design does seem fundamentally flawed.

    • Sam

      So the main issue with crank based power meters revolves around battery cap issues. Either water ingress of broken battery tabs. I stand by my comment above! Use a cap and screws to secure the battery. Old fashioned I know but it would help to solve some of the major issues 4iiii and Stages seem to be having. Everyone has a screwdriver and it’s not hard to put a mini one in a saddle bag.
      I agree with the comment above from Peter in regards to warranty. One year is clearly not good enough. Even though I have had a great experience with my 4iiii power meter, I’m hesitant to buy another one due to the short warranty. I can get a set of dual sided Favero’s on special now for $200 more (AUD) than a 4iiii, which retails for $750 in Australia. The Favero’s also come with a 2 year warranty, which makes them much better value compared to 4iiii or Stages.

      The prices for single sided crank based power meters are crazy at the moment.

  136. Erik

    Does anyone know whether there is a way so that the unit will broadcast only cadence via BLE? I’ve got the PM on my bike that’s mounted on a wahoo trainer and have been using the trainer for power in zwift. I would to pair the 4iiii sensor for cadence only.

  137. ManuB

    Bought in july 2016. Dead in January 2019.

    Battery caps be dead and its impossible to saw that : send to precision : 200 dollars to repair because some water come inside ! (50% discount for the repair….).

    I dont recommand to buy this powermeter, not strong enough : lifetime #2 years.

  138. Haris

    from the look of it, it does not seem it would clear the chainstay of the more beefed up new BB90 frames (like the TREK Emonda for example). Any thoughts Ray?

    • Linda Stuurman

      I too would like to know this. Just got a Trek Emonda SLR with Dura Ace 9150di2 and there’s barely any space between the crank and chainstay … an AAA battery is about half a mm too fat. I’d really like to fit a very light PM on a very light bike :)

    • Jake Huggart

      Also came here hoping to find the same answer. The AAA only slides part of the way of the clearance guide on my Canyon Ultimate

  139. Manu

    Very good product. I use it for 2 years, works well, and very goods informations from the company. Buy it eyes closed

  140. lka

    Worked well for two years. After that ”the error 20”. Support useless. Disappointed.

  141. Phil Frost

    I got one of these installed by 4iiii on a Praxis Zayante Carbon, and it’s terrible.

    My first experience: the Android app offered to update the firmware, failed, and then would subsequently crash immediately as soon as it connected, rendering the app unusable. I was able to “fix” it by borrowing an iPhone and using that app to update the firmware to 3.2.0, which somehow is newer than the 3.0.0 that the Android app says is the “latest”.

    So the Android app is buggy, but also it’s terrible just as a power meter. I’ve tested it against my Kickr Snap and also against some hill climbs (link to strava.com).

    The reported power drifts by as much as 10%, perhaps due to temperature changes. And we’re not talking big changes like going from inside by a fireplace to freezing cold outside: we’re talking changes of 5-10 degrees. Power tends to go down as temperature goes up. My guess: the firmware performs temperature compensation based on the thermal properties of aluminium. Of course the thermal expansion of carbon is very different.

    Besides the drift, the numbers seem too far off to be realistic even immediately after a calibration. If I take the measured average power from a hill climb immediately after a calibration and compare it to the average power estimated by a climb calculator, the 4iiii’s numbers come out 26% too low. It’s hard to believe my L/R balance is so far off.

    I’ve contacted support, and they just make hand-wavy excuses. They tell me it’s difficult to compare numbers from climb calculators, apparently unaware of how physics works. (Incidentally, power2max suggests hill climbs as a way to check accuracy, and they say on their website if you do them and it’s significantly off they’ll take the unit back and inspect it. GCN has a video on it, too.) And they cast doubt on the Snap and say maybe the drift is due to tire temperature, etc. Which sure, could explain some variability but not anything near the magnitude I’m seeing.

    Given all the other reviews I guess not everyone has this issue. I don’t know, maybe it’s something about the carbon crank (which 4iiii says is compatible, by the way), or I got a bad unit, but since they really don’t seem to be eager to stand behind their product (and apparently, can’t develop an Android app) I’d definitely spend a few extra bucks for another brand if I had it to do again.

    • Miguel Serrano


      Do you have a contact in support, by any chance? I have tried to get someone on the phone or via email and they just will not respond – I sent a carbon FSA crank for a factory install just to be told 10 days later that the crank in not compatible – worst part is they have not returned the crank or even said if it has been shipped. It’s been almost a month.


  142. I just bought a 4iii left crank arm powermeter solution for a nice black friday price of 219€ Nov. 30th 2020. I choose the 105 Version, as the Ultegra was sold out and detected that the weight is the same: 105 arm incl. sensor: = 209 g / Ultegra arm without sensor: 200g!!
    Now i use it on a brandnew Wahoo Kickr V5 that comes with a +/-1% precision product promise and had to scale the power of the 4iii to 105% (using the Android App) in order to get almost same power results from both systems.
    The always asked question will stay: which system is moe accurate. To be honest: i trust in Wahoo more than in 4iii precision. Who has made similar experiences?? Ride On !! MAP

    • Good to hear it’s working out!

      One thing to remember though is that if you’re buying a left-only unit, you’re going to get quirks with left-only power. So that would likely explain at least a portion of your differences.

  143. Zhank you DC Rainmaker, for your comment. In addition to my latets post i did a ‘three powermeter’ comparison : Zwift Wahoo Kickr V5 Assioma Duo (pedal measurement on both sides) 4iii power meter (crank arm measurement left). The Assioma Duo show slightly too much compared to the V5. The 4iii crank arm power meter, however, shows a little less. The deviation of the 4iii can be explained quite easily – as DC Rainmaker already pointed out in his latest comment – with the one-sided measurement (left). In the diagram I have shown the Assioma cycling dynamics: I pedal 4% less on the left (48%) than on the right (52%). The 4iii crank arm power meter (one-sided measurement) doubles but the values ​​measured on the left single. If you only step to the left, the displayed power increases immediately. So if you only measure one-sidedly, you should know your personal ‘balance’ and if necessary balance the values in the power meter app using a preset. Best regards MAP

  144. Daffy

    Hoi ,
    Ik heb nu een 4iiii dubbel crank powermeter gemonteerd maar op ZWIFT kan ik de cadans niet vinden?
    Heeft nog iemand dat probleem ?

  145. luk

    what about R7000 105 right crank arm? is it hollow as well ?


    Just wanted to mention that I tried to order from your affiliate here. The showed the product in stock and went three weeks without an update. I canceled the order and ordered direct from 4iiii. Just thought you may want to know.
    Thanks for all your reviews/research.

  147. Jim

    Just some feedback on this power meter – its amazing value for a basic PM at just £250 at the moment here in the UK. My only complaint is battery life — I have logged every battery change and used veloviewer to see how many hours of active / moving time between battery changes. It’s a paltry 25-35 hours. In one case I only got 5 hours (cheap chinese battery). But even with Duracell (£2 per battery) I only got about 25 hours. When you cycle 300+ hours per year that starts to get expensive; probably at least £20 – 25 a year on batteries

    • Jim

      Update: In fairness the 25-35 hour battery life was between October and March winter months. Looking at my data for the summer months March to September I was getting 70 hours between battery changes; still only about half of the claimed 120 hour batter life from 4iii tho

    • Tim

      I looked at my last two battery changes, Oct 10 -> Jan 17. Just over 3 months. I usually ride at least one hour every day with a few rest days some weeks. The October riding would have been outdoors in temps between 0 C and 10 C. The rest would be indoors. I would guess between 65-90 hours riding on that one battery. Before that the batteries lasted 2.5, 2, and 2.5 months. Similar amount of riding, but temperatures would be different.

  148. Mark Schwettmann

    not sure if this is the right place to ask the question, but can anyone confirm what the “correct” behavior is for this meter (the precision pro) when paired via BLE?

    in the 4iiii app (which looks nothing like the screens in the manual, thx guys!) my left and right sensors appear on a single line, “paired” to each other. but to all bluetooth hosts, i still see two, a left and a right.

    i can connect to it, and i get a believable power reading and a balance value, but it would be nice to be sure that it’s not doing something wacky like doubling the power of one side but also sending the actual balance.

    this came about because i was trying to troubleshoot unreasonably low power values and discovered the two halves weren’t linked. i was getting the left power doubled – i think – which i verified by some hand crank turning and a reconfig in the 4iiii app.

    FWIW, it’s a factory install on a dura ace 9200 crank, which should hopefully not have the issues that the assymetrical 9100 cranks did. from what i can tell so far, my balance is off by quite a bit, 44/56 or so, especially as i get tired or out of the saddle, which isn’t terribly surprising but also explains why my numbers suddenly went to 13-15% less for the same effort, ride, and time when i tried to set this guy up.

  149. It’s been almost 6 years ago, but did it work?

    • Dick Pluim

      I was replying to another message so this now makes no sense. :-(

      Was a reply to someone who wanted to try it with Sora.(Reply #281)

    • JonP

      If it helps. I have it on a Sora crankset and it works like a charm – only bought and fitted in mid-2021 – went for the 105 crank, but fit and forget in about 20 mins. Eats batteries a bit, but better in summer as others have said. Very good value power option for those of us who need it for interest rather than specific intense training

  150. Erik Schumm

    I’ve had 4 separate 4iii power meters. 3 of them have had significant dropout issues. I sold the fourth before testing it enough to tell, which in hindsight seems to have been a bit of a dick move – I just assumed the replacement would work. I get dropouts at least once an hour where the power meter disconnects entirely. This varies based on the number of riders with radar and how much car traffic there is.

    – They have a big troubleshooting guide they will send you about bending the battery contacts out to help with dropouts, upgrading firmware etc.
    – They have problems with Garmin head units (I have tried a 530, 830 and 1000)
    – I get drop outs with a Wahoo Elmnt Bolt too. It is way less noticeable however because the wahoo will display the last known power until it reconnects. I am not convinced it is just a Garmin problem.
    – They have problems with radars
    – This includes those on passing cars (more and more common these days)
    – This also includes Garmin Varia (more and more common in group rides)
    – I currently have a quarq, 2 power2max and a stages power meter that does not have this problem
    – I have owned Favero and SRM in the past without this problem.
    I can get mine to behave most reliably riding solo without my varia and after having installed a .5mm piece of rubber behind the batteries in both pods. I still get occasional dropouts when a car comes by (my assumption is they have adaptive cruise control running)

    My recommendation: Buy something else than a 4iii.

    • Javier

      Totally disagree. At least 6 units of 4iiii (both single and dual ones) have been used for thousand of kilometers, not even 1 dropout. Not that Stages has a good reputation. Btw, used with Garmin 500, Garmin 510 and Garmin 830 without any issues or connectivity problems.

    • Mark

      yes, mine has worked perfectly as well. i ride with a varia and on plenty of roads shared with cars of all type, including self driving ones which presumably have all sorts of radar. never had a dropout once.

    • Erik Schumm

      Perhaps I have just had bad luck with the power meters.

      My comments about the radar and Garmin head units are from my correspondence with their support.

      I have had increasing dropouts with my specialized power cranks (which 4iii took support over for) and was told they were out of warranty. Paid them to do a fresh factory install, waited for them to replace the pods, and then had the exact same issues. Then I was told that they have issues with radar by support.

      I had two sets of mountain cranks from 4iii – one had dropouts and was warrantied. I ended up replacing my bike before I had a chance to ride the warrantied crankset for an extended period of time.

      At this point, I’ve asked for a refund and they’ve agreed. But there’s definitely an issue with connectivity. Some people blame Garmin. Some people blame 4iii’s. My experience is that 4iii is the common problem.

      here’s a couple results from garmin.com:

      link to forums.garmin.com

      link to forums.garmin.com