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4iiii Precision Pro Dual Left/Right Power Meter In-Depth Review

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While there are many power meter options being touted these days, it’s a different matter to actually get something shipped to consumers.  And to do something that’s accurate and trusted (as well as reliable).  It’s been a couple of years now since 4iiii started shipping power meters, and as of two summers ago when they shipped their left-only unit they’ve been quite a reliable as well as an inexpensive option.  Within that product, things have been accurate and I see very few complaints (almost none actually).

But that was on their single-leg system.  What would happen when they started shipping their dual left/right system?  Well, I set out to find out.  This past fall the company started shipping that to consumers, including a media loaner unit to myself.  Since then I’ve been testing and comparing it to a slew of other power meters on the market on daily rides.

With a system priced at $749 for a complete dual left/right offering installed on your existing crank arms, it’s one of the lower cost options on the market – so would it be accurate?  And is it reliable through the water-logged winter conditions? Let’s dig in.

Clarifying the options:

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Before we get too far along, it’s probably worthwhile to back up a bit (or a lot) and talk about how we got here, and exactly what this review is covering.  There are some nuances that are important to consider in this solution.

If we turn on the ‘way-back’ machine to September 2014, 4iiii launched at Interbike that year with what was planned to be a self-installable power meter.  You’d use some glue they provided, a bit of craftiness, and boom – inexpensive power meter on your existing crank arms.  While that may eventually be in the cards, the company switched directions after they said they had issues shipping said glue to consumers, due to shipping regulations around the glue itself (i.e. hazmat type stuff).

That led them to the scenario where you could send them your crank arm (left-only at the time), and they’d return it a short bit later with the power meter installed for you.  A few months later, they started offering the ability to buy pre-configured crank arms with the power meter already installed on it.  That not only got you a new Precision power meter, but also a new crank arm.  But this was all still left-arm only, and it was that product that I reviewed just over a year ago.

There’s nothing specifically wrong with left only, but it’s just restrictive in its ability to be accurate.  It’s only measuring one leg and doubling it (just like Stages does).  But as has been well demonstrated since then, your left/right balance varies not just day by day, but also often by intensity.  For example, I’m reasonably balanced up until my FTP, above which I become quite imbalanced.  Same goes for when I fatigue – which could be 1 hour or 4 hours into a ride, depending on intensity.

Of course, they were still working away on a right-only solution, that I previewed in the fall of 2015.  But it wasn’t until last spring at Sea Otter (2016), that they announced their specific dual plans.  This included details on their complete dual left/right setup, as well as upgrade options for those with left-only units that wanted to become left/right.

And that’s what this review is all about: The dual setup, with sensors on both the left and right arms.

So, just to recap what the basic 4iiii power meter product options/prices are:

Precision Pro Dual Sided installed on your crank arms: $749USD
Precision Pro Single Sided installed on your left crank arm: $399USD
Precision Pro Single Sided installed on your right crank arm: $599USD

Precision Single Sided (Left) including a new crank arm: $399USD to $599USD
Precision Dual Sided (Left/Right) including full new Dura Ace crankset: $1,499USD

Note that 4iiii lists all of their crank compatibilities on their site, though at this point their dual left/right compatibility list is a single line item: Shimano DuraAce FC-9000.

Got all that? Good.  Let’s get cookin’.

Unboxing:

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Of course, what’s in your box will vary based on what you bought.  In my case, it’s got the full Shimano Dura-Ace configuration for dual left/right. If you bought a left-only configuration, then you’ll want to see my previous review on the left-only solution.  Whereas if you buy the right-only version installed on your crank arms, then it’ll simply be lacking the left-arm sensor.

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In any event, here’s the box opened up:

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And then once I remove the parts from their cardboard friends, you’ve got this:

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All of which boils down to:

A) The drive side (right side) crank/arm
B) The non-drive side (left side) crank/arm
C) A plastic phone protector (consider it a gift)
D) A quick start guide
E) A small wrench for opening battery compartment
D) An extra two batteries (CR2032)

And the photographic version of that:

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On each side of the crankset you’ll see a 4iiii Precision sensor.  On the non-drive (left) side, it’s in the middle of the crank arm:

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Whereas on the drive (right) side, it’s located close towards the spindle.  The battery pod sticks through the spider, making it more easily accessible – but the sensor itself is actually on the right crank arm.

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Oh, and lastly – here’s a closer look at the extra battery, as well as phone inside the phone protector.  The protector is great if you ride in the rain with your phone in your jersey pocket.  Note that there is *NO* requirement for using the phone during a ride.  It’s purely for checking settings and such.

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With that all set, let’s move forward into getting it on the bike.

Installation/Configuration:

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Installation and configuration of any crank region power meter will vary heavily on which type of crankset you’re installing.  It’ll also vary on whether you bought the correct version for your bottom bracket and/or bike configuration.  If nothing else, spend your time doing your homework here.  Generally speaking, if you already have Shimano, then installation will be a breeze, since you’re replacing like with like. Whereas if you change brands/bottom bracket standards – then things get messy quick.

In my case, I was keeping like with like, so it was pretty straightforward.  I had an existing crankset on there from before, with the new one waiting below:

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To remove things, you’ll only need a simple hex wrench to loosen up the non-drive side bolt (on the left crank arm), which then allows you to then pull out the drive side crank arm – no tools required.

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Note that if your left crank arm has a small plastic cover over it (see this video), you’ll remove that by rotating it counter-clockwise.  Since you may not have the true ‘proper’ tool to do it, you can fake it with either a pair of pliers or scissors and then rotate using the slightly opened pliers/scissors to act as a tool.  Note: Not for cutting, just for grip.

Once that’s all done, simply screw in the left arm screws to the correct torque.  In general it’s best to alternate tightening each screw until snug.

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After that, simply attach your pedals like normal.

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And with that – you’re done.  Now, we will want to do a zero offset (aka calibration), but we’ll get to that in a second.

Finally, if the instructions above weren’t detailed enough for swappage of your specific crankset, I highly recommend YouTube to find instructions on being a bike mechanic.  If I’m not sure, I usually start there and go with more trusted bike focused sources like GCN, BikeRadar, Park Tools, and so on.

General Use Overview:

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In many ways, the 4iiii Precision power meter is like most other units on the market.  So if you’re an old hand at power meters, then honestly you’ll likely find very little new stuff in this section (though, the smartphone pieces is notable).  Still, I’ll run through them for the sake of completeness.  Plus, I just had mini-pizzas for lunch and have a spark of energy.

To begin, the 4iiii Precision transmits on both ANT+ & Bluetooth Smart concurrently.  This means that you can use any ANT+ capable or Bluetooth Smart capable device that supports power meters.  So on the ANT+ side that’s basically any Garmin cycling or triathlon focused device, as well as options from Stages (upcoming Dash head unit), Wahoo (ELEMNT), and even SRM’s latest head units like the PC8 (or trainer apps like Zwift and TrainerRoad).  Meanwhile, on the Bluetooth Smart you can connect via units from Polar and Suunto, but also smartphone apps like Strava and others .

I will note that Bluetooth Smart compatibility of dual left/right units does tend to be a bit more…fussy.  Companies continue to have a never-ending pissing match over standards here, and so things shift slightly from firmware to firmware and device to device.  But in general, people are reporting good compatibility results for the 4iiii dual units from what I’ve seen.  It’s the dual-piece that’s causing company’s issues since there are two connection points.

4iiii has a compatibility list linked off of this page, which lists the exact status of various head units.  For example, you’ll notice on their latest list that the Polar M450 is compatible, whereas the V650 isn’t.

In any event, starting off with the basics on the ANT+ side you can pair to it from any head unit by searching for a power meter:

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In the case of some head units, you can rename the sensor from the ANT+ ID to something more friendly, like ‘4iiii Precision’.  You can also check battery status this way.

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One of the most important things to do is regularly check your zero offset, which is a form of calibration.  Technically there are more detailed calibration levels, but for 98% of consumers out there, the zero offset is as close as they’ll get.  This allows you to monitor a given value and see if there are major changes to it.  Generally speaking, that number will shift with temperature, but in rare cases it can also change dramatically if something has gone wrong with the unit.  But, that’s not exactly how 4iiii works.

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Note that calibration should be done with the cranks in the 12/6 o’clock position.

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Now in earlier firmware versions, 4iiii with Precision would display the exact zero offset of both crank arms, alternating back and forth.  But now instead on the latest firmware, they display the status of each side, with a simple set of six possible values:

10 – Good, ready to ride

20 – Unstable data (bike not stationary)

30 – Low battery (less than 10%)

50 – Calibration error – contact support

99 – Power meter side not found

0 – Power meter not found

So basically: 1010 as seen above is ‘Good’ on both crank arms.

The positive side to this is that it’s far easier for most people to understand.  The downside is that it can make tracking calibration/drift variances harder.

Next, we can crack open the 4iiii app and look at Precision from there.  It’s here that you can start by creating a pairing between the left and right side.  This effectively allows either side to operate independently.  The option at the bottom allows you to unlink them.

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You’ll see that you’ve got battery level listed as well, here in slightly more detail than via the Garmin head unit.  You’ve also got a 3rd party apps compatibility option.  This goes back to my point of challenges with some apps over Bluetooth Smart. For example, Strava needs this setting configured when pairing with their smartphone app.  This is because some apps can’t handle the dual data streams from both units, and instead need a consolidated data stream.

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Like with your head unit you can also do a zero offset of the power meter from the app.  This is useful if your app (i.e. Zwift) doesn’t support sending a calibration value.  That way you can ensure your power meter is correct before starting.

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Shifting slightly to the hardware itself, we’ve covered that the pods are located on both the left and right crank arms.  You can see them more clearly on the left side when looking straight down on the unit, it’s the small pod:

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Whereas the right side, it’s hidden behind the crank spider a bit, but you’ll notice that vertical ‘bar’ (if you will) that connects to the crank arm.  That’s the right drive-side sensor.

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To change the battery on the left side, you’d simply open the little battery compartment up without any tools – quick and simple:

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Whereas on the right side you’ll need to use the included tiny hex wrench, to crack open that battery compartment.  Both sides use CR2032 coin cell batteries, which 4iiii states should get about 100 hours of riding time.

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Now one super-interesting and unique feature of the 4iiii Precision Pro dual system is that it can actually gracefully fail over from the battery dying on one side.  The unit is smart enough to detect a transmission failure on one side and automatically takeover doubling the remaining power side to continue giving you total power.  Basically at this point it acts like a one-legged power meter and doubles it, just as those do today.

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While hopefully you’ll have heeded the low-battery messages prior to that point, it’s a pretty cool feature that I’m not aware of being on any other dual power meters in the market today (some can keep transmitting if the secondary/slave side fails, but none that I know of can dynamically switch between *either* crank arm if *either* crank arm fails).

Finally, when out on the road the unit will be broadcasting the following specs:

ANT+ Power (total)
ANT+ Power Balance (left/right)
ANT+ Cadence
ANT+ Pedal Smoothness
ANT+ Torque Effectiveness
Bluetooth Smart Power
Bluetooth Smart Power Balance
Bluetooth Smart Cadence

You can see this detail on the head unit itself of course, or afterwards on various platforms depending on the capabilities of the platform.  For example using the baseline of Garmin Connect, here’s what you’ve got for a ride.  Whereas if you pair to Suunto’s platform you won’t get some of the additional power meter metrics beyond baseline power, since Suunto doesn’t support those.  Meanwhile, Polar sits somewhere in the middle on support of advanced metrics.

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With all of the operational use things out of the way, let’s dive into the accuracy pieces.

Power Meter Accuracy Results:

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I’ve long said that if your power meter isn’t accurate, then there’s no point in spending money on one.  Strava can give you estimated power that’s ‘close enough’ for free, so if you’re gonna spend money on something it shouldn’t be a random number generator.  Yet there are certain scenarios/products where a power meter may be less accurate than others, or perhaps it’s got known edge cases that don’t work.  Neither product type is bad – but you just need to know what those use/edge cases are and whether it fits your budget or requirements.

But this isn’t that type of product.  4iiii Precision is designed to compete with the best power meters on the market, and designed to be used by the best athletes in the world.  After all, 4iiii sponsors not just one – but two UCI World Tour Pro Teams this year; these are teams that will ultimately compete for the podium in the Tour de France.  So the question is: Is it actually accurate?

Well as always I set out to find that out.  In power meters today one of the biggest challenges is outdoor conditions.  Generally speaking, indoor conditions are pretty easy to handle, but I still start there nonetheless.  It allows me to dig into areas like low and high cadence, as well as just how clean numbers are at steady-state power outputs.  Whereas outdoors allows me to look into water ingest concerns, temperature and humidity variations, and the all important road surface aspects (i.e. vibrations).

In my testing, I generally use between 2-4 other power meters on the bike at once.  I find this is the best way to validate power meters in real-world conditions.  In the case of most of these tests I was using the following other units:

PowerTap G3 hub based power meter
WatTeam Gen2 power meter
Tacx NEO Trainer
CycleOps Hammer Trainer

In general, my use of other products is most often tied to other things I’m testing.  In this case I was testing both the WatTeam and 4iiii’s units more or less concurrently.  The 4iiii started off earlier in the season (mid-fall), and then the WatTeam was added in December.  Also, when it comes to data collection I use a blend of the NPE WASP data collection devices, and a fleet of Garmin head units (mostly Edge 520/820/1000 units).

Note all of the data can be found in the links next to each review.  Also, at the end is a short table with the data used in this review.  I’ll likely add in other data not in this review as well once I finish consolidating that data.  I’m a bit behind on getting data off some of my head units into folders.

With that, let’s get started with an indoor test (data here).  This one was on the CycleOps Hammer with TrainerRoad controlling it.  Note that this was done prior to a Hammer firmware update that addressed some of the spikiness, so don’t mind that too much on the Hammer.  Here’s the overall ride, which was 30×30’s (30 seconds hard, 30 seconds easy).

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Now at this level things look good, but let’s add a bit of smoothing (10 seconds) to it and zoom in on some of the intervals.

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In this case, things look really damn nice.  All units are within a max spread of 10w of each other at 420w at the peaks.  Slight variations are of course totally normal given placement and data collection differences.  10w on 420w is a max difference of 2.3% between the three units, well within the limits when you talk overlapping accuracy rates of 2% (thus a total of 4%).  So all good.

Now total power is great (and super important), but since we are actually buying a left/right power meter, what about the left/right pieces?  My analysis tool can actually split those apart and show them individually. In this case, only two of the units on this ride were capable of doing left/right splits (my PowerTap P1 pedals weren’t on this bike unfortunately).

What you can see here is the upper portion of each work interval shows the right side, while the lower portion shows the left sides.  And nicely, they align within 3w of each other.  Sweet!  You notice a slight dip in difference though on the rest portion below on one interval on the left pedal.  It’s not clear to me why there’s a difference when at about 50w between the WatTeam and 4iiii Precision units though.

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So, all seems generally good though on that ERG mode structured workout.  Let’s shift to another indoor workout though, this time over on Zwift.  This workout was just in normal Zwift wandering mode, where I had the freedom to throw down power as I saw fit.  For the most part I rode relatively steady-state, but you’ll see some sprints in here.  Here’s the high-level overview, smoothed at 5-seconds:

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Overall things look pretty good. You see a few drops towards the end that appear to be ANT+ drops (tell-tale sign being complete drop-out of data), mostly impacting the trainer, which was furthest from the ANT+ stick on the laptop.  Focusing on the power here, I’m interested in looking at some of the sprints, so let’s do that and zoom in on the one in the middle around the 35-minute marker.  First, let’s remove smoothing altogether:

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What you see here is the recording interval of once per second, and the changes happening within that.  What you see above (as blocky as it is), is 100% normal.  Due to differences in update rates (sub-1-second) and recording rates, you’ll see slight variations like this.  Still – two of the units actually hit the same max wattage of ~700w (+/-3w) within 1 second of each other.  Depending on where I drag my mouse over the line, it’ll show that.  The WatTeam never quite gets that close, coming in about 30w lower on this particular sprint.  On other sprints it was closer.  Here’s the smoothed view at 3s smoothing:

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As you can see, the Hammer and 4iiii match near perfectly (there is a slight offset of one second, which could be just due to one unit being one second faster on time of day, or could be due to simply recording delay – hard to know exactly).  There’s also the element that in theory, the Hammer should be maybe 1-3% lower in wattage than the 4iiii unit, due to placement and drive-train loses – but again, that’d fall into the +/- 2% tolerances overlapping giving a total range of 4% between then.

Let’s shift outdoors a bit and on a longer/colder/wetter ride out into the countryside.  Here’s the overview at 15s smoothing:

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Overall things look pretty close between the units, minus a few oddities later on with the WatTeam unit on a section of larger cobblestones at high speeds (other portions of the ride on smaller cobblestones were fine).  But otherwise, all is mostly well.

Let’s again look at the sprint there around the 46-minute marker, zooming in at a smoothing of 3s:

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We can see all three units react pretty quickly to the sprint event, which they show topping out at 818w (PowerTap G3), 800w (4iiii Precision), and 751w (WatTeam).  However, if I reduce smoothing to 0 seconds, then you see slightly different results – again mostly owing to variances in recording/transmission rates.

Here (if I move my mouse over the three-second period) we see the 4iiii Precision top out at 841w, 828w for the PowerTap G3, and 768w for the WatTeam G3.  It’s virtually impossible to say which one is most right (though I’d argue that the WatTeam is likely least right in this sprint).

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Finally, for this ride, we’ll take a roll down the famed Champs-Élysées– filled with cobbles that cause plenty of power meters issues.

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Mid-day it’s a bit stop and go on that route, but that’s interesting anyway because it shows how quickly things react.

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Above you can see that the G3 and 4iiii generally match pretty well across the board, though the WatTeam was often a little bit lower on this type of stop and go on cobbles aspect.

The stop and go is also interesting because it allows me to take a look at the cadence data.  Below you can see the WatTeam and 4iiii units match nearly spot-on, whereas the G3 with it’s estimated cadence struggles a bit on the stop and go aspects, which is common for it.image

Okey doke – so overall I’m just not seeing any issues with the 4iiii Precision unit from an accuracy standpoint.  It’s matching other power meters on a wide variety of conditions and environmental scenarios.  And numerous other tests I’ve done match these results as well as being very stable and clean from a data standpoint, both for power and accuracy data.

Here’s a small table of data covering the 4iiii Precision Dual unit. As noted, I’ve gotta dig up a smattering more data files off some head units and add them into the charts.  But in the meantime, feel free to dig through this data.

4iiii Precision Data Sets

Workout TypeDCR Analyzer LinkProducts Used In Test
IndoorsAnalyze4iiii Precision Dual, WatTeam Gen2, CycleOps Hammer, TrainerRoad Control
IndoorsAnalyze4iiii Precision Dual, WatTeam Gen2, CycleOps Hammer, Zwift
IndoorsAnalyze4iiii Precision Dual, WatTeam Gen2, CycleOps Hammer, Zwift
OutdoorsAnalyze4iiii Precision Dual, WatTeam Gen2, PowerTap G3 Hub
OutdoorsAnalyze4iiii Precision Dual, WatTeam Gen2, PowerTap G3 Hub

Note that the above data is charted/plotted using the DCR Analyzer tool, which is designed specifically for comparison of sensor data such as power meters.  You can read more about it here, as well as leverage it for your own tests.

Power Meter Recommendations:

With so many power meters on the market, your choices have expanded greatly in the last few years.  So great in fact that I’ve written up an entire post dedicated to power meter selection: The Annual Power Meters Guide.

The guide covers every model of power meter on the market (and upcoming) and gives you recommendations for whether a given unit is appropriate for you.  There is no ‘best’ power meter.  There’s simply the most appropriate power meter for your situation.  If you have only one type of bike I’d recommend one power meter versus another.  Or if you have different needs for swapping bikes I’d recommend one unit versus another.  Or if you have a specific budget or crankset compatibility, it’d influence the answers.

Now since the guide came out this past fall, there really hasn’t been any major entrants in the market that weren’t already covered in that post.  However, there have been two noteworthy changes:

A) 4iiii Precision Dual Review (this post, obviously): The post in my annual power meter guide didn’t cover the accuracy aspects of the left/right setup, so I didn’t dive into general recommendations.  But given the data I’m seeing here – I think it’s safe to say I have no issues with recommending this as a dual left/right setup.

B) WatTeam Gen2 Dual: This unit’s review is coming up in the next few days.  Though it was on the same bike as the 4iiii Precision unit, so if you simply look at the data above, you can get a feel for at least the accuracy portion of things.  That’s a cheaper self-install solution at $499USD (dual).

Oh, and technically, there has been a third entrant – a company called Arofly – introduced a small accessory ‘power meter’.  I’ve got one that arrived today in the US at my forwarding box (finally!), and I’ll be shipping it over in the next week or so.  It’s priced very cheap, but I’m extremely hesitant to say it’ll be accurate until I’ve tested it.  There’s a lot of questionable claims made on their site, starting with fabrications about their pro athletes and coaches and credentials (they aren’t pro, and they don’t exist).  As such, where there’s smoke…there’s fire. Still, perhaps the tech will be better than their truth-telling skills.

Summary:

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It appears that 4iiii has managed to make good on their long-promised plan to get a dual left/right power meter into people’s hands on their own hardware in the $750 range.  And they’ve done so with a dependable and accurate product that I’d be happy to use day in and day out.  It’s sleek and barely noticeable once installed on your bike, compared to other lower priced dual options like WatTeam or BePro.  Of course, both of those companies have other benefits around portability between bikes not seen in the 4iiii solution.

Of course, there are some downsides to the 4iiii Precision Pro dual solution, most namely crankset compatibility.  Right now it’s only offered on a single crankset, in large part due to the challenges of fitting a sensor in/behind the drive side.  Which to be fair, is pretty common for dual systems that aren’t pedal based.  Meaning that if you look at other dual (ROTOR & Verve) solutions they’re extremely limited as well in compatibility.  As each needs to be ‘fit’ to the unique requirements of a given drive-side crankset.  Whereas with pedal based solutions (i.e. Garmin Vector, PowerTap P1, BePro, Look, etc…), they have far more flexibility since they don’t have to ‘deal with’ anything near the spider of the crank.

Hopefully, in time 4iiii will be able to get more dual model offerings out there for their dual setup.  Though given that Shimano dominates the crankset market, they’ve clearly focused on the widest possible market penetration point.  And from a business standpoint that certainly makes sense.  In the meantime though, if you’re on a Shimano crankset, then this is without question one of the least expensive ways to get accurate power for dual legs.

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 Clever Training to offer all DC Rainmaker readers an exclusive 10% discount across the board on all products (except clearance items).  You can pick up the 4iiii Precision from Clever Training. Then receive 10% off of everything in your cart by adding code DCR10BTF at checkout.  By doing so, you not only support the site (and all the work I do here) – but you also get a sweet discount. And, since this item is more than $49, you get free US shipping as well.

4iiii Precision Power Meter

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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91 Comments

  1. Eric F

    Thx for the review. Good to know that the dual version is precise :)

    Hopefully they will eventually start doing right side installations on Ultegra cranks.

  2. Patrick

    Looks like a great product. Any idea if they plan to ever offer “send in your own cranks” dual-sided for Ultegra 6800?

    • Roy

      I emailed this question to 4iii back in late December and they replied “The Ultegra dual is on our roadmap but we don’t have a scheduled release date yet.”

    • Eric F

      In other news, 4iiii releases power meter for indoor cycling…

      link to 4iiii.com

      Think they’re still working on Ultegra right side power meter? Still hoping that this will happen in time for 2017 season (Northern hemisphere). Otherwise, those P1 pedals are quite tempting.

  3. JAVIER

    I have the single side 4iii precision powermeter in shimano 6800 crankset. Any idea when (if) it would be avalaible to add the powermeter to the right crank? And, it would be done in Europe too (without sending it to Canada, which increases the price for the custom fees quite a lot). Thanks.

  4. Erik

    I just tooked a look at Arofly’s hi-tech, world-changing super website. I think you will find bestest value and quality of fitness results with amazing product. I look ever forward to your biker review of product.

    Also, I have a Western Union money order from Nigeria waiting for you to claim for $1,000,000,000. I just need a small deposit to clear customs…

    Good luck, I hope that thing doesn’t kill you.

  5. Brian E.

    Thanks for another great review! How much weight did the power meter add? This one is now definitely on my short list. Will you be doing an in depth review of Rotor 2INPower power meter? I would love to see how they compare (especially since Rotor also offers an “aero” version. I guess the downside of being so good at what you do is that you get pestered about when the next review is coming out!

    • Fabio

      I remember he mentioned the 2INPower review was coming after 4iii. I do own one and I’m happy with it, never had an issue but I’m curious to get his point of view.
      Cheers,
      Fabio

  6. Cornelius Carroll

    Has 4iiii mentioned any future plans for crank compatibility? I’d love to put this on something like an Ultegra or 105 crank.

  7. Jimmy Stevenson

    Thanks for the great review, and especially for the compatibility charts.

    I have been leaning toward buying a 4iiii power meter for a few months now. This review has finally sold me. Now the question is left only or dual. I’d have to do a full crank upgrade to get the dual side. So, time to make some decisions.

  8. Greg

    Has 4iii shared any recent information about progress toward a version for carbon cranks?

  9. TM

    pretty sure my wife is going to try to find out a way to block your website in an attempt to get me to stop spending money…

  10. Brett

    Ray, thanks for the review… always good stuff!

    Couple of off-topic questions:
    1) what is the bike stand you are using in the outdoor pics? Link?
    2) I did not see your usual disclaimer about sending back freebies/loaners and buying your own. Oversight or did something change?

    • Hi Brett-

      1) Here’s the stand I use: link to amzn.to (it looks to be identical to what I have, just branded, I found mine from a European retailer). I use it all the time for shots, and have a small stash of them.

      2) Same as always, I send back. I tried using the term ‘media loaner’ within the intro paragraph this time to minimize text bloat, but perhaps I should go back to the normal wording. Either way, will shortly go back to them. I’m using that bike for the ROTOR power meter, so it’ll get down down this week and re-built. I’m just waiting to confirm if WatTeam has any final firmware updates that may cover a few of the smaller issues I saw with their data in December (as seen in this post in fact). So if there’s something that addresses things, then I’ll probably hold off a week or so in sending everything back since it’s attached as one big set.

      Cheers.

  11. Rhys

    Been looking at these since first announced. Reading this review convinced me to buy them. The £140 shipping charge put me off.

  12. Thanks again for another great review.

    Any idea if there will ever be a shimano 105 level powermeter ?

  13. Iain Gray

    Ha. I have 2 left side 4iiii power meters and was waiting for the dual review. Gave up waiting and put up my cash last week. Glad the DCR’s review backed up my experiences of the left side.

  14. A M

    My choices are limited when it comes to a trek bike specially if I wanted a dual sided power (sick of stages v1).. Torn apart between pioneer and shimano R9100P and to complicate matters more I don’t want to let go of my Edge 1000 just for the pioneer pedal metrics. Checking your blog almost daily for an updated review about pioneer and R9100P, appreciate your work!

    • I wouldn’t expect a review of the R9100P anytime soon. I haven’t seen anything that indicates sooner than spring (at best) availability. Once I have a unit, it’d be 30-60 days or so from that point. I’ll definitely note once I have a unit though.

      On the Pioneer, you’ll find my review here: link to dcrainmaker.com

      While they’ve expanded cranks and such, nothing has really change at the core technology level, it continues to work really well for folks.

    • A M

      Appreciate your response Ray,

      The pioneer system sounds promising with their head unit.. but I really believe that Garmin will allow Shimano to show pedal metrics considering how gigantic Shimano is. Probably the most logical thing to do is wait till R9100-P is released since my stages is still functioning.

    • Honestly, zero chance of that happening anytime soon. Here’s why:

      A) In order for Garmin to even consider adding it to their head unit at this point, there would have to be a standard for that data. At present, there isn’t an ANT+ standard for it. While it’s been discussed for years, it just hasn’t happened (in large part because Garmin refuses to make their variant a standard).

      B) Even if it was announced tomorrow that a standard would come out of nowhere (and I’ve heard nothing to indicate that’s being worked on), it would be at a minimum almost a year till we saw it formalized. Again, using past indicators as a guide.

      C) All of which ignores the fact that Garmin would see the R9100-P as competitive, so no reason to make it any easier for them.

      D) Inversely, I don’t think the R9100-P will sell that well anytime soon, because I haven’t seen anything indicate it’s price competitive.

      Again, just my two cents.

  15. Ivan

    What about the frame compatibility? I think this is the most important limitation

  16. Mario Simas

    Can I buy this in Europe?

  17. Andre

    Thanks for the great review (as always).

    A dual-sided version for the Cannondale SiSl2 Hollowgram crankset would be the most bad-ass powermeter in the world and a weight weenie dream comes true… maybe if 4iiii partners with Cannondale like they did with Praxis…

  18. Jason

    Any idea what the turnaround time is if you send 4iiii your crank to get the dual sided PM installed? I’m in Canada so I guess that might speed things up a little, not having to worry about customs and all.

  19. RayG

    Can you change chain ring sizes? That right side pod looks like a narrow fit in the gap between crank and chain ring.

    I ask because I’d occasionally like to run 50/34 when I’m doing long mountainous rides.

  20. Markus

    Any word on a MTB version? In September 2016 4iiii announced a dual side MTB version, release date October 2016. However, haven’t seen anything since then.

    link to 4iiii.com

  21. Wim

    Great review. Living in germany i have been in contact with them to check the possibilities to send my crankset to Canada. In that case you need to pay VAT and duties which does make it any longer a cheap solution. Besides this there is no support in Europe which means that every time you have an issue you can ship everything back to Canada

  22. Mickey

    Hi Ray,
    You mention in this review that the units are smart enough to switch to single sided mode in case of battery failure in the other pod. Does this mean I can basically split up the left crank arm from the right side and use the separate halves on different bikes? This is actually a major upside for me as I have a handful of bikes with compatible shimano cranksets and currently I’m swapping a left-side stages crankarm between bikes. It would also be interesting to compare onesided power between stages and 4iiii.

    • Mickey

      Also any chance of getting the 10% clever training discount for the self install :D?

    • Yes, with the unlink option you could/should be able to do so. I haven’t tried it, though it might be interesting to see how it works if I even just ‘pretended’ they were on separate bikes (i.e. by either taking one half of the battery out of each one, one at a time, or seeing how the unlink option worked concurrently).

      As for the 10% CT discount, it does work on the 4iiii products, though at this time they haven’t made the dual setup available to Clever Training yet. My understanding is the two companies are discussing it, but I pretty much leave that in their camps to deal with.

  23. ekutter

    What are the actual weights of the single sided and double side options? The specs on the 4iii’s web site are kind of vague. 9 grams for left only, 25 grams for right. Is the 9 grams for left only actually accurate, with or without battery? Is the 25g the total for left/right or is it just the addition for right, on top of the 9 for the left? Worst case is still crazy light. But curious what the real numbers are. I’m leaning towards the left only which is a really light option to get cadence and reasonable power.

    • Those 9g/25g sound correct. My understanding is that it’s with battery. Having held the pod unattached to a unit before, it’s basically like a footpod without some of the extra bulk. It’s virtually nothing.

  24. A M

    Can someone give me recommendations/ideas on post #20?

  25. Batholith

    I can’t see this competing as a pre-install against the upcoming Dura Ace. For those of us who’d be hit by import taxes, sending the crankset/crank arms in is a nonstarter.

    • I think the challenge will be that Shimano still has to prove accuracy. They have built a good team to do so, but so have many companies before them. Money doesn’t equal accuracy, it took Garmin three years from announcement to shipping to sort that out.

  26. matt

    just want to reiterate to people its not just as simple as having dura-ace cranks and this option will be good for you. My BMC has asymetrical chainstays and there is not enough clearance between the chainstay and crank to fit the precision. Would of loved it to be the one for me after already failing with watteam and powertap p1’s. Now expecting a second batch of delays on already ordered power2max ng units….grrrr!!

  27. Howard

    Hi Ray, would you recommend left-only 4iiii Precision over WatTeam Gen2? I am a beginner and is looking for a power meter to help me better train with Zwift and TrainerRoad. Your input is highly appreciated. Thanks.

    Howard

    • That’s tough. On one hand, I’m not a huge fan of left-only solutions as I think they aren’t as repeatable as people think they are.

      On the other hand, while WatTeam Gen2 is a dual system, you can see the outline of some issues I noted in this post around measuring high in sprints, and some minor issues in larger cobblestones.

    • Howard

      Hi Ray, thanks for reply. I remember that you said consistency is more important than accuracy. I am aware that my imbalance will make the reading over/under if I go for left-only. Or would you suggest BePro? I will have to change pedals cause I am now using SpeedPlay.

    • Accuracy is more important than consistency, only because if you have accuracy – you don’t have to worry about consistency*. ;)

      The challenge with left/right imbalance is that it may not be consistent – so it could be all over the map. I think BePro may be your best option at the lowest price point.

      *Note/Nitpickers Corner: There’s a famous picture of accuracy vs consistency on a dart board. The problem is that it’s not super great because in this case accuracy is always defined as a percentage related to the true value.

  28. Artur

    Hi Ray,

    You’ve mentioned already lack of comparison to P1. Would much appreciate if you could add that data comparison also at some point.

    Thanks!

    • I don’t believe I did any P1 comparison data during this round of testing, as I had those pedals on another bike for the whole time. The other data I have is mostly trainer/PowerTap G3 based.

      Or do you mean something else?

    • Artur

      Hi Ray,

      Thanks for getting back. I was just curious to know if you planned to go back to compare to P1 as well. Given (I believe from reading your web site for a while) P1 and G3 correlate well with each other, one should not expect a major differences between 4iiii and P1 as well?

      Thanks!

    • I would expect virtually no difference between the P1 and 4iiii.

      Perhaps down the road I will, but at the moment I’ll be removing this power meter set (inclusive of the WatTeam unit attached to it), to make room for the ROTOR power meter that’s been waiting in the queue for testing.

  29. Am I the only person who finds it weird that they seem to be going after the value oriented consumer with being the low cost entry but go with dura ace at the beginning and not 105? At 1499 thats the same price as pioneer prebuilt or ~$1050 if you buy separately. Yes that includes with cranks but wouldn’t those trying to go for value with a power meter also go for value on cranks where 105/ultegra/dura ace aren’t that different so wouldn’t have dura ace on their bike?

    105 cranks are ~$100, ultregra ~$150, dura ace ~$300 from what I can find.

    • True, though, I think in some ways by going with the high-end they set the expectation that they are just as accurate (and there’s nothing that I’ve seen that says they aren’t).

    • davie

      In my local ride group and club, the vast majority of folks use shimano cranksets in Ultegra 10 and 11 speed with a few dura ace 9000 and 105 5800. They all run edge 500’s, 510, of 520 head units.

      Most of these people would love a reasonably priced shimano compatible power meter but we are stuck between massive expense (SRM), compatability nightmares (Quarq bottom brackets, etc), difficulty with post purchase upgrades (pioneer upgrades only via head unit). Stages is left only with no plans to ever go dual.

      There is a massive hole in the amateur market. Surely 4iii must know this.

      Their left sides are already selling well and upgradeable to dual. If they release a dual for ultegra or 105, right side/dual, they will make pots of cash.

    • Michael Swann

      I’d consider upgrading my Precision to Dual if 4iiii released a 105 version. The Precision Pro in Ultegra costs as much as my bike did when I bought it, so having a power meter that costs as much as my bike probably isn’t going to happen.

    • Michael Swann

      Oops. I meant Dura Ace, not Ultegra. It’s only available in Dura Ace.

  30. I can’t wait for the Arofly review….I could use a good laugh

  31. Daniel Boni

    i was pumped about the powerbeat gen2 but not so pumped anymore after seeing that crappy power output

  32. Tim B

    Thanks for the review. I’ve been waiting on the development of the 4iiii dual as an upgrade to my current unit.

  33. Michael

    Would it be possible to use just the right side as a right-only power meter or could there be any problems since that would not be the intended use? I use 4iiii Precision left-only power meters on all my road bikes except one, because there is not enough frame clearance at the left chainstay. I am now considering my options for said bike and would be perfectly happy with a right-only variant.

  34. Mark

    Hi Ray,

    any idea why the 4iiii power meters are not available on the Clevertraining UK website?

    If they were I take it the 10% discount would still be applicable? Trying to work out a cost effective route to purchase in the UK.

    Thanks

    • They’re working on it, but no specific timetable. Generally speaking retailers are negotiated on a per country level, so it’s a bit of a slow process.

      The 10% discount is applicable no matter the locale.

    • murray

      Mark,

      i just bought a 4iiii left only 105 5800 on hargroves cycles, entered ’30pound’ discount code and got 30 off,

      £349 with free delivery, not bad!

  35. Johannes

    How do you find it handles cadence and power balance?

    My first dual sided Precision Pro had issues with both, and 4iiii therefore had me send it back for a replacement. I have just received said replacement, but sadly the same issues are present on this one as well.

    It still can’t measure cadence below 30 (while specifications at least at one time stated it should be accurate down to 10), and when below 30 cadence (say 25), power numbers show zero the large majority of the time, which of course skews power numbers (when doing a low key cool-down, for example).

    Regarding left/right power balance, neither of my two Precision Pro’s have been able to accurately handle single leg drills.

    When pedaling only on the right side, the balance shows as 1%-99%. It’s not as bad on the left side, as it mostly shows the correct 100%-0%, while occasionally shifting to 99%-1% for a short while.

    I’m would guess these mismeasurements are affecting power accuracy in some way, but disregarding scenarios below 30 cadence, the power luckily appears to be closer to my Tacx Neo and Power2Max than my first Precision (which read about 3% lower than both), which is at least something, although I find it all a bit disconcerting.

    • No issues with cadence/power balance for me.

      On cadence, I typically test down to about 32, since that’s (or 19) usually where most other power meters drop-out. Still, what specific drills are you doing below 30 that you need that for? Just curious.

      On 99%/1% power, there’s actually some interesting debate within the industry on it for single-leg pedaling. But most power meter companies roughly agree that 99%/1% is likely correct. The reason is that the other pedal is still flopping around, and as you get that moving, it’s likely to exert some torque onto the crank arm. How much will likely vary based on speed and stability. I suspect the differences you see there might be due to your leg strength/stability on one side or other. Just my guess.

    • Johannes

      Thanks, Ray. That’s reassuring that it’s apparently normal behaviour for these types of power meters.

      I first noticed the power dropping out below 30 cadence, while tiredly spinning the legs after a Zwift race and comparing power between the Tacx Neo and the Precision, so no specific drills involved.

      There was of course a significant difference in average power for the duration of my cool down, because Precision measured zero for such a large portion of the time, while the Neo measured correctly.

      This had me worried, as I had never noticed this on my Power2max, which seems to be able to correctly measure power at a lower cadence than the Precision.

      Knowing that it’s normal behaviour for both the Precision and similar power meters, I’m worried no more, though I prefer power meters that are able to measure power at a lower cadence than 30, just to be able to get as much correct data as possible for as wide a range of riding situations as possible.

      I would imagine cutting to zero earlier than other power meters when you stop pedaling or simply spin very slowly for a short while when otherwise riding normally (during a race to rest the legs a bit, for example) would affect average power for a ride or a section of a ride somewhat as well.

      That doesn’t seem to be the case for me to any measureable degree beyond the error margins, but I would guess this possible downward skewing of the numbers would depend very much on individual riding style and the specific circumstances of the ride.

  36. I would be interested in the Dura Ace 9100 dual side version of the 4iii power meter. Let’s see when the professional 4iiii sponsored teams make the switch to the new group-set.

    Very interesting power meter due to the competitive price-point at a reliable quality.

  37. Looks like 4iiii is sold out for dual leg

  38. Klaus

    I’d be so interested in an Ultegra version of this, price point seems to be right if one already has a crank and arm.

  39. Christina

    Hi Ray, I appreciate all the work you do to get unbiased information out to athletes. If I’m looking for something new, this is the first place I look. Today I learned about power meters (so am a total newbie), and am interested in the 4iiii. You indicate that it works easily with Garmin devices. Does this include wearables (I have a Fenix 3 sapphire), or just their Edge series?
    Thanks!

  40. Neo Zhao

    Quick tip about torque effectiveness and pedal smoothness metrics:
    According to 4iiii, “These features were available for early adopters until January 16, 2016 and are no longer included with the firmware. However, as a good will gesture to you I can enable these features.”
    I bought my left 4iiii crank last year. It came with these features enabled. After upgrading to dual sided Precision, I lost both. So I send my ANT+ ID and series number of both left and right to support@4iiii.com to have these enabled.
    Just a heads up for those who are wondering.
    Maybe they just enabled these features for Ray’s test unit.
    Don’t really get the point of this policy…

  41. Matt

    Hallo ray

    Do you know when the precision pro is available in Europe? And can i combine the pm with osymetric chainrings.
    Cause some powermeters “don’t like” osymetric.
    Thanks Matt

  42. Howard

    4iiii just send me a facebook message saying that Cannondale SiSL2 will not be compatible with the Precision Pro.

  43. Alan Hogan

    Since there isn’t a specific review yet by Ray Maker on the 2018 Specialized crank power meter but it does appear that 4iiii are working with them. Does anyone know a release date set for the power meter? Couldn’t find anything. Ray Maker any news?

    • If/when Specialized announces a new tech product, I’ll likely have a review for it.

    • Vladimir Trofimov

      Hi, Ray. I have dual 4iiii. I don’t see ANT+ Pedal Smoothness
      ANT+ Torque Effectiveness , but I see balance. Why and what I must be doing for it. I have garmin 820. Thanks

    • Johannes

      Back in March I got the following reply from 4iiii support regarding these metrics:

      “It appears there is a known problem with Garmin head units and if an ANT+ signal burst overlaps with a WiFi burst it will contaminate the ANT+ signal so that it cannot be decoded and dropouts result. So it appears the reception rate for the power meter is interrupted by the feature signal. This is something that Garmin needs to address and is common to all power meters with torque effectiveness features.”

      In other words, pedal smoothness and torque effectiveness were removed as features on the Precision due to power dropouts.

      I had pretty bad dropouts initially on my Precision, back when the metrics were enabled, but I’ve yet to have any dropouts on my Team Zwatt power meter, which also has these metrics, so I’m not sure that this is entirely the fault of Garmin and common to all power meters, as they note.

    • Vladimir Trofimov

      Thanks

    • dizpark

      Vladimir and Ray

      Out of curiosity I got into contact with 4IIII support on these two issues: Dual Pro availability (in Europe) and Pedal smoothness and Torque Effectiveness.

      – on availability – they are awaiting for a delivery from Shimano but have no schedule on availability.
      – on PS and TE – this s a direct quote from the reply “PRECISION PRO does not transmit PS & TE”

      so Ray you may want to double check this and correct the text of the review in GENERAL USE OVERVIEW if indeed these metrics are not transmitted at all.

    • Hmm, I’ll ask them tomorrow if they are/were still removed. Obviously, they were in there at the time of the review (you can see them in the data set), and others have followed-up afterwards that the were enabled initially, and then enabled on request.

      See this comment: link to dcrainmaker.com

      I’ll check with them on what the deal is these days.