• Amazon.com

PowerTap PowerCal In-Depth Review


A bit over a year ago CycleOps announced their latest devices – and with it their first power meter that wasn’t in a rear wheel hub .  CycleOps has a long history of power meter head units (and power meters), an area they’ve been at the forefront of for years.  When the product was announced, many within the industry were skeptical on how accurate a power meter could be based purely on heart rate data.  And further, for as low of a price as it was being offered (now down to $99).  So, I’ve dug in to find out and separate fact from fiction from FUD.

Like all my reviews, they tend to be pretty in depth (perhaps overly so) – but that’s just my trademark DC Rainmaker way of doing things.  Think of them more like reference guides than quick and easy summaries.  I try and cover every conceivable thing you might do with the device and then poke at it a bit more.  My goal is to leave no stone unturned – both the good and the bad.

While during the initial development period, I picked up a unit from CycleOps at Interbike that year (anyone could for free).  I have since procured my own final unit, which is what this review is based on.  If you find my review useful, you can use any of the Amazon or Clever Training links from this page to help support future reviews.

Lastly, at the end of the day keep in mind I’m just like any other regular triathlete out there.  I write these reviews because I’m inherently a curious person with a technology background (my day job), and thus I try and be as complete as I can.  But, if I’ve missed something or if you spot something that doesn’t quite jive – just let me know and I’ll be happy to get it all sorted out.  Also, because the technology world constantly changes, I try and go back and update these reviews as new features and functionality are added – or if bugs are fixed.


First up is the exterior box.  Note that there are a few variants of the PowerCal unit floating out there.  One includes just the PowerCal strap (combo heart rate and power).  Another includes the strap + an ANT+ speed sensor.  And the third includes a strap + speed sensor + calibration stick (ANT+ stick).

If you already have a Garmin Forerunner with an ANT+ stick, there’s no need to buy that stick package.  They all work just fine with each other interchangeably.  Same goes for the speed sensor.  In fact, I see little reason to buy anything other than the $99 package (just the strap).

That said, this particular unboxing includes the extra pieces.


Cracking the box open, you’ll see the heart rate strap transmitter pod looking up at you.


After taking the top off the box, we’ve got the following little baggies full of goodness.


Those bags include the PowerCal strap (left), the speed sensor (upper middle), the slew of zip ties for the speed sensor (bottom middle), and the manual that you won’t read (right).


First up – the PowerCal strap and the speed sensor.  Note that this isn’t a combo speed/cadence sensor, but rather just a speed-only sensor.  Also note that not all ANT+ capable units support the speed-only sensor.  Virtually every ANT+ unit out there supports the speed-cadence combo sensor, but less just the speed-only.


Here’s the manual.  We can pretend you’ll read it.


Back to the speed sensor – you’ve got the transmitter unit, and the small spoke magnet sticking up there.  You attach that to a spoke on your rear wheel, and the transmitter to your bike frame using the plethora of zip ties.


Here’s a bit better look at the heart rate strap itself.  In many ways, it looks just like any other ANT+ heart rate strap out there.


Ok, with the unboxing complete, it’s time to dig into the details.

Detailed Breakdown of PowerCal functional areas:

I’ve taken a bit of a different approach this time with the review.  Not substantially, but probably just enough to be noticeable to regular review readers here.  Given the PowerCal is essentially just a heart rate strap that also spits out a power number, I wanted to focus on the different scenarios, edge cases and functional areas of the strap.  I started off with section numbers in my review draft, but realized it actually made it kinda easy to walk through starting with the simple, and then getting to more complex scenarios.  Think of it like a school lesson book upon each previous chapter.

1) Setup, Installation, and Pairing with other head units:

Setup of the PowerCal is amongst the simplest device you’ll have to setup out there.  In fact, it’s not really any different than that of a heart rate strap.

And while it used to be that in the earlier pre-production PowerCals required that you calibrated them, that’s no longer the case.  After a 3rd party (Colorado University at Boulder) conducted a study on the accuracy of the units they found that there were no accuracy advantages in most cases by calibrating the unit (done via mini-FTP test).  The only thing it served to do was add more complexity and and more test workouts to users that otherwise might not ever wish to complete them.  But I’ll dive into this more later on.

With us ready to start pairing, you’re going to be pairing it twice.  Once for the heart rate strap, and then once for the power meter.  Some head units (like the Joule GPS) support a ‘find everything nearby’ function – but that’s about the only one that does (a cool feature).  Hence why most other units you’ll have to do the two-step tango.

First, we’ll take care of the power meter piece.  This will vary based on your exact bike computer, but you’re ultimately looking for the section that allows you to setup bike profiles/details and then pair the ANT+ power meter:


Once that’s done, you’ll usually see a device ID of some sort, and a message saying either connected or paired.


In some models, you can even get additional information about the unit as well.  Though not all bike computers have this.


Once your power meter is found, you’ll want to complete the same steps for the heart rate side as well.  Usually the heart rate settings are found in one of two places.  Either the person/user settings, or the bike sensor settings.  It depends on the model.  Ultimately though, you’re looking for something that says “Heart Rate Sensor” or “Heart Rate Strap”


Finally, a fun little note – if you attempt to calibrate the PowerCal using the automatic calibration button found in most bike computers, it will not succeed.  The calibration button found there is designed for direct force power meters, and not for PowerCal.

The PowerCal calibration function is very different, and I talk about that much later in this post.


2) Looks like a normal power meter on units


The most important thing about the PowerCal is that it looks like a normal ANT+ power meter.  As you saw in the previous section – it’ll pair like any other power meter does to any other power-meter capable head unit.

These include (not a complete list, just off the top of my head), the following units:

4iiii’s Heads Up Display
CycleOps Joule 2.0 & 3.0
CycleOps Joule GPS
Garmin Edge 500
Garmin Edge 705
Garmin Edge 800
Garmin Forerunner 310XT
Garmin Forerunner 910XT
Magellan Switch
Magellan Switch Up
Motorola Motoactv
Timex Global Trainer
Timex Cycle Trainer GPS
Various iPhone apps with Wahoo Fitness ANT+ adapter/case
Various Android apps with compatible phones (ANT+ chip on certain models, like Xperia Active)

With all of these units, comes the standard ANT+ power meter metrics that are typically available, these include the below – all of which work with the PowerCal:

Power (instant)
Power – Max
Power – Average

Additionally, any other data field offered on certain manufacture products that are dependent on the standard ANT+ data stream will work with the PowerCal, for example, these data fields:

Power (3-second)
Power (10-second)
Power (30-second)
Training Stress Score (TSS)
Intensity Factor (IF)
NP (Normalized Power)
Power Zones
% of FTP

Again, each of the above fields vary by head unit company – and not by the PowerCal itself.  It’s merely transmitting the wattage that these different fields rely on.  And of course, different companies can choose to implement the same fields slightly different ways – though most are fairly standardized.

3) Fluctuations in Power:

The single biggest difference you’ll notice between power numbers displayed by a PowerCal compared to most other power meters on the market is the fluctuation in instant power displayed on head units.  In other words, the consistency (or lack thereof) of the power numbers.

Now, it should be noted that virtually all power meters display some sort of second to second variation that often concerns folks new to power meters.  For example, a typical power meter will look like the below string (consider each number the following second).  This is from a PowerTap hub across 13 seconds.:


Now, let’s take a look at some numbers from a PowerCal (these are aligned to the same 13 seconds as the PowerTap above)


What you see here is far greater variation between each second, as well as far more ‘super-high’ and ‘super-low’ numbers.  For example, the 0’s and the 35/68.

Now, when looking at averages (and I just picked 13 random seconds), we see the following:

PowerCal: 135w
PowerTap: 114w

I won’t get into averages in this particular section, but you can see that while their methods are different, the overall averages are in the same ballpark (though, not the same base path).

To illustrate this a bit better, I’ve made the following video – which I’ve placed two power meter display units next to each other.  The left unit (bigger Edge 800) is displaying power from the PowerTap, whereas the right unit (smaller Forerunner 910XT) is displaying power from the PowerCal.  Both units are configured and setup identically, and both started at the same time.

Data displayed on Edge 800 (top to bottom): Instant Power, Power 3-second avg, Power 30-second avg, Lap Power

Data displayed on FR910XT: Instant Power (upper left), 3-second power (upper right), lap power (lower left), 30-second power (lower right).

What you’re looking at is how different the 3s (3-second) and 30s (30-second) power is between the two, and which one is most useful for pacing.

Video of instant-power

I’ve also placed the lap average on there as well, to allow you to get a sense for how the overall average of those units are comparing.  Note that overall the units remain fairly stable, and fairly close.

4) Power Analysis After the fact – what the data looks like:

Before we get into some of the power files, I wanted to briefly cover what data looks like from the PowerCal, compared to regular direct force power meters.

At first glance, with some form of smoothing on – you may not notice much of a difference.  It looks mostly like normal power meter data:


But as you remove the data smoothing you start to see just how jumpy the data is:


Compare a PowerCal and PowerTap on the same ride – and note how different the graphs look.  Power meter data is always jumpy in general, but the degree that the PowerCal is jumpy is the interesting tidbit.

In the PowerCal (above), you’ll see that the data doesn’t hit the floor (bottom, zero-value) nearly as much as the PowerTap.  This is because the PowerTap is instantly picking up when I stop applying force.  So if I pause pedaling for just one second, it’ll capture that.  Whereas the PowerCal takes a longer reaction time as it is based on heart rate.


This is even more visible when you look at raw numbers in something like Excel.  Below, a few columns of numbers – one on a PowerCal, another a PowerTap, and a third, a Power2Max.  Ignore the correlation between them (well, you can look if you want) – instead, note the line after line differences (going from top to bottom).  The change is far more significant between each value on the PowerCal than the PowerTap.


We’ll get into what this means in a bit.

5) Short duration power accuracy (sprints/intervals)

One of the most common questions with the PowerCal is how it handles short intervals from a power measurement and responsiveness standpoint.  The reason being that since PowerCal is based on heart rate data, heart rate data will lag slightly behind power output.

For example, if you’re just calmly riding along at an easy wattage, and then burst into a all out sprint – it may take 5-20 seconds for your heart rate to show the impact of that – meanwhile, your wattage on a direct force power meter (normal power meter) would have shown that immediately.

In the case of PowerCal, I did some tests comparing lap averages over different lap durations.  I went out on a closed course and simply held sustained efforts for each length of time.  These weren’t set to me holding any given specific wattage, rather, me just holding a heart rate value that seemed interesting.  Effectively, these were intervals.  Though, the exact heart rate zone isn’t terribly important.  What’s important first is how accurate the PowerCal can be during shorter durations (because your intervals will vary just like mine).

Here’s the results (click to expand):


As you can see, the PowerCal seems to get relatively close down until about 30-40 seconds.  At which point, the rate of change exceeds the PowerCal’s ability to measure the sprint.  It did somewhat find on a 30-second attempt (#9), but had more problems in the 40-second one just after that.  Above those times however, things were actually pretty close most of the time.

6) Full workout power accuracy (longer duration)

Now that we’ve covered the shorter sprint scenarios – how well does it hold up over the course of a workout?

Well, surprisingly well.

And that makes sense.  At $99 the unit primarily targeted towards those interested in full-scope workout averages.  Meaning, less focus on detailed lap by lap and interval analysis down to the watt.

In fact, this generally seems to align with most of the anecdotal data I’ve seen across many different cycling related forums.  There are some outliers, yes, but most folks are pleasantly surprised at how well total averages perform.  For fun, I pulled my four most recent rides:


Of course, total averages don’t tell the full story.  And, many ardent power meter supports like to point out that total averages are useless – since they don’t show you important values like max efforts and what went into that.  As noted earlier, you can arrive at a total average number many different ways.  It’s how you arrived at that number that makes up a training session.  Hence why other values besides averages are so important.

That said – for most individuals looking at buying the PowerCal, they are likely using simple speed today (MPH/KPH).  Any cyclist will tell you that like other metrics  – simple speed is just as dependent on wind, terrain, environmental factors like snow or rain, or even ones ability to navigate trail or road traffic.

Thus, in many ways the PowerCal isn’t much different here.  But it does provide a overall wattage value to work with.  Something that a simple speedometer doesn’t.  Different folks will be able to interpret that differently.  But most folks would be able to interpret a plotted graph over time showing improvements in average wattage/power over the course of a season.  Hence why I still think there’s value here, assuming one understands the limitations (which you’re seeing I’m working through section by section).

7) TSS/NP/IF (Training Stress Score/Normalized Power/Intensity Factor)

These metrics are amongst the most commonly ones used when measuring the impact of ones training with cycling.  Be it either in conjunction with your larger workout load (TSS/IF) or on a per-ride basis (NP).  You can find lots more background information on these metrics here.

Both metrics at first glance level work just fine with the PowerCal with any power meter that support these Training Peaks metrics.  Today that’s limited to the CycleOps units, as well as the Garmin Edge 500/Edge 800/Forerunner 910XT and the Magellan Switch Up.

However, deeper analysis shows that due to the high variability within the PowerCal data (as seen in fluctuations), you’ll likely get slightly skewed numbers.  For example, the high spikes can lead to changes in these metrics – as it assumes you’re putting out brief extremely high level efforts (similar to a sprint).  In real life, the act of repeated hard high wattage sprints with longer rest breaks is normally more impactful (training load-wise) than a low-intensity sustained effort.  But the opposite is true as well, in that PowerCal often puts in many lower-value numbers that make it look like you’re riding easier than you are.  Thus, when translated to emulated readings (that the fluctuations induce), you’ll see non-realistic metrics.

Taking a simple comparison I’ve taken a ride below that the PowerCal performed ‘rather well’ on.  Meaning, that its overall wattage was quite similar to that of a PowerTap on the bike at the same time (3 watts).  Running these metrics, you can see the differences below:


Both of these metrics were calculated online using TrainingPeaks in the same account – to eliminate any head unit discrepancies with setup of TSS/NP/IF on the unit itself (both recorded all zeros and at one-second intervals – which is how I record all test data).


You’ll notice slight discrepancies in other metrics as recorded by the different units, though non affecting TSS/NP/IF.

8) Indoors Riding (Trainers)

I tend to do about 80% of my workouts indoors on a trainer.  Both because you generally get higher quality workouts on a trainer (it’s relentless), and because it’s sometimes just easier living in a city (you get more bang for your training buck).

In doing so, it’s interesting looking at some of the numbers related to the PowerCal.  These workouts were part of larger trainer accuracy tests I was doing, so it made it simple to grab the numbers for the PowerCal.

You’ll see some of the first portion of the structure within the workout I was doing, though I didn’t detail it all out as much of it was repetition.   Ultimately though, the numbers speak for themselves.

Note that as is the case in all of my power meter accuracy tests – the power meters are calibrated (where applicable) at the 10-minute marker, just after the warm-up watts.  The labels on the left-side correspond to chunks of the workout.  For example ‘Warm-up Watts’ is a 10 minute section, ‘Calibrate Watts’ is a 2 minute section where I don’t stop anything recording, but do complete calibration.

Trainer Workout #1:


Trainer Workout #2:

This was part of a interval workout of sorts I did.  Again, you see that the overall numbers are fairly close.  Each interval was 60 seconds long, and each rest the same.  You’ll notice that the PowerCal overestimates the rest interval by quite a bit – likely because my heart rate was rather high.  Whereas the other power meter instantly recognized the lack of wattage. All my rest intervals though are still pedaling.  There aren’t any stoppage points here.

I picked a few random intervals to show in the table below (as opposed to painstakingly doing the Excel math for all of them).  The intervals were not at a set wattage per a CompuTrainer (or similar), but rather in a rough range, hence why they vary interval to interval.


Overall, I see week after week pretty impressive results when it comes to trainer accuracy of the PowerCal.  It is interesting in the above workout to see what appears to be some drift in the older version of the Power2Max.

9) Coasting/Descents and the results

Perhaps one of the more fascinating things to look at is how PowerCal handles descents – or coasting in particular.  Obviously you can still descend and put out a lot of power (as I painfully learned while riding with some pros in Colorado last year).

But in general, if you’re coasting, you aren’t likely putting out much power.  Often called ‘soft-pedaling’, you may be just putting out a few dozen watts, simply enough to turn the crank around slowly.

I took the below snippet from a recent ride as I descended down a hill.  Let me walk you through what you’re seeing on the charts.

Brown: This is the hill, or the descending of altitude.  From left to right, you see that I’m largely going downhill.

Teal Line (light blue): This line is my cadence.  You’ll see it’s dropping often down to 0 (the bottom).  But generally being fairly light I’m just pedaling around 70 or so RPM – not pushing it at my usual 90-100rpm.

Blue Line: This is my heart rate.  The scope of the graph makes it appear as though it’s a constant – but in reality, at least for the first portion, it goes down.

Red: Power.  Simple enough, this is the PowerCal’s power output.

Now, with that background, flip to after the picture and I’ll explain what’s going on.


First look at the left third of the chart, and in particular, the bottom portion where the red power and cadence are displayed.  Note how there’s a slight delay between when I pedal (and the value jumps from zero), to when the power is registered?


You can see it pretty clearly above – teal always leads the red.  Like cat and mouse.

Now, if you look up at the heart rate, you’ll see tiny little jumps each time I start pedaling. This is logical, since for every action there’s some sort of reaction.  In my case the energy exerted pedaling requires some level of heart rate (effort).  Each yellow highlighted section shows the increase in heart rate, causing the increase in power displayed.


Of course, cadence as a metric isn’t taken to account by PowerCal.  Rather, I’m just using it as it’s a very easy metric to show what my pedals are actually doing above.

Now the important thing here is that it’s about rate of change – not about straight heart rate.  Note that as I come down in heart rate (blue) and start to flatten out, the unit realizes I must be applying more wattage.  Otherwise, my heart rate have continued to decline.  Then notice that as the rate of change decreases (heart rate), it means I’m applying less force – and thus less power.  And therefor you see the red start to taper out.


Of course, if you look at the teal line, you see this confirmed within cadence.  Now, I could have simply changed gears and lowered by cadence but increased my power.  But that’s not what happened.

In fact, below, taken from a PowerTap – shows a fairly similar power curve:


Finally, looking at stopping (when my bike stops rolling, generally not due to a crash).  In the below graph, I stopped.  For what I assume was a stoplight/stop sign, though it’s not clear.  What is clear is that my speed went to zero for about 15 or so seconds.

Speed is shown in green.  Whereas power is shown in red.  You see that as you’d expect, power zeros out before speed (you stop pedaling), and then speed flat-lines.  It won’t always be quite as clean and with complete zeros as this (note the tiny little red bump up in the middle of the first stop) – but it gives you a good idea of what it looks like.


In summary, it’s not actually at all about coasting or descending – rather, it’s actually just about heart rate.  More specifically, change in heart rate, and that rate of change.

10) Calibration – You can still do it.

The PowerCal calibration option was effectively removed as a requirement this past summer upon release of PowerCal.  Initial pre-release information and units required/preferred a calibration test occur not only prior to use, but also every “4-8 weeks, as fitness levels change”.

However, upon release this summer, CycleOps removed the calibration requirement, noting the following (in an e-mail to the Wattage group):

“PowerCal can be calibrated but based on the study conducted at CU-Boulder there wasn’t any indication it addressed any of the expected short falls relative to accuracy so it’s not really worth the effort. Keep in mind this is terms of a sweeping recommendation across a wide population of athletes, there were instances of the calibration significantly improving accuracy across all activity types for some users. We just couldn’t find a correlation between anything specific for those that the calibration worked for and those that it did not.” – Jesse B. – CycleOps.

As noted, PowerCal can still be calibrated, but in my testing I haven’t seen any substantial differences between the initial test unit that I calibrated the first time around, versus the new unit that I have that doesn’t require calibration.

For those interested in calibration however, the test is essentially a threshold test of sorts, and the official documented procedure as as follows.  However, it does require the use of a normal power meter (direct force power meter), such as a PowerTap, SRM, Quarq Cinqo, Power2Max, etc… Ultimately, you’d want to ensure that power meter is correctly calibrated.

In fact, here’s the full list of things you’ll need:

1) Power meter (direct force)
2) Heart rate strap
3) Head unit (bike computer that can record the HR and power data)
4) ANT+ USB stick (found with various Garmin devices, some PowerCal packages, or solo)

Then, you’ll go ahead and pair that power meter to a head unit (bike computer) of your choice, along with a heart rate strap.  You’ll want to ensure that can be imported into the CycleOps PowerAgent software (downloadable on their site, used for analyzing workouts from CycleOps devices).

Once all that’s set, perform the following test:

Calibration Test Protocol

5 min warm up
3 min Very Easy
3 min Easy
3 min Moderate
3 min Moderately Hard
3 min Very Hard

In their initial documentation, they included the below graph as a general indicator of what you’re looking for consistency wise:


Once you’ve got the data imported into PowerAgent, you’ll want to go ahead and open the workout up in PowerAgent.

Highlight the section of the ride beginning with the warm up to the end of the fifth stage. Go to Tools > Configure PowerCal. There will be a pop-up window with the calibration highlighted. Click OK. Another pop-up window will appear confirming the new parameters. Click OK. A second pop-up window will appear asking if you would like to update the PowerCal. Make sure the ANT+ USB stick is in (you’ll need one by the way) and click OK. When finished it will confirm success.


When finished and ready to workout pair the PowerCal as a Power and HR sensor and you’re ready to go.

11) Running (why not?)

Last but not least…

Like Mythbusters, I like to take this beyond the intended myth.  And this is one of those cases.  Many folks have pondered how PowerCal handles running – and whether there could be any value pulled from it.  Of course, today there isn’t a direct equivalent to ‘wattage’ for runners.  There’s no ability to correlate an effort on a hill with that on the flats.  One could have two equal wattage efforts and that would clearly be seen on a bike – but far less so with running and pace.

Ultimately, PowerCal will happily provide you with wattage data for your run.  In fact, PowerCal will happily provide you with wattage data anytime your heart rate is pumping.  Be it running, yoga, fencing or simply having sex.  If you got blood flowing, PowerCal’s there to capture it.

But correlating that data to something useful is where it becomes challenging.  For example, on a treadmill workout today, beyond the first two minutes, the treadmill was set on a specific inline and speed.  It never waivered.  In the real world – that would mean that my output was the same.  But in the PowerCal world, it instead wavered based on heart rate – which slowly climbed (mostly due to lack of cooling).

Personally, I’ve found metrics like Training Peaks Graded Pace far more valuable for measuring run to run performance across differing terrain on different days.

Now, make no mistake – wattage or an equivalent will absolutely come to running.  Not this year, likely not next, but it’s out there – and there’s a number of different teams and companies working on it.  Of course, just like cycling in the early wattage days, it’s going to first look like a jumble of numbers and then take years to get to the point of really being able to make the most of the data.

It’ll come though, someday.


At this point I suspect you probably have a pretty good idea of whether or not the PowerCal is a good tool for your training needs.  But, before I give you some parting thoughts, here’s a quick table of pros and cons.

Pros and Cons:


– Cheap, really cheap
– A gateway drug to full blown power meters
– Compatible with any ANT+ power meter device, easily integrates with existing devices
– Includes ANT+ heart rate strap functionality as well (you can use that part standalone for a run, which I do all the time).
– Can be calibrated, if you want to venture down that path


– Shorter duration accuracy is rough
– Longer duration accuracy depends on many variables
– Pace fluctuates quite a bit
– May not be as accurate for everyone, highly individualized
– Calibration procedure requires repeated testing, may not improve accuracy

Final thoughts:

PowerCal isn’t marketed as a 100% accurate power meter.  Nor as a tool for elite athletes (or any advanced athlete) to use as a hard core pacing device in a race or even day to day training.  Instead, what it does offer is a low-cost method of getting a rough order of magnitude of your power level on a given ride.  CycleOps is rather straightforward about this, from their own site:

“The PowerCal is not as accurate as a PowerTap and not intended to replace one.  Research has shown varying degrees of accuracy based on individuals and types of riding. Accuracy will depend greatly on the individual and type of riding.”

Now there are many alternatives that can estimate power information after the fact – some of them free or relatively cheap.  However, most of them are just that – after the fact, and separate.  If you want some sort of integrated metrics that automatically show up in whatever bike computer you’re using – there’s really only two choices: PowerCal, or a normal power meter.

Note that you shouldn’t take a PowerCal wattage number and attempt to compare it against someone else’s power meter number.  There are just too many variables.  It’s better for plotting progress against yourself over time.

In my mind, the perfect target audience for something like PowerCal is actually my Dad.  He normally rides about 100 to 150 miles a week, but he doesn’t race (triathlon or cycling).  Rather, he rides to enjoy riding and to stay fit.  Today, he uses simple speed on known courses/routes to determine his improvement week over week.  While there are pitfalls to this, that’s the only tool in his (and most cyclists) bag to work with.  Something like the PowerCal would give him a general idea of his improvement within the season.  It wouldn’t be perfect, but it would work – as seen by not only the vast majority of the data here in this review, but also many other reviews and data points out there.

But as noted, it’s not for everyone.  Personally, I wouldn’t use it day to day in my training, because my training is focused and specific enough that I need to ensure my numbers are consistent and accurate from session to session and within a session at shorter intervals than the PowerCal can respond to.  Though, I would point out that I do believe the vast majority of power meter users today don’t get truly accurate and consistent numbers session to session.  Instead, they look at trends.  Merely looking at some of the differences you can see above between the PowerTap and the Power2Max in my data is a obvious indication of that.

Ultimately, the PowerCal is just a tool.  As I always note in power meter related reviews, you still have to go out there and do the hard work to get better.  This is simply one more (low-cost) tool in your bag to try and capture, analyze and make improvements on your work.  Good luck!

Found this review useful?  Here’s how you can help support future reviews with just a single click!  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 pickup the PowerCal below. 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 $75, you get free US shipping as well.

Additionally, you can also use Amazon to purchase the unit or accessories (though, no discount on either from Amazon).  Or, anything else you pickup on Amazon helps support the site as well (socks, laundry detergent, cowbells).  If you’re outside the US, I’ve got links to all of the major individual country Amazon stores on the sidebar towards the top.  Though, Clever Training also ships most places too and you get the 10% discount.

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!

Finally, I’ve written up a ton of helpful guides around using most of the major fitness devices, which you may find useful in getting started with the devices.  These guides are all listed on this page here.

Post a Comment

Your email address will not be published. Required fields are marked.
If you would like a profile picture, simply register at Gravatar, which works here on DCR and across the web.

Click here to Subscribe without commenting

Add a picture



  1. Ray, for the trainer intervals, what power meter were you using for pacing your intervals? After some intervals there is a big discrepancy between the Power2Max and Powertap. Are you using the new P2Max with that temperature compensation update?

  2. Hi Ray,

    I am a huge fan and supporter of your blog and did end up making a purchase through clever training in support of you. However, I have never had such poor customer service ever in all my experience of shopping online and am hugely disappointed in my experience.

    I’ve left countless voicemails and emails with them, only to have them be unanswered. I hope you can understand my frustration.

    From now on, I will only be supporting you via your amazon link.

    Looking forward to your upcoming posts.

  3. Hi Rafael- This is with the older Powr2Max. However, the only difference I saw was that one that I noted above. Interestingly, indoors.

    Hi Joey-

    I’m super bummed to hear that. Can you shoot me a note with your order number. I’d love to follow up and ensure it never happens again. But I do want to thank you for your support.

  4. I don’t get to see pictures at work, so I’ll have to read through this again later, but my main concern is in regards to your last paragraph where you write about who you feel the powercal is intended for.

    If it shows power based off HR, it is basically using an average power value for a given HR (I’m sure it’s very complicated though and probably has to do with how fast your HR increase among other variables). Right? So, if you improve over the course of the season to where (form a powertap) you power increases 20 watts at the same HR, how would the powercal see this?

    The powercal to me just sounds like they took the idea of matching a power curve from a trainer to speed numbers, but applied to to a power curve based off of HR. Can you comment on this?

  5. Anonymous

    A power meter’s appeal is accuracy. Not too much of that is offered by Powercal, but that is reflected in the package. Power2max cant be afforded the same margin of error. A comparison of accuracy and precision would be appreciated.


  6. So. I have a few questions.

    1. I didn’t see anywhere that you entered your body weight. in terms of actual wattage that would appear to me to be an essential calibration metric.

    2. If all we are interested in is the final whole of ride average then why not just put it into the post ride analysis software. Do you know what the patent coverage is like? can you advise if there are any patent markings on the box/documentation?

    3. You note that it doesn’t make use of speed or cadence. this is strange as it would appear to me to be a very sensible thing to do. it would certainly help solve the coasting problem and I suspect could be used to derive more accurate power models as well. Given that it’s likely to have upgradeable firmware I wonder (again subject to patent exclusion) what could be done on the 4iii’s Viiiva to do something similar.

    4. If I can find a cheap one somewhere I might give it a whirl on the Concept2 Erg and see how the numbers correlate.

  7. Anonymous

    I’m curious to know how this would work for those of us on certain heart medications, such as beta-blockers, which artificially lower our heart rates. I’m guessing since it relies heavily on heart rate data that the numbers would be very inaccurate. Does the manual say anything about this possibility, or do they simply assume that people with conditions simply aren’t advanced enough to want power meter tech?

  8. you missed an important ‘Con’. How would you ever be able to tell if you are getting fitter?

  9. DS

    Similar question to Chris’s: how does it show power improvement over a season? If it’s based on HR, wouldn’t it only show a power increase over a season if there was an increase in average HR over the season? And in fact, HR at a constant speed should drop over a season. It seems that it would need to incorporate speed in its calculations to show power increase over a season.

  10. One way that it might add something over normal post-ride analysis would be if the module internally measured R-R inter-beat timings, and factored that into the power calculation.

    That’s something that’s missing with normal ANT+ HR, and where Suunto can score with their own straps (although that will presumably be lost e.g. on the Ambit if you use an ANT+ HR when that firmware update hits).

    So, do we know if the Powercal can do this?

    If not, it seems its only real advantage is in real-time data, as Ray says.

  11. Anonymous


    I know you’re a fan of SportTracks. I’ve been using the GPS2Power plug in, which uses weather and Garmin data to estimate power. You can look at a graph of power over time as well as average power for the ride.

    Obviously the ST plugin is only after the fact analysis, but given your comments about your dad (who sounds a lot like me:)) using the PowerCal to look at improvement over time to time I’m wondering if you could comment more on the relative application and value of the ST plugin and the CycleOps device? Thanks!

  12. Ray – it’s weird that the P2max would drift that much considering the indoor ride shouldn’t have that much temperature difference. P2Maax was on my considerations to rplace the powertap, but that scared me.

    cdmackay the Forerunner 610 and 910xt can record r-r data to be analyzed with Firstbeat athlete, with the regular ant+ hr strap.

  13. Is powercal compatible with the soft strap of Garmin Premium Heart Rate Monitor?, i think will be more confortable than the powercal. Thanks.

  14. Hi Chris-
    RE: Mapping of HR to HR values

    Sorta, but not quite. There isn’t a 1:1 mapping, meaning my 140bpm isn’t the same as your 140bpm, thus, you can’t explicitly map it to say – 200w – for both of us.

    Beyond that, much of what they are doing is pretty much trade-secret, which is somewhat logical they don’t want to say – as that’s basically all there is to the product (the sauce).

    Hi Anon/hu3ain-
    RE: Power2Max

    Correct, I have a new Power2Max unit that’s getting installed on there, but it wasn’t on there then. The only one you saw the variation was during inside interval interestingly. Many of the others I actually re-calibrate a few times along, knowing the temp change shifting limitations of the Power2Max.

    Hi Chris-
    RE: Body Weight

    No, body weight needed/utilized. Wattage has no bearing on body weight, only w/kg (which is head unit driven). Body weight is also used for calories.

    RE: Why not just average software post-ride

    As noted above, it would still allow you to do longer-interval wattage sets (roughly about 30-40 seconds) and get half-way decent data.

    Additionally, it then ties you to a given software suite (i.e. Sport Tracks, etc…).

    RE: Patents

    The box photos I have handy (I’m travelling) don’t show one, but I do know there are patents either pending, or approved, from previous conversations with them.

    RE: Speed/Cadence

    Originally, very early on in the prototypes there was logic in the Joule unit to make use of speed sensor with it. Though, that wasn’t carried over to other units.

    Ultimately, there’s likely the ability for it to talk directly to another ANT+ sensor (depending on the chip in there), thus potentially allowing you to pre-pair it with a given speed sensor.

    Hi Anon-
    RE: Heart medications

    In general, I think you’re good on data as long as the medication doesn’t affect the rate change. Meaning, as we age, our max HR values slowly decline (i.e. a younger person could relatively easily hit 190bpm, but an older one not as much).

    Hi Morey/DS-
    RE: Being able to tell if you’re getting fit

    Power alone doesn’t tell if one is getting fit. It’s always two variables. Power + X. Power + Heart Rate, Power + Time, etc… I can easily simply increase my power over the course of the season, but that wouldn’t show I’m getting fit. What would show that is a set/constant power + a decrease in heart rate (average). Or, a known TT course (no wind) + a decrease in time and an increase in power. It’s no different than any other PM out there in that respect.

    For me personally, I use HR + PWR on a trainer. At a given HR level, I know my wattages, and I aim to improve those (generally I do that).

    Hi CD-
    RE: R-R

    R-R isn’t actually a function of ANT+ HR, but rather, a function of the head unit recording the data. Companies pay FirstBeat to utilize the technology on a per product basis (i.e. FR610, FR910XT, etc…). Rafael also later on noted this (albeit after your comment) as well.

    Hi Anon-
    RE: GPS2Power

    Indeed, he could use that as well. Doesn’t solve the trainer piece, or being tied to a given application – but it’s definitely something he could use.

    Hi Rafael-
    RE: P2Max

    Indeed, I’m looking forward to getting the new unit on there.

    Hi Xorga-
    RE: Premium HR Strap compatibility

    Yes, no problems in swapping to the absolute latest strap. For those curious, it’s also compatible with the Polar HR strap (not the Polar pod or watches, just the Wearlink strap).

    Thanks all!

  15. Alex Simmons

    Thanks for the detailed review.

    I’m unclear on how it adjusts its power estimates for riders of vastly different fitness levels.

    Regarding this comment:

    “Hi Morey/DS-
    RE: Being able to tell if you’re getting fit

    Power alone doesn’t tell if one is getting fit. It’s always two variables. Power + X. Power + Heart Rate, Power + Time, etc… I can easily simply increase my power over the course of the season, but that wouldn’t show I’m getting fit. What would show that is a set/constant power + a decrease in heart rate (average). Or, a known TT course (no wind) + a decrease in time and an increase in power. It’s no different than any other PM out there in that respect.

    For me personally, I use HR + PWR on a trainer. At a given HR level, I know my wattages, and I aim to improve those (generally I do that).”

    The only measure of fitness that matters is whether your power and/or W/kg for durations of interest/relevant for your goal events has improved.

    It matters not what your HR does. If you can’t put out more power, you are no fitter.

    I’m not seeing how this device can determine changes in actual power output.

    And a P2M < Powertap readings tells us at least one of them is wrong. Do you know which? (I do sell some DFPMs but like to stay well informed on what’s out there).

  16. Hey Ray,

    Cool review, really considering buying this device, cause it is a cheap start to power meters.

    But I have only one question. I understand that the powermeter is vary sensible for heart rate changes and couples this to increase/decrease of power.

    But how can the strap “see” the difference between my father (80kg, pushing 100 Watts at 170 bpm) or a Tour de France rider (80kg, pushing 300 Watts at 170 bpm)?

    As far as I understand they will result in the same power output…

  17. Anonymous

    Hello Ray

    Nice Blog you have I allways enjoy reading the reviews.

    How do the results of the PowerCal relate/differ to the powerresults shown in Strava.

    Beside the fact that you can see your results while riding of course and in Strava it is shown after.


    Wimm (Netherlands)

  18. Anonymous


    Values of NP and VI are too far off for the Powercal to be used as a pacing device. The PW:HR ratios in both screens are typical of a perfectly paced event and a bad strategy (-7.06%).

    Power measurement for runners would be awesome. Wished that the normalized graded pace metric would feature in 910xt.

    Amazing review DCR

  19. Hi Alex (and Tom)-

    RE: Adjusting for different riders

    This is the part that pretty clearly falls (unfortunately) into the patented part. I’ll try and see if I can get a bit more clarification on it. I’ve asked a few times in person, but haven’t got any clarity. In looks at many other data points by different riders posted out there (with very different power profiles), it does seem to have enough logic built into it that it works (for most, albeit not all). I will note that Jesse from CycleOps did make this comment back on ST a while ago:

    “This was our initial concern as well and why we assumed a calibration would be needed. However, in testing that assumption in the lab it was pretty clear the calibration did not provide a significant improvement across our intended customer base.

    We concede the product won’t work for Lance [Armstrong]. We’ve set it up for a reasonably fit athlete knowing that the established issues with using heart rate to determine energy expenditure are bigger limiters for PowerCal than the absolute power to heart rate relationship of a given individual relative to another.”

    RE: W/KG as a measure of fitness

    You noted “The only measure of fitness that matters is whether your power and/or W/kg for durations of interest/relevant for your goal events has improved.

    It matters not what your HR does. If you can’t put out more power, you are no fitter.”

    Actually, W/KG isn’t a measure if fitness change. It’s merely a stated value. Ultimately, I can change my watts/kilogram by simply putting out more power. That doesn’t mean I got any fitter. It just means on day 1 I did an easy ride, and day 31 I did a harder ride.

    You always have to combine power output with some other metric to meausure improvement. Time, distance, HR, something. Unless you’re talking a straight FTP test, but even that has defined parameters. That’s true of any power meter.

    RE: P2M < PowerTap Yes, as noted above, in that case where the P2M was showing odd numbers (I put it below the chart as well), it’s pretty clear the P2M was having drift issues (common for the older units) – something I can easily see in the chart. Outside I’m pretty good about doing a number of calibration checks every 15 or so minutes. Though that time indoors I’m surprised to see such a variation. Again, for that particular one, the PowerTap data alongside makes it fairly clear what’s going on. Hi Anon-
    RE: Strava comparison

    Hmm, I’ll upload a few of those rides to Strava a bit later on tonight and see how the numbers mesh. Fun idea.

    Hi Anon-
    RE: NP/VI

    Definitely agree. However do note that those two screenshots showing PW:HR ratios weren’t a race, or anything paced. It was merely a ride with plenty of city traffic involved on both front and back ends. :)

    Thanks all!

  20. Hi Ray,
    great review, as usualy. I got excited, that I would finaly get wattage data for my running. I purchased the unit from Clever Training already. I was well aware of limitations of the PowerCal (thanks to your review), but I was unaware of limitations of my FR910XT. In Run profile the watch does NOT show Power values! Does it mean, that if I want to use PowerCal while running, I must set watches to Cycling profile? Or is there other way around?
    Any advice appreciated!

  21. Meer Nederlanders die er eentje willen bestellen? Dan kunnen we een groep-aankoop doen?

    (Any people from Holland wanting to order one? Maybe we can split the order costs by Clever Training.)

  22. Richard Lunt, UK

    Ray – Excellent review, as ever. I do short time trials and the Powertap (that I rent) is good for ensuring that I don’t go off too fast at the start, when heart rate takes 3 or 4 minutes to level off. Do you think the algorithm would help pace the early stages of a time trial properly and be useful for (15k and 40k) time trials generally?



  23. Anonymous


    Since heart rate is the only thing being measured, shouldn’t power wattage be available from any heart rate device as a post processing function? I know “Ride with GPS” does some sort of power calculation in any activity that captures heart rate. During this after workout processing, the lags could be determined and factored out of the calculations.

  24. Ray- you’re right about power, but you’re getting lost in the semantics. Unless there’s something I’m missing- There’s still an important CON to this device. Let’s say last year I was able put out 200w for 20min at a HR of 150. this year I’m able to put out 230w for 20min at a HR of 150. How would the device know? Lack of measurable improvement is a lack of an important motivational as well as practical item.

  25. I was told I needed to buy the Powercal with the speed/cadence sensor if I didnt already own a ant+ speed/cadence sensor. Can you confirm that the powercal doesnt use either speed or cadence to calculate power and therefore I don’t need to clutter my bike with the sensor

  26. Hey, I read your post from last year about riding with the pros…would you consider putting out a “DCRainmaker” cycling kit? I’m sure there are enough people that read your stuff that would pony up for a kit. Think on it.

  27. Juro

    I think one way how to know the difference in the case “Let’s say last year I was able put out 200w for 20min at a HR of 150. this year I’m able to put out 230w for 20min at a HR of 150” is the factor of how fast does HR change towards the 150 bpm in these 2 scenarios. It seems the unit measures wattage using HR changes, not absolute value. An untrained person’s HR increase pattern should be different.

  28. Victor

    Xorga and Ray,

    I purchased the PowerCal a couple months ago and thought the same thing about the latest strap being more comfortable. The powercal did not work with the latest garmin premium strap with the hook attachment. Were you able to get it to work Ray?

    Anyways, I ended up returning the strap. It was more for post workout analysis and was rather useless during rides which I was more interested in.

  29. Hi ray,

    I can see this is an affordable way to get power data India garmin device, but couldn’t this all be emulated with an alogorithm within a smartphone app, or ultimately garmin firmware? There is no need for the info to be churned out of the HR strap itself?

    I can still see a market for this though for people with existing sports watches etc.


  30. Hi Dalibor-
    RE: Run watch

    Correct, the running profile on the FR910XT does not allow connect to a power meter. Thus, you have to use the cycling profile. That’s what I did above (about to add in an example showing data while running here in a little bit). About the only unit that you can create a ‘custom’ blend on is the Magellan Switch/Switch Up – which would allow you to pair to the power meter, but have all the metrics shown in ‘runner-friendly’ pace.

    Hi Tom-
    RE: Holland Group Buy

    If you find more interest let me know, also, I can also add it to the Week in Review.

    Hi Anon & a few others
    RE: Post-processing options

    Yes, absolutely – there are definitely other options out there, with varying levels of input and success for each. Ultimately though, the appeal of this product over those is the lack of requirement for post-processing. Of course, different strokes for different folks.

    Hi Morey-
    RE: CON

    Now I understand what you’re getting at – which is that your concerned over time if your fitness improves, your power will effectively ‘drift’. I’m not seeing that as the case. I used a unit last fall when my fitness was notably higher, and then compared it to this fall/summer, where my cycling-specific fitness was lower. I’m seeing them track pretty closely. Ultimately, that’s why the product ‘works’ across people of differing fitness profiles without calibration. Otherwise the product would just work for me – Ray – and nobody else.

    And remember, there is no direct mapping between a given BPM value, and a given power wattage. That all comes with their patented algorithm piece, which I can understand why they are hesitant about sharing.

    Hi Tosin-
    RE: DCR Kit

    It’s something I’ve looked into, but first need to find a kick-ass graphics person to make something that’s both classy and awesome. Someday!

    Hi Victor-
    RE: Straps

    They definitely should be compatible. I know I’ve swapped it back and forth without issue at some point over the last few months. Let me double-check again on that one when I get back from this trip, but I’ve been mixing and matching virtually all of them for a different review without any issues.

    Hi David-
    RE: Emulation in-phone app

    Yup, absolutely as above. I’m sure there’s a few apps out there I don’t know of (I know of ones doing it post-ride and on computer/site). But ultimately, I’m sure we’ll see more – both apps and refinement of the algorithm from others.

    Thanks all!

  31. Interesting. I wonder how the HR to Power relationship works. In cycleops’ defense- I have noticed for myself- that as my FTP has gotten better- one of the things that changed was that I am able to sustain a higher HR for a longer period of time. This may be the opposite of running, where as I progressed, I was am able to run a faster pace at the same HR.

    These relationships generally aren’t discovered in a vacuum by companies like Cycleops. For instance- for the Nike+ they used 40 year old research that defined the inverse relationship between foot ground time and speed, which is surprisingly consistent person to person, allowing them to develop a very inexpensive foot pod. So- perhaps there’s a research paper out there that forms the basis for the HR to Power model they capitalize upon. Might have to do with HR rate of change- both up and down, that gives a metric of fitness level and then the power output is extrapolated based on this factor? Maybe they hired Coggin as a secret consultant?

  32. I’ve had a PowerCal for almost 2 months now. Your review pretty much hit the nail on the head.

    For post-ride analysis I find that hrTSS is more ‘real’ than the PowerCal TSS. However using the PowerCal for intervals of 5min plus (with TrainerRoad) gives a very similar output to TrainerRoad (for TSS and IF).

    In addition, the PowerCal is of great use when on travelling, and having to use a gym or spin bike, once you know what your FTP is on the PowerCal.

    What do you think the advantages are of getting the PowerCal calibrated; have you carried out any testing with a calibrated PowerCal?

    Ultimately, the PowerCal has peaked an interest for me that will lead to the purchase of a DFPM.

  33. Anonymous

    Great review, as always. Love the depth.

    I was looking for a inexpensive powermeter for my mt. bike and cross bike in the winter/summer. Its not clear if anything is involved in switching between bikes since it is using HR primarily if I was using the same Garmin Edge 500 with those bikes already in and each device already has a ANT+ speed sensor.

  34. I have to admit that I don’t see the main advertised use being useful at all. If HR is good enough to measure and track power, then why not just use HR, pace off of power etc etc.

    But one thing I DO see it as useful for is for data junkies at spin class or on an exercycle.

    You can bring this with you to class and get an idea of your TSS and so forth if you feel like you need power data from every workout.

  35. Hi Ray,
    Long time lurker, first time commenter.

    Regarding your comment about using this for running. I think there is more utility than you are giving it credit for; it actually makes sense that on the treadmill your power output climbed, and not just because the heat in the room caused your heart rate to increase. Running is unlike biking in that the machinery translating power from your muscles is not as consistent – form breaks down over time/distance, which should increase how much work you are doing. I’ve often thought about this while monitoring my heart rate on long runs. By the end it feels like it takes much more work to sustain a given pace, above and beyond the increase in heart rate. When I am tired and my heart rate is up, much more effort (from my perception) is needed to increase pace or go up hills than at the beginning of a run or when my heart rate is lower. I think the power estimate from PowerCal could be used as another variable to track in addition to heart rate to get a better estimate of improvements in running economy. I’m not sure you would really be able to disentangle improvements in running efficiency from fitness, but this might help.

    Random question – did you have any issues with static from wearing synthetic material shirts affect the output from PowerCal? I get that with my Garmin heart rate monitor in the beginning of some runs.

  36. Anonymous

    I’m curious about the accuracy on low RPM high torque intervals? Since your heart rate stays a lot lower and the sensor isn’t reading cadence are the power readings going to be accurate?

  37. Anonymous

    Hi everybody,

    Has someone a comparison to the calcated power from Strava?
    Its just another algorythm but powercal seems to be closer to reality

  38. Fabian C

    Ray, good stuff. So if I understand it correctly, Powercal is fairly consistent for intervals above 2-3 minutes?

    And how does the Powercal work for total energy output? I’m thinking that the Garmin gives me total calories for a ride; do you get a Kj total from Powercal that can be used when looking at losing weight and knowing energy expended?

  39. Anonymous

    I’m genuinely sorry to read that you do 80% of your workouts indoors on a trainer.

    Riding a bike is one of the greatest thrills that I know.

    • dave

      80% of workouts on a trainer almost always gives a more predictable training outcome than being out on the road. As well as a likely necessity for someone that travels a lot, it’s a very good way to get very serious bang out of every time you get on the bike.

    • Chase

      @dave, if the only reason you ride a bike is to get some perceived training-benefit for some inconsequential event then your seriously misguided….and your response just provided a textbook example of why roadies mock triathletes…

    • DC Rainmaker

      @Chase – Let’s keep things friendly. People ride and train for different reasons. No reason to bash one reason over another.

  40. Aaron

    Will this work without any cadence input at all? I’m inclined to guess it will not buy I would like a confirmation.

    • DC Rainmaker

      It works perfectly without cadence. Cadence (for better or worse) isn’t considered within the PowerCal calculations. For example, a couple days ago on the cruise ship I’m on I did a spinning class – no cadence sensor there, but still got power meter info.

  41. Sander

    Just curious, did you get to do any comparisons with Strava power estimates?

    • DC Rainmaker

      Not quite yet, it’s in my list of things to do though! I’ve actually got to go through and strip out the power info in the files so that Strava estimates instead of using that. My internet has been slow on the ship this week.

  42. gabriele

    Hi,can you explain me what is the meaning of parameters A,B,C to calibrate power cal?
    i made conconi test and the results are 183bpm for anaerobic threshold with 390w and 197bpm max with 440w.
    the powercal showed about 275w at the threshold.
    i try to change those parameters with the joule presets,and after the powercal showed more than 600w at 70bpm…
    so,how can i adjust A,B,C in the correct mode to have the correct results?

  43. Matt

    How did you find the repeatability? In the end if the numbers are skewed, but skewed consistently, you can at least make some adjustments…again, not to replace a power meter, but to get people’s feet wet into the world of power. Thanks for the work.

  44. Robert Lendvai

    Thank you for an incredibly in-depth review. While my tri coach had been encouraging me to get a power meter, I wasn’t ready to spend that kind of money. Based on your post I’ve gone ahead and purchased a PowerCal. My coach is very interested to see the data. I’ll share his thoughts over the next few weeks.

  45. Wayne

    Stupid Question Time:

    You mentioned that the power meter slowly climbed as you ran on a unchanging treadmill due to your heart rate climbing from lack of cooling.

    That got me wondering about how much it raised? The body is still doing work as it tries to cool itself, certainly nothing that contributes to your running but it’s still work.

    Could the PowerCal be a “whole body” power meter?

    Not only is it counting your legs moving but the muscle action to keep your arms from swinging, your head up, and moving fluid around the body and out the pores to keep cool? ‘Cause in the end that’s all powered by the heart, right?

    Which may make it less useful for specific action power (power to the pedals, power to the running shoe, etc…), but to me opens up a interesting new territory.

  46. Wouter

    Riding and testing for 2 months now with the powercal. ‘Calibrated’ it with a professional testing bike at our sport medical clinic for people with different FTP. Please mention below is only based on indoor testing.

    1.I think the most important thing to find out is: how much does it under or over reads for your specific situation. Below may be a good guideline for using the powercal correctly. The good news is that it over or underreads, but from my experience ALWAYS in the same way. That is good for your own situation, but you cant compare it to other riders or other powermeters. But who cares? It works perfectly for setting up your powerzones and to get a 95-98% impression of your FTP!

    2.FTP TESTING based on a 20 min max test shows and within a power profiling classification shows:

    When your are very undertrained (<cat 5 rider) the over reading can be as high as 15-20 %
    For a moderate (cat 4 rider) the over reading is between 10-12 %
    For a good (cat 3 rider) the over reading is between 5-10 %
    For a very good (cat 2 rider) the over reading is between 0-5 %

    I think this covers the user group of the powercal. My FTP is 283 (powercal) – 10% = 255 (real world). I would suggest to repeat testing every month and also to calibrate first with your powermeter of medical test bike so you with what percentage % you should decrease the powercal FTP to get a real word value.

    After all this, you can use the powercal perfectly for all P2, P3, P4 training + golden cheetah analyses. I would not recommend it for less than 2 minute interval training.

    The secret of the powercal is that is uses HRV for its accuracy.

    Good luck from Holland!

    • DC Rainmaker

      Very cool data points Wouter – thanks for sharing!

    • Wouter

      Thanks. In addition to my previous posting. More and more testing reveals that the cat 2 racer may find a under reading -3% So the new range would be : Minus 3% and plus 5% for a cat 2 racer.

      Maybe it is good to give a few examples in which the powercal does not work properly to avoid some bad reviews. In my opinion it is very useful, when you have some backgrounds of the heart system and its stressors.

      For example:

      1. When it’s extremely hot (indoor +30 degrees) or cold ( <5 degrees) don't expect it to be very accurate because of a varied heart pattern.
      2. When you are over trained, sick, or tired , don't expect too much. The ironic thing is that with a normal power meter, you will get a low average wattage and a high HF average. With the powercal, in same casus, you will get a high HF average AND a high wattage average. You may think, things are going well , but you are not! (very important point if using the PM index of Golden Cheetah or PM training peaks. The same for higher TSS, higher IF, etc.)
      3. When drinking lots of coffee before cycling, your average wattage is not reliable. Same reasons as pointed at 2.

      What i do to be sure that i will have a 'normal power cal' day is to monitor my rest HF. When it's normal (48) i train 100% by the data powercal is giving. When not: i am sceptical, but based on real facts as stated. The question is: how to use the product well and in what cases is it not reliable. When knowing this, it is really a great product.

    • Jim in Colorado

      If you have access to athletes in various age ranges, that would be very interesting to test. I am a Cat 4 on the road with top 5 results, a Cat 3 in CX, and Cat 2 in mountain biking. I found the PowerCal to be 20-30% low compared to my SRM and it would almost never show more than 350w no matter what I did. I’m over 50 and likely have a more compressed heart range that a 20-something or 30-something. After increasing the “A” parameter to 3.1 and the “C” parameter to 180, I’m getting much, much better results.

  47. dennis

    hi ray!

    first workout a few mins back, was supposed to do a 20 min test, i already paired it with my trainerroad tools, you are right the data did keep on jumping, being used to the constant power given the trainerroad(virtual) new to this as TR`s virtual power was what i have been only using. will it be fine if i use the ave power in my head unit which is just a node 1 instead of the current power? sorry if this is a dumb question but totally clueless. thanks and appreciate all the reviews!


  48. simonr

    Thx for a great website and reviews
    i have one question
    i have a garmin edge 705 and garmin speed/kadence sensor. Can i just buy the heart strap and the powercal “communicates” with this sensor? or isnt it necesary at all? i mean if it only uses HR? i get confused since there selling it with a speed sensor to?

    • DC Rainmaker

      No need for the speed/cadence sensor from them. Early on, there was a tie-in there, but it’s not really there anymore, and thus really provides no additional value when it comes to wattage readings from the PowerCal. That all said, you can continue to use your existing GSC-10 sensor with the Edge 705 and this and all will be well.

    • simonr

      so basicly i would get a new heart strap (powercals) and still get my HR and power from powercal, speed, cadence from the speed/cadence sensor (and the gps stuff from my 705)??

    • DC Rainmaker

      Essentially. Though, HR will also come from the PowerCal (two for one, HR + Power).

  49. Brian

    DC, love your reviews. I am a runner/cyclist, racer in both sports. Therefore, generally my HR values are lower on the bike during training, even during power intervals, unless I am racing. I had been using the Polar WIND wireless power meter with relative success the past 2 seasons knowing that my numbers were within +/- 5%, but recently wanted to get into the ANT+ market without blowing $1500 yet on a Cinqo. So I got the Garmin 800, Trek Duotrap for my new Madone, and got the Powercal based on your review that the numbers were basically in the ballpark. However, especially on the trainer, I notice the power numbers to be at least 100 watts low compared to my Polar, even on the high end during power intervals. I imagine that you are in considerably better shape than me so you would similarly experience lower HR values on a trainer or on the bike in general. But, your numbers seemed very close. Any thoughts on whether the calibration would be worth it? I would think that the calibration process would closer align power numbers to HR since it is comparing it to a powertap. Otherwise, it is time to save my money for the Cinqo. I want more accurate numbers than the Powercal. Any other tips for using the Powercal would be great.

    • DC Rainmaker

      Hmm, that is interesting. Calibration wouldn’t hurt. And since you have a power meter already, you could definitely do that. I’ve been trying to find the updated instructions for which numbers to input in for A/B/C. Been meaning to hit up the CycleOps guys. Sorry about that.

    • Jim in Colorado

      A good friend of mine had a Polar. We are similar height and weight. Riding side-by-side, his Polar was always showing higher numbers than my SRM. During strong efforts, it was typically 100w high — when my SRM showed 300-350w, his Polar showed 400-450w. The difference was smaller at lower wattages. And he reported some pretty crazy sprint max power numbers that FAR exceeded my SRM. He is a stronger sprinter, but the numbers his Polar reported were other-worldly.

  50. Chris

    I’m still figuring out my PowerCal/Joule combo, but an important clue to the question (“am I getting fitter?”) might be, as stated in the manual that watts is a measure “..where work is equal to force times distance.” I haven’t been able to get the Joule paired to the HR strap for “watts” as I’m pairing it while sitting at the computer, not on the bike with the wheel spinning, so there is no speed value from which to make a calculation. Similarly, if, over time, I can ride at a faster speed with the same given heart rate (increase in force), PowerCal will report more watts, and I’ll know I’m getting fitter. It won’t work for runners, unless you can figure out how to get a speed value out of the sensor while running. I think. Maybe.

  51. @Hu3ain

    While using Virtual Power on Trainer Road (TR), and simultaneously recording Powercal’s data on a separate device, I found the power readings to be way off during intervals. The climbs and drops of Powercal data are not steady. That in turn makes the cadence and gear selection just as varied to match the power demand of each interval. Surprisingly, the average power from Powercal an TR were identical for a 90-min ride.

    Powercal, like TR, are trials into training with a power meter. If that’s enticing, save up for a proper one.

  52. Jeremy H

    I have a semi-related question/problem with the PowerCal and the Garmin GSC10 (Speed/Cadence) sensor. Both units are connected to my Garmin 910.

    After I start my training session (on my trainer), when I stop pedaling I get a default cadence readout at 255. After I load my data to TrainingPeaks I have a very unattainable cadence that sometimes jumps up to 500. Obviously there’s a problem somewhere with Garmin’s interpretation of cadence after the Powercal is connected.

    Do you know the answer to fixing this problem? Do I, more simply, buy the CycleOps Speed/Cadence sensor?

    I’m more than the recreational athlete but much less than an elite. I don’t rely on power for workouts, only as a means to track semi-annual progression. So I’m ready to toss the PowerCal out the window!

    Thanks for your great blogs, I’ve been following your posts for years!

  53. Nathan

    I got this after reading the review because I wanted to see Power without spending lots of $$$. I don’t really know what I am looking at but it is fun and I am learning.

    I think the PowerCal is absolutely amazing. The watts go to 0 when I stop pedaling. Not immediately but within a couple of seconds. When you watch the watts you would swear that it is using cadence, but they say it isn’t. I would never have thought my heart rate would be able to give out such fine details about what I am doing.

    Thanks for all the reviews Ray.

  54. Eddie Maverik

    Any idea if I can manually plug in my own values from my Quarq in the A/B/C rows? What does the A/B/C represent?

  55. ismo

    A question related to the calibration process. The calibration phases are described as very easy, easy, moderate and so on. Do you happen to know the respective values given as percentage of the FTP? With those it would be much easier to calibrate the powercal: three minutes in 70%, three minutes in 80%, etc.

  56. Eric Peters


    If have been using a Powertap pro for 3 years now but only on my “summer bike”, i have purchased a Powercal Strap 2 months ago to use this during the winter. In my case for absolute watt numbers this device makes no sense at all.
    However I’m actually not interested in absolute watts but I’m interested in a tool that improves my training. I have been using WKO+ and specifically the perfromance manager chart. As you know this chart is based on TSS which is based on the balance between actual power vs FTP. I suspect that when you establish the FTP using Powercal measurments than the TSS calculated (and as a result the PMC chart) will be pretty accurate.

  57. chakor

    Interesting stuff. So understanding the benefits of having estimates of power output while on the road…from a post ride perspective… how would you rate the quality of information produced by the Powercal to Strava’s power curve algorithm?

  58. Geo

    Is it waterproof? Can I wear under the wetsuit to be ready for the bike and run after the swim in a triathlon?

    • DC Rainmaker

      Yes, no problem using under a wetsuit.

    • Nicole

      Based on your comment here I used my PowerCal for a triathlon this last weekend. I got wonky HR and power readings for the first 5 miles on the bike. The CycleOps website does say that this is NOT waterproof. Is it really ok for a triathlon swim? Thanks.

    • That’s more likely to be something like water pooling under the strap, as odd as that sounds. I see it occasionally on a variety of straps. Somewhat rare though, and usually just slightly adjusting the strap will instantly clear it.

  59. Adrian

    In general where the weather hovers around 30-35 degrees celcius, will the Powercal still works? Or the pattern will be more varied? Due to the high temp I’m located at, my HR always shows around 160-170 on average, so will there use that as a baseline for calculation purposes, and determining any rate of change from the average to determine Power.

    • DC Rainmaker

      Yes, temperature has no bearing on it. It’s primarily change in HR, and rate of change that the unit is focused on.

  60. Brent

    Thanks for the review. Due to my remote work location and number of bikes i cannot use a powermeter for 2/3rds of my rides so on the basis of this review i purchased a powercal to try and bridge the gap. Somewhat for intervals but also for TSS. Before it arrived i assumed that the no calibration thing was a marketing decision rather than a scientific requirement. And i was correct, at stock calibration my measured power was 50% greater than powercal. I am am an average masters racer but larger than average (90kg) with a fairly high FTP.
    After calibration it seems within 5% for any length of time drawing closer the more warmed up i am.
    There are some issues with the calibration process though that make it hard.
    1. Cycleops have removed virtually any mention of it and the only instructions i can find are your review.
    2. You really need to do it on a trainer (learnt this the hard way) which if you have an inbuilt dislike of the trainer like me is hard.
    3. My up to date poweragent always calculates “responsiveness” as zero (this is “C” when you transfer it to the powercal calibration). So i had to guess a number and i chose as close to 150 as i could get as this was the original. 150 exact is a bit of a problem as the slider is to picky and i could not get exact 150. Some explanation from the manufacturer would probably help. Note that without a value the power reading essentially is just tracking your heart rate.

    So in summary. It can be a useful gadget but the calibration process is difficult on purpose with no help. I would recommend anybody with a powercal who can access an actual power meter to perform the calibration. I would like cycleops to provide a calculation for “C” or at least a discussion to allow us to make an informed guess.

    • Jim in Colorado

      My experience is very similar to yours – the PowerCal was 20-30% low, the only info I could find was in Ray’s review, calibrating is very challenging when the user has to figure out what effect changing A, B, and C has. Mine is now pretty close to the SRM on my other bike based on A: 3.1, B: -200, and C: 180. I think the calibration values are affected by your fitness because it affects watts per heartbeat increase (I’m a Cat 4 road / Cat 3 CX / Cat 2 mountain biker) and age because the heart beat range compresses as you get older (I’m over 50). The values that improved the accuracy of my PowerCal may not work for others.

  61. Adz

    Just gotten my Cycleops PowerCal. Anyone experiencing major spike issue in the heart rate? I tried using Garmin and CycleOps HRM Strap, and applied electrode gel, still having spikes. Temperature is around 33 degrees with high humidity. So should not be static.

    Maybe this image might help.. link to oi48.tinypic.com

    • DC Rainmaker

      Eek, that’s weird. And, the upwards spikes don’t even match normal spiking issues. I’d ring up CycleOps support and have them swap the strap out for you. Their support group is rock solid and should get you fixed up in a few minutes.

    • Sever

      Yes. I have the same problem with these 2-3 seconds spikes. I think that they appear from the sweat because in my workouts I don’t have any at the begining, just after an hour or so.
      I’m thinking to buy another hr strap. Maybe the one from Polar but I don’t know if it’s compatible.

    • Kyle

      I’ve been using the powercal for about 9-10 months. Lately, I’ve also experienced unusual heart rate spikes. Picture here: link to tinypic.com

      I expect spikes at the beginning of the workout, but the spikes towards the end are weird. I was holding a steady pace on flat pavement. Think this is a connectivity issue?

    • Yeah, small spikes like that definitely looks like a typical strap issue. See this as a starting point: link to dcrainmaker.com

    • I too got those spike issues today. But then noticed the transmitter was upside down (didn’t think this would matter). After turning the hr strap around so transmitter was correct way, it worked far better.

      link to pbs.twimg.com

      First part, transmitter upside down. Stopped to make sure strap was wet. Then turned strap over.

    • Steve S

      Wow, that’s pretty wild. I just assumed that any HRM could be used in any direction (well, any of the 2 directions, I guess). I don’t think Powertap has any guidelines about “right way up” for this. I’m going to try the same test soon and see if I get the same jagged vs smooth results.

  62. Aleksander


    I am considering on buying powerCAL. But I am concerned if it can be used for what I would like to use it ;)

    I am thinking on using it for two things, first 5 x 5min intervals on a short hill (with constant power) and for pacing myself on longer climbs (from 5km/450m to 15km/900m). With both of these trainings to keep up constant power, you will need higher HR with time (each interval), for example at the start of a long climb to pedal 300W ones HR would be 175bpm, and after 30min of climb, to still put out 300W ones HR would be over 180bpm.

    How does powerCAL deal with such riding, can I pace myself on longer climbs with it?


  63. Rafael Ramos

    Well, just got a powercal (my older garmin HR montior died) and powercal was just $30 more in Canada, so it’s nice for the added feature for when I had a rented bike, or go for a MTB ride without a powermeter.
    I was surprised actually at how close it was for average on >5 minute efforts against my quarq, but still would like to have it “fine tuned”.

    Has anyone had success connecting the PoweAgent using the Garmin stick, with windows 8 or a Mac? The stick is working fine (works fine downloading workouts and with trainerroad). But there is no way I can get it to work to configure the powercal, it does not find the powercal.

    Has anyone experienced similar?

    • Brent

      I connected using the suunto stick that this website recommended. Make sure you activate it first by either putting it on or rubbing the HRM strap pads with the transmitter connected to the strap. Can’t stress enough how important it is to use a trainer and try to make it as close to the instructions DCR has above. Good luck.

    • ToddMcLean


      Did you have any luck figuring out the calibration?

      I am having the same issue. Ride analysis is good. New values set in my user profile just fine. But when I select the values and try to save to the PCal, it just sits there thinking forever, eventually giving me a Java error message. I am using the Suunto stick, and the strap is active. Computer is a Macbook running 10.6.8.

      Frustrating, as the PCal numbers are 40% higher than my PowerTap.

  64. grifo

    I’m not sure if I am misunderstanding the calibration instructions, but does one record the ramp test with both the powercal and another power meter? Or do you simply use the direct force tool to record the test and then use data from that to write back settings to the powercal?

  65. Rafael Ramos

    You do the ramp test with a head unit recording power from a direct force powermeter and HR (I used quarq and an edge 500). Open that workout file on Power Agent (ok until here), the PowerAgent analyzes the file (ok) and then defines new coefficients (ok) to be sent to re-configure the Powercal (where it fails).
    Sending the coefficients is the part it is failing . It does not seem to reach the powercal for some reason. Garmin Ant+ agent is closed, no other software or service is using the usb ant+ stick, ant the powercal is awake (i had it on and it is streaming HR data to the Garmin Edge).

  66. Brent

    It sounds as if the drivers for the ant+ stick are not working correctly. Can you verify it with another device. Try different usb ports.

  67. Paul Gagnon

    Will it work with a Forerunner 305 fro Garmin?

    • DC Rainmaker

      No, the FR305 doesn’t support power meters.

      It does however support the heart rate strap piece of it though, so that portion will work (but in that case, you might as well save $60 and just go with a regular HR strap).

  68. Paul Gagnon

    Thank you looks like I might have to go for the more expensive package.

  69. Thomas

    RE: Powercal and latest Garmin Soft Strap

    I’m having trouble getting the Powercal to work and pick up actual readings on my 910xt when using the Powercal unit with the Garmin Soft Strap (newest version).

    Any suggestions?

    • DC Rainmaker

      Is it not picking up anything, or just wonky readings?

    • Thomas

      It’s literally not picking anything up – really strange. I played around a bit and “flipped” the Powercal so it’s “upside-down” when connected to the strap – no success =(

      Everything looks to be attached pretty solid – it detects the HR monitor and the Powercal with the correct serial # but the readings don’t register.

      I wish it were just wonky readings =(

  70. Brent

    For those looking at spare / replacement straps.
    Powercal with Polar soft strap. I have used the powercal successfully with the garmin soft strap. The powercal seems incompatible with the polar strap however (even though the garmin transmitter is compatible). There is something slightly different about the holes that the transmitter plugs into on the polar strap. The powercal transmitter pops straight out.

    • Thomas

      Quick update on my non-working Garmin Soft Strap [when using Powercal]:

      I used/took my lady’s Garmin Soft Strap and tested the Powercal combo…and it worked =(

      I then tried to get my Garmin transmitter and Soft Strap combo to start working again and it doesn’t work anymore =( I even tried using the electrode gel and it keeps cutting out and giving me readings of “0”

      Any suggestions?

    • Brent

      This sounds like a classic case of broken garmin soft strap. I have broken one myself. Could pair the device but would get either no signal or very briefly a dodgy signal. The electrical connections inside the strap are i presume not very sturdy. As you say taking the transmitter to another strap it works good. They are not to much to replace but i think not quite sturdy enough for purpose.

    • Thomas

      *Update/Workaround for the AWESOME Polar strap and PowerCal Combo*

      You were right when you said the Polar strap didn’t hold the PowerCal – it does just pop right out. Upon further messing around – looked like the rubber grommets around the metal pieces that snap the PowerCal were too big to hold the PowerCal’s shallow inserts.

      I trimmed the rubber pieces down a bit with nail clippers and the PowerCal fits perfectly and work perfectly as well. [Although I have to be honest – I don’t use the PowerCal as much anymore as the purchase of the PowerCal “gateway drugged me” into getting a PowerTap =P]

      Hope this helps for some people out there!

  71. Berndt Hanns


    I’ve recently bought a home power trainer and a PowerCal for a young junior cyclist to train with.

    Using the theory that the most gain can be made on the home trainer, it is becoming an integral part of the training program and although we are still figuring out the best ways to use power based training its starting to show marked improvements, particularly with hill efforts and IRTT times.

    The PowerCal seemed to be a good way to learn how to train with a power based tool. I’ve seen a number of parents splash out on P2Max, Quark and even SRM PowerMeters, all which look really good on the bike (and at the coffee shop) but, truth be known, a 14 or 15 year old boy or girl is not going to get the best vaule out it – some even admit to not knowing how to use it properly. Not the return on investment that a lot of us want! Sometimes I think parents like to brag about what their kids are using more than the athelete themselves.

    So, back to the PowerCal, the thought was/is to get the young athelete starting to use the power numbers during their training and possibly even racing. Yes, its got quite a few short comings, but the price, not significantly more than a HR strap, makes it an attractive option to start using power data.

    Which leads me to my question! Given its very spikey and not particularly much use for sprint efforts, what I’d ideally like (hope) it can be used for is sustained efforts up hill and against the clock. The head unit I’m using is a Garmin510, so its got a range of display options – as a learing exercices and hopefully some race benefit, what is the best display to put infront of a young athlete using a PowerCal.

    Am I best simply to put instant power there or one of the smoothed options and if so, which option? In the end, the read out needs to give the rider some level of usable information so they can adjust their effort to suit.

    Any thoughts on this and as an overall first power training tool?

  72. Ty

    Can it be worn in a non-wetsuit swim?

    • Yes, no problems at all being word under a wetsuit, or under a tri-suit. Water immersion isn’t an issue. Note that in neither situation will it broadcast HR while underwater (well, technically it broadcasts HR all the time, it’s just that the ANT+ signal doesn’t go anywhere underwater beyond about 1 inch).

  73. Michael Zeidan

    Thanks for a great review! It certainly peeked my interest as I cannot afford a Powermeter yet but would love to get power data.
    However – my main interest would be to use this as a Pacing device for IronMan racing, as my heart rate seems to go all over the place during racing. I’m not sure whether that’s due to nerves, heat, hydration and nutrition, heart rate drift due to lack of fittness or whatever. I know that you said that this tool is not marketed for race pacing use, and my intuition is that since this tool goes off heart rate then all of the abovementioned heart rate issues will be transferred into their Power calculations…

    So my question is this: Given all of the above HR-related race pacing issues, would there be any advantage to race-pacing using this tool over race-pacing using a HR monitor?

    If the answer is Yes – i’ll buy one, else I wont…

    Thanks again!


    • Hi Mike-

      For Ironman racing, it probably would help from a quantifying it standpoint. Obviously, since it’s built as an extension to the HR side, there’s some correlation there. But it may help better put things into perspective over the course of a race from out output side, rather than HR (which is more of an ‘input’ in this particular equation.

  74. Tom

    Does anybody know how the cal burn this would calculate (from average power and weight), compares to other calculations? For instance, the Garmin 705 calculates calories, but in my opinion and in that of many who have posted on Garmin forums, the value seems way too high. So, i wonder if i use this to get power, and convert to calories, how it would compare to what the Garmin itself calculates.

    Or also…if you know of a recommended web site or software to upload a track and get a calorie calculation, please let me know.

    Thank you! Tom

    • The PowerCal isn’t transmitting calories, just power. But, you could use kilojoules (a function of power) to get a better handle on calories, which the PowerCal would help with.

    • Tom

      Ray, thanks much! I guess to be clear, what i’d like is that, say, you took the power computed by cycleops, and converted it to calories, how does that compare to what the Garmin spits out as calories? Again, seems to me (and many who post to the Garmin board) that Garmin is way high on its calorie calculation.

      So, i guess its actually kind of a complex question without a quick, simple answer.

      But, if anybody has ever made that calculation on the same ride, i’d love to hear the comparison!

      Thanks! Tom.

    • The calorie calculations vary by different Garmin devices, and in the case of the Edge 705, it’s one of the older units from a calorie calculation standpoint. If you look at the charts here, you’ll see that for the most part, the Edge 705 is basically just doing simple speed/distance calcs – which are largely useless. link to dcrainmaker.com

      I haven’t taken a look at how the kilojoules from the PowerCal compared to that of the calorie calculations natively

  75. Francisco

    hi DC,
    I’m a age group triathlete newbie with power tools and my question is… I can swim with powercal??? and that the box says not to submerge?? greetings from Venezuela

  76. michazeidan

    Ray – many thanks for your comments, I think I’ll get the thing and try it out…thanks again! mike

  77. Andres Di

    I have been an avid reader of all your products.
    Question: I have a powercal and garmin 910tx. After last update, I have a cadence readout of 255 continuously. I have been told, it could be either of the items.
    Before update, everything was working perfect. How do I fix this?
    Thank you.

    • 255 is meant to indicate cadence not available in the ANT+ power profile. This is what I would expect the Powercal to set. The 910tx should ignore the cadence data if it is 255 it should use an alternate source if available or set the cadence to 0.

  78. Ray Smith

    I have owned the PowerCal now for the past 6 months. I used it to test my FTP, and coordinated my training using Carmichaels Time Crunch Cyclist (book). Have read many of the post, I can understand why many non users have questions or don’t understand how this could work. I put all my training workouts on Strava and the power meter opens up many new pages and analysis. For example, I now have a fitness and fatigue score, which computes my “form”. My FTP has improved using the interval workouts by about 15%. Note that many of the posters can’t understand how this could be, especially as my HR has remained fairly constant. None of us understand the algorithm being used by the Powercal, however I can tell you that I continue to be shocked with how responsive it is and how directionally correct it is. If you use it to establish your FTP, then train around this number, you won’t believe how good of a tool this is. I have no plan to purchase a more expensive version, not only is it cheaper, it weighs less, and is transportable from bike to bike.

    • MichaelZ

      Ray — I’m also relatively satisfied with my Powercal although it does have the drawback of generating a lot of spurious power values. So I’m curious what time averaging do you use to display power while riding?

    • Tim

      Ray Smith and MikeM,

      Are you guys using a 30 second power smoothing/averaging that Garmin has during your training and especially with respect to the Time Crunched training? I’m surprised to not see more discussion on this since short periods of time appear to not be very useful. Ray Maker’s YouTube video (found elsewhere) of the display was very informative and shows what the results look like with the instantaneous, 3sec and 30sec smoothing.

    • Raphael

      Hi Tim,

      I use the 30s average. It is best for me. There is too much variations and spike with the 3s and the 10s.


  79. Ray Smith

    MichaelZ—I load my workout on to the Garmin (500), if I am doing steady state intervals (3×10), with 5 min rest between, the Garmin tell me when I am in the proper range for my power zone. It works great for all power zones, EM, SS, PI. This training is very intense and the Powercal works near perfect as long as you did the FTP test properly. My FTP test called for two 10 min intervals at a max power that can be sustained for 10 min, twice with 5 min rest between. Otherwise, I like the 10 sec average the best, but do not use it for training.

  80. MikeM

    Has anyone tried the Powercal on Kinomap or Virtual Trainer? Wondering how it would perform as would be good to use Kinomap on my iPad mini on the exercise bike in the gym.

  81. JAC

    Hello. Great reviews!Quick question, does viiiva work with android smartphones and apps? Using a S4 ver 4.2.2 right now. Also will it transmit to Android based Recon JET glasses(+Bluetooth 4.0 -Bluetooth Smart-)?


  82. Dinos Chryssochoou

    Ray, being in your father’s type of audience I found the review extremely helpful. Tried to order the strap from Clever training but they didn’t have any left. Eventually I ordered the cheapest one I could get that ships to Athens. Sorry I’m not contributing to the site man, next time for sure.

    • Thanks for the (attempted) support Dinos!

      I see what went wrong. The product ID that I had in my database had been changed, and as a result you got an error when clicking. You logically went to search, and came back with the first result – which happens to be the Bluetooth Smart variant which isn’t in stock, as opposed to the ANT+ version.

      In any event, I appreciate you letting me know! I’ve gone through and fixed all that – thus for others, the world should be back in place now.


  83. MikeM

    I contacted Kinomap support late Friday evening to ask about using the Powercal with Kinomap. Firstly, I would like to commend Kinomap – in particular Laurent – for their fast response. That aside Kinomap have not tried the Powercal with their system and I expressed my concern that the noisy signal might be a problem. Laurent confirmed that there was no filtering/averaging of power data but that the video has some built in latency – although that may not be enough to give a reasonably smooth response with the Powercal. Laurent is meeting CycleOps at Interbike next week and will try and test the Powercal with Kinomap.

    I travel a lot and it would be a nice lightweight virtual training setup if I could just go with a Powercal and iPad Mini using spinning bikes in hotel gyms for example.

    I await Laurent’s test with great interest!

  84. Hey Ray,

    If I have the Garmin Cadence/Speed Sensor already installed would I still need to get the PowerCal Speed Sensor? I’m guessing they don’t talk to each other huh?

  85. and…. does the PowerCal Speed sensor detect Cadence? I’m seeing things online that says it does either speed or cadence but not both. That would be a disadvantage on my bike trainer.

  86. Ray Smith

    Daren, No need for the speed sensor. I did not buy it and everything works just fine. Have no comment on cadence since I use the sensor I already had on my bike. The PowerCal serves two purposes for me 1) HR monitor and 2) Power meter. Both feed into the Garmin no worries

  87. Double A Ron

    Thanks DC for the in depth review. I know some folks may snicker, but I just got my first taste of power training at a new gym here locally in Plymouth, MA (Live Life Believe). They have a whole room of CycleOps 300 pro indoor cycles with Powertaps. I’m an avid outdoor cyclist that doesn’t necessarily need a $2000 power meter (that doesn’t keep it from being on the wish list though). It seems like this may be a fair alternative – meaning that you probably get what you pay for? I enjoy the data I get at the gym and my fitness is getting better using that data. I also just got into strava (I hear the snickers) and I like the fact that i can add this data to my uploads as well as let me upload indoor training data. Which leads me to my main question:

    1. Do you think it would be worth purchasing for a first time power meter user to use at home and out on the roads or should I just save my pennies for the real thing? Keeping in mind that when I say I am an “avid” rider, means I have a Specialized Venge, ride the Pan mass Challenge (200 mile fund raiser to fight cancer), and ride the Spring training crits (I am finishing in the back and trying to change that).



    • Brent

      How much money you wish to spend is of course up to yourself. I have bith a powertap and a powercal. I personally use the powercal on rides i cannot use the powertap on to get a sense of how hard my total effort was. Using the powercal for shorter intervals (less than a minute at least) does not make a lot of sense. It can be used reasonably well for longer efforts.
      To get much use out of it compared to you powertap sessions you would need to calibrate it against the powertap which may be easy to do if you are using or can use a computer with downloadable data. You need to complete the calibration as accurately as you can with the instructions ray provides above. And you will need to redo the calibration if your FTP is changing. Because any differences in FTP the powercal by itself would show are simply changes in HR response. Any efforts at the same HR will produce the same power on the powercal. ie if you go for 20 minutes at 180 BPM it will show the same result even if your actual power has increased 50% over a period of time.
      My poweragent software did not give me a value for variable C. Simply use what the powercal came with which i think was 150.

  88. Rowlarry

    Hi Ray, fellow posters

    Can I just say that I have spent many hours perusing the shiny new fitness tech in your website, and I’d like to thank you for the time and dedication spent in doing the reviews in your own unique style.

    I have the opportunity to pick up a Motoactv cheaply to replace my aging FR305, and I was wondering whether the PowerCal would work with this and provide HR and Power data to it? I can’t find the answer anywhere.

    Many thanks, Larry

    • Yes, it’ll transmit it to it, the PowerCal simply acts as both a HR strap and a power meter, which the Motoactv support.

    • Brent

      I have both these items. The answer is that the motoactv will pick up the HR or the power. Not both at the same time.
      Once you have paired it with the one it will not pair with the second. This presumably is due to the powercal using the same ANt+ ID for both.

  89. Adam R

    For reasons I cannot work out, PowerCal calibration in PowerAgent worked in VMWare running Windows 7, but not natively on my Mac. The Mac app failed (immediately, and apparently without searching) to find the PowerCal. I assume it was not loading the Ant+ stick driver properly, but I have no way to verify that. Other apps (such as trainer road) can use the Ant+ stick just fine.

  90. Steve S

    Great reviews. I don’t have a head unit, not even a cycling computer. I look at screens all day and don’t want to when I ride, on a variety of bikes and trainers. That being said, I do record my rides/workouts with mapmyride or strava on my iPhone 4S that I hide away in my back pocket. Can this device be effectively used and/or communicate with only an appropriate phone app such as these apps, or do I have to also use a head unit? If my goal is to simply have the phone and phone apps be my hidden computer, recording data as I exercise, are there any other devices that can do both HR and some sort of power calculation, or other apps to consider? Thanks.

    • Yup, you’ve got two options. The first is to pickup the Bluetooth Smart version of the PowerCal, and the second is to pickup the ANT+ version and then get an adapter (Wahoo Fitness iPhone ANT+ adapter).

      Given you’ve got no other devices, it simply makes sense to pickup the BLE version. You can then use either the CycleOps app or the Wahoo App to connect to it and record the data for later analysis and uploading to dozens of different sites (Strava, Training Peaks, Garmin Connect, etc…).

  91. Steve S

    Ah, thanks, there’s a bluetooth version, I see it now. Assume it has the same functions of the ANT+ version (and probably not worth a separate review)? Can this newer BLE version connect directly with MapMyRide iPhone App, or Strava, etc, of do I need to use the PowerTap app to record, or at least to bridge data to the other apps, all with just the phone, or do you expect I’m going to have to move around/upload some recorded data in order to view it in my system of choice? Thx again.

    • Correct, identical except just BLE. It can connect to some apps, such as the Wahoo Fitness app. I don’t know about the Strava or MapMyRide App (though Wahoo Fitness uploads to both and many more).

    • Steve S

      Thanks and good to know. Will try it out and report back on what I find. One additional question – if a separate wrist-based device is in my future, would the ANT or BT powercal version be a better choice?

    • Today, it’s definitely ANT+, since there are no BLE wrist-based units currently on the market (that can connect to BLE Bluetooth Sensors or BLE SPD/CAD sensors). In fact, for that matter, BLE HR straps either.

    • Steve S

      Hmmm…not that it’s a true watch, but I wonder if the polar loop would pick up any transmission from the powercal Bluetooth. BLE and Bluetooth smart are the same protocol, right?

    • I’m travelling and don’t have both the Loop and BLE Powercal with me, but in theory, the Loop will pick it up just fine for the HR portion (since both adhere to the BLE HR Profile spec).

  92. Colin Carroll

    I Have used Trainer Road for the first time today and I found a big difference between the TR numbers and and powercal numbers. I was doing the 8min ftp test and my numbers calculated on TR were an FTP of 137 watts and a LTHR of 160.
    However my power average on powercal was 212watts for the 60min session. I am using a cycleops mag trainer set to level 3. I have read that people are getting comparible results between TR and powercal and I was wondering what others have found?
    Could I be one of those individuals who are outside of the powercal profile.
    BTW. Great site Ray. Chapeau.

    • Brent

      If you can grab hold of a power meter of some kind and do a calibration as ray describes in the text you should be able to get reasonable numbers from the powercal. You need to do it accurately as possible as one interval for all 5 power steps (the poweragent software only looks at one completed interval). You will need to guess the 3rd parameter which the software always gave me as zero for the calibration). The original number for the 3rd parameter was 150 i recall. Although i don’t know your ability or size 137 w does seem a low number.

    • Colin Carroll

      Just been reviewing my Trainer Road data and my actual FTP was 200 watts back in January. I was reading the NP figure DOH!
      However as my fitness has started to improve the Trainer Road and Powercal outputs have started to synchronize with one another.
      I love this technology.

  93. Larry

    I got a PowerCal Bluetooth Smart and tried to use it with my iPhone 5 and Strava v3.8.1 (1449) and could not get it to work. I could connect to either HR or Power but not both at the same time. I also tried MapMyRide 5.1 and got the same exact situation. I’ve contacted both PowerCal and they could not help. I sent Strava a email and have not heard from them. Since I emailed them several weeks ago, my guess is I will never hear from them.

    Any suggestions or comments?

    • Steve S

      Larry – I just got mine yesterday and experienced the same thing. I called PowerCal/cycleops yesterday afternoon and they told me that yes, b/c this device sends both power and HR data in one data stream, apps like Strava and Map My Ride will only pick up one part of that data stream, and that’s the HR data (not power). It won’t pick up power because those apps expect that data to be sent in a separate data stream. They said they are working with those major app players to get both sets of data to display simultaneously (picking both up from one transmission stream). That would be an update to those apps with ability to differentiate data within the single stream.

      The “work-around” I’ve found is to 1) use the free PowerTap app, which WILL pick up both streams (it’s the only app that will display both). Ideally, you can connect the PowerTap app to your strava/MMR/other accounts for data transfer, but the “Connect” authorization fails. When I spoke with them about this yesterday, they said I had discovered an authorization bug that they would fix sometime soon. I also had issues simply creating a clever training account, which the PowerTap app can sync with, and I believe you can import/export data among those services in a variety of ways.

      For me, all my historical data is in Map My Ride (and I’d like to continue to use it), so my solution for now is to have both MMR and PowerTap ads recording simultaneously so that I get all data. Hopefully at some point, power will show up natively in MMR and/or the connection authentication will be fixed between the PowerTap app and MMR.

      Connection and data stream limitations aside, I found the HR and power data coming from this device to be clear and solid, and within the boundaries of what I’d expect for a big-picture view of how power relates to HR and output (for a 1 hour moderate ride, 163 average watts, 476 max watts, 194 normalized power, 330 watts for 30sec peak power). Not expecting detailed instant data, so I’m hoping over time, I’ll see some trends in those overall power averages.

    • Brent

      The motoactv is the same with the ant+ version. Because the ID # is the same for both hr and power it will only do one at a time. Whichever is the first to pair it will recognize. So as you have probably worked out pair the power first and your okay. It is probably just a software thing though for the phone. My garmin and suunto devices will pick up both,
      i had a mio 105 unit and it would pick up both until a firmware “upgrade” at which point it was only one at a time. (again this was the ant+ version but a similar problem). When i wrote a lengthy note to mio support they reported to me that the mio 105 does not connect with power meters showing poor knowledge of their products and also the fact that the support did not read my lengthy email description.

  94. Forrest

    Has anyone had luck using the Bluetooth version of PowerCal for power on any app other than the PowerTap app? I couldn’t even get power to register in the Wahoo Fitness app.

  95. Steve S

    @Forrest – Cust support says that the ONLY app that will read power is the PowerTap app, which is slated to be updated soon by the way. Unfortunately, all of their API authorizations to other services to sync data automatically (Strava, MMR, etc) are broken, so I’ve probably had several dozen emails back and forth with them about that issue. However, once that’s fixed, the power data should sync up to the other services (export/import works now if needed). It’s just that the other apps don’t read the power from the powercal strap natively. They are also working with the other companies’ apps to help update code to recognize the power data from the powercal strap, eventually.

  96. Phillip

    Hi, I just bought a PowerCal, it arrived with scant instructions, and nothing to explain the cadence/speed select switch inside the battery compartment. It all works ok, but any info about that switch ( why, which setting etc ) would be much appreciated. The only real info I could find is this vid link to youtu.be which also shows the unit being reversed with each setting. Thanks :-)

  97. Tom T

    Hi, hopefully someone can help me I’m trying to do the calibration but not having much success. I’ve done the ramp test and gone through the instructions in the article re calibration. when i zoom into the ramp test and select configure powercal the next window shows me the complete workout not the zoomed in segment. I can’t figure it out what I’m doing wrong its driving me mad! If someone can help I’d appreciate it.
    Thanks :)

    • brent

      you need to do An interval on the bike computer on the bike not just zoom in. so start your ride and warm up and when ready use the bike computer to start the interval and then finish the interval when done. alternative would be to use your file you already have and make an interval on your software but i cannot tell you if the powertap software does that. you may need to make up a value for C. i used 150 which is what the original cap was. i went from 30 % or more under my actual power to within 0 – 5 % except for every short intervals.

    • Tom T

      Hi Brent, thanks for the info. I think I’ll just have to re-do the ramp test. The file I have has about 10mins of a warm-up preamble to it and I’ve tried to crop the file with tcx converter but it makes a balls of the data set. I think you’re right I’ll give it another go tonight and just start stop the edge for the interval. Your results from calibration are encouraging, I’m just looking to get it a bit more consistent in terms of numbers at the moment it’s not consistent it either reads about right or way under and then jumps back up very erratic. Actual accuracy to a direct force pm I’m not worried about. Thanks again for the reply much appreciated.

  98. Ray Smith

    @ Tom T, not sure that your intent to calibrate the Cycleops will get you where you want to be even if you are successful. I have been using mine for the past year and it is clearly understating my power. I have other friends where it overstates their power. It is very hard to ride with power showing on our computer for most any of the meters due to the veritably )read Rays study on this and others. If you use it to set your FTP then train around the FTP score you got from your Cycleops it will give you the same (almost exact) benefits you would get from the most expensive meter. I race and use mine to determine my stress load for each ride, my Fatigue level, my Fitness level and my Form. These are all mathematically derived from using the PM each time you ride. If you are looking to do more with yours then you have the wrong equipment. At the present, I see no reason to upgrade as I get just what I need even though the calibration is off.

    • Tom T

      Hi Ray, thanks for the reply. I’m looking to calibrate as the numbers I’m getting are extremely erratic. I’m not worried if it’s not accurate just as long as it’s consistent. All I’m aiming to do is get it a bit more consistent in terms of numbers at the moment. It far from consistent at the moment it either reads about right or way under and then jumps back up very erratic. Actual accuracy to a direct force pm I’m not worried about. Thanks again for the reply much appreciated.

  99. brent

    don’t get to hung-up about pure consistency. all pm go up and down a bit which is why people often set there computers to show 3 second and 10 second averages rather than instant readings. also like a hrm if the hr readings are erratic due to poor connection which especially happens before you work up a sweat than the results will be poor. good contact is required.

  100. Dan Gay

    Great review! I took the dive and bought one and have found the results to be useful for my purposes. I use a Cateye Stealth 50 which unfortunately won’t show average power, but post work out data is useful. A question I was pondering though would be how this device can differentiate power output from someone with an FTP of say 250 as compared to me with an FTP of about 200? If resting HR is the same and HR responses are similar, how can it reflect, on average, those potential differences?

  101. José

    Hello, can it be used just as a HR with the FR70 or the suunto m6?


  102. José

    And would it tell me the power on de FR70? Or just the heart rate?

    Thnxs again

  103. Juan

    Thanks Ray for all your time, effort and professionalism, posting these unbiased tech reviews in your site. They’re amazing.

    Just to share an issue I have with those avid riders out there with a CycleOps Joule GPS and PowerCal combo. I’ve got mine yesterday, unpacked the boxes like a kid on Christmas day, installed PowerAgent, and spent the whole afternoon trying to set this up. I bought the Joule GPS head unit (firmware 19.076) and the PowerCal strap 7150, no speed sensor. All ANT +.

    Here is my problem: I can’t get the PowerCal to be paired with the Joule head unit as a power meter. I initially used the option ‘Pair All’ and the Joule finds the PowerCal as a HeartRate Strap unit, it prompts to accept a HR sensor ID and starts capturing my HR beats. Fine, but I haven’t found how to get the PowerCal added as a power meter unit.

    Trying to troubleshoot the issue, I did remove the HR sensor id from the setup and manually tried to register the PowerCal strap as a Power meter, using the same sensor id it was picked up when initially the Joule head unit recognized it as HR strap. No luck here either, as the Joule couldn’t find any power meter device under that sensor id. So, I went back to the setup, and either manually, or using the ‘Pair All’ option, Joule GPS always picks up the PowerCal as a HR unit only.

    I changed the CR2032 battery, reset the whole thing and read the user guide twice (yes.. twice !!). Any ideas what I’m doing wrong here?. I can’t think of a defective PowerCal strap, as the HR works like a charm !!!. I’m planning to borrow a friend’s Garmin 510 and test the pairing process again, trying to rule out any hardware issues with the PowerCal. We’ll see…

    • Juan

      CycleOps tech support guys provided some feedback that helped with the PowerCal issue (reporting Power as ‘0’s). They suggested me a ‘hard reset’ of the strap by removing the CR2032 battery and put it back with the wrong polarity (‘+’ sign face down) and leave it for 20 sec. Then remove the battery and put it back as stated by the user guide (positive ‘+’ side face up). I did it for 20 sec as initially stated by the CycleOps, but it didn’t work, as my power reading were still reporting ‘0’s, so I tried again for 10 min now and it did finally the trick.. power readings came up from the PowerCal once I got into the bike…

  104. Just want to post and make people aware, I’ve had my Powercal since February, and used it 3-5 times per week since.

    Yesterday the headunit no longer found the powercal (heart rate monitor).

    Change of battery didn’t work
    Pairing with a different garmin didn’t work

    Tried a garmin transmitter on the Powercal band, and the headunit found the monitor.

    Conclusion, Powercal transmitter has given up, so it is going back for a refund.

    (ps, also tried the hard reset’ mentioned above to no avail)

    • I’d ring up CycleOps/PowerTap. Probably the easiest folks in the industry to work with customer service wise. I’m sure they’ll likely just shoot you out a new unit no questions asked…

  105. Mr Nofish

    Ray, if I can take advantage of your considerable patience, expertise and outstanding dedication to the site, there is a question I’d like to ask you:

    Short premise: I see the value in training with power, and ideally I would buy a DFPM but my price bracket would be closer to half or (preferably) less what Stages is retailing for now, which I assume is still years away. I am aware of the PowerCal’s limitations, and my thought is I could keep training with heart rate alone, but there’s probably a little extra value in the PowerCal.

    So, should I pull the trigger now on the PowerCal, or there’s anything else on the horizon that might become available in the next 6 months (give or take) and fit my profile better?

    A Yes/No reply would be OK and if you’d rather send an email than reply here, that would be great. Thanks for your time!

  106. knightof1

    hi ray. u experience various products n write excellent articles! im so envied!
    i hav been using powercal for a year, but i started to pay attention to power training not long before. when i review my data, i found that the relations between hr n power(in terms of avg, >30min) have not really changed. however, i am 100% certain that i have made great progress during the last year(after all i just began riding then, n i go much faster in the same tt course). anyway, if powercal could not describe my change day-by-day, it could not be a good product. for instance, i recorded 160bpm-248w in january and exactly the same number in may, both in a duration of 20min. another issue is that it is impossible for me to squeeze 248 watts under 160bpm. my assumption is that these hr-watt correspondence are collected from a database given by caucasians. as u see, i am chinese.

    is it worth a calibration? powertap is easily accessible for me now. im planning to purchase a new version of p2m. plz stop me if u hav strong reasons!!

    thank u so much!

    • brent

      Yes it will give you the same results without being constantly calibrated. It is worth doing especially if you get a power meter and intend to keep using the powercal on rides. After you start using another power meter you may notice completely different power to the powercal. A good calibration will bring the powercal back in the ball park. I use my power meters when I have them and the powercal for all other rides when the power meter is not available mostly so I can get a TSS rating. If you do not use it in conjunction with another power meter then regular calibrations may give you a better handle on any changes.
      Note that if you have a good steady and long climb (30 mins?) you can get a good handle on any calibration by comparing your time against any number of online power calibrations.

  107. Javier

    Hi DC – hope you´re doing well!
    Do you have info or comments about PowerCal Bluetooth Smart working connected to Wahoo Fitness App?

    • I haven’t tried it yet myself, but I’d be very surprised if it didn’t work.

    • Ryan

      The Wahoo Fitness App does not fully support PowerCal Bluetooth–the power data is not available. Here is a response from Wahoo customer support:

      “The Powercal is not a traditional Power meter. Currently, the app doesn’t support the power meter portion of the Powercal. We have this on our to-do list, but it is a low priority at this time. Please let me know if you have any other questions.”

    • Javier

      Hi Ryan and DC

      Thanks for your respectives comments. Here is the original question I raised to customer support pf Wahoo:

      “Since some weeks ago I have been looking for a Power Meter. As I do already
      have a Kickr trainer with Tickr HR and Blue SC sensors, don´t want to spend
      money in a GPS unit but centralize all data my iPhone 5s with Wahoo Fitness

      It has not been easy due to most of power meters in market works with ANT+
      such as Quarq and PowerTap. There are some others that works via Bluetooth
      such as Stages but its current model does not work for my SRAM Red22
      groupset. However I was noticed about PowerCal which is a HR strap sensor
      that has the ability to calculate power based on HR frequency.

      link to dcrainmaker.com

      Do you have info or comments about PowerCal Bluetooth Smart working
      connected to Wahoo Fitness App? If yes, is there a possibility to setup
      time or average of measurments?

      In other hand, do you at Wahoo recommend or suggest any other type of power
      meter that can be connected to Fitness App?”

      and here is the reply I received from Wahoo:

      “The Powercal should work with the Wahoo Fitness app, but we have heard reports from other customers that it is inconsistent. I am not sure if it is only with the Wahoo Fitness app or if the same happens in other apps”.

      So basically I can understand that it is not an adequate or suggested device to be used with Wahoo Fitness App. I wonder to know which power meter can be pared to Wahoo Fitness app.

      Best Regards!

    • Most other ANT+ power meters work just fine (I haven’t tried Bluetooth ones aside from Stags), so I’d probably go back to CycleOps/PowerTap and ask them if they can clarify their support policy there.

  108. jose

    Hello DC
    Do you know any android app that can work with this heart power meter? I’m interested in giving a try but I don’t want to spend money in any computer. I use my galaxy S5 for other ant+ sensor but any of those app say nothing about power meter.

  109. Stephen

    Different application than most – I coach flat water sprint and marathon kayak racing and use the Garmin 310XT and 910XT to capture HR/Speed/Time data. Power or Watt output would be a very useful parameter for on the water and erg training. An existing power measuring device for paddlesports is expensive and requires modification/calibration of the paddle shaft. Does anyone have experience with using the Powercal for paddlesports?

  110. Robert

    Hi Ray, first time I write, but I have been an avid reader for many years. Thanks for all the great reviews and advice!

    I just got a BTLE PowerCal and I’m looking for an iPhone app (other than PowerTap) supporting both HRM and Power signals correctly. So far, I’ve struck out, however, the folks at iSmoothRun seem to be at the forefront of BTLE sensors support with this comment on their Website: “All BT smart sensors are supported (HRMs, footpods, speed/cadence, power.)”. However, it is not possible to contact iSmoothRun from their Website, it can only be done from within the app, which cost $5.99. I will gladly spend these few bucks for full PowerCal support, but I am against the principle of throwing 6 dollars out the window to find out it doesn’t :-)

    Thanks in advance!

    • I’d go with the Wahoo Fitness app – it supports both…and is free, and uploads to virtually every 3rd party site out there. It’s what I use. :)

    • Robert

      Thanks for the quick reply Ray!

      I must be doing something wrong when setting up the Wahoo Fitness app. It detects my sensor as a Powercal and gives me HR reading, that’s it. No power reading is available. It shows instead of power:

      Any idea what the issue is?


    • Steve S

      My understanding and experience is that the only app to provide both HR and power metrics at the same time is the powercal app itself. Most apps will get HR via BT, but since the power data is proprietary coming out of the strap (and I think part of the HR data stream, according to Ray’s description) the only app to pick up both is the powercal app. Hope I’m wrong; the powercal app is clunky and recent update made it even clunkier.

    • Robert

      Thanks Steve for the comment!

      In my previous reply, something got dropped from my last sentence. It should have been: It shows “n/a” instead of power:

      I have the same complaints about the PowerCal app. It is very basic and has some potential, but needs more work.

      I really wish the Wahoo Fitness app would support both signals at the same time, I really like this app.

      I was able to find a Twitter exchange that seems to indicate that indeed, the Wahoo Fitness app should support both Powercal signals. Maybe I understand this wrong: link to twitter.com


    • Steve S

      I think that twitter exchange means that it should pick up power data from a separate power device, not the power cal strap.

      My biggest complaint about the latest power cal app update is that now each time I start a recording I have to tell it to pick up the power signal from the strap. 1st version of app let you set and the setting stuck. Now you set and it forgets – it actually forgets the power setting – the primary reason we have this particular strap in the first place. Ugh.

    • DFX

      Yep I have the same issue. I have contacted wahoo support, and initially they said it should be working, but once I showed the screenshot with power “N/A” it has been moved to development for investigation.
      Have you used the wahoo app with the powercal and obtained both HR and POWER data?

    • DFX

      Yeah Steve,
      I didn’t notice this ‘new’ feature until I had two rides done, and no power, only to find that the setting was somehow turned off, but never by me!
      It’s a pity the PowerTap app is so limited versus say Endomondo or Wahoo. At the moment, I run one of the above in parallel with PowerTap on any of my rides, which cant be good for iphone battery life.

    • Robert

      Steve S and DFX, I too am quite frustrated with the Powertap app limitations and “forgetfulness”.

      My hopes ar with the Wahoo Fitness app advertised ability to capture both signals from the PowerCal unit. However, my contact with the Wahoo support team has resulted in a similar response as the one Steve S got:

      Jonathan Vejjajiva (Wahoo Fitness Support)

      Aug 29 02:24 PM

      Hello Robert,

      I am sorry for our delay. We are currently doing some testing on this to see what the issue may be. I will let you know next week what we find out.

      Thank you,

      Next week is now, so I am crossing my fingers for a positive feedback from Wahoo Fitness in the coming days, but I won’t hold my breath… :-)

      In any event, I’ll post when I get more news.


    • Robert

      Sorry for double posting, I was trying to edit my first sentence to correct an error.

    • DFX

      Steve / Robert / Ray,
      I got some positive feedback from WAHOO support on this:

      Our developers have gotten to the bottom of the issue relating to the PowerCal. We will be releasing an update shortly. I will keep you updated.

      So I’m hopeful in a week or so, we see an update made available and it addresses it. Not sure how often they release updates, but I think it has been a while since I got one, I’m sure they bundle several fixes in an update – let’s make a note of the next update and see if this feature is working after it.

    • Robert

      I tried the new app version today and the guys at Wahoo Fitness got it to work right with PowerCal. It now records HR and Power at the same time.

      Wahoo Fitness is now one of the best apps, hopefully it will continue to improve!

    • Steve S

      Hallelujah. I’m so glad Wahoo figured this out. Being restricted to the clumsy nature of the Powertap App was a big bummer. I just tested Wahoo and found what Robert found – both the HR and Power data come through. @Robert – I have successfully enabled syncing to Strava and MMF -but is it true that with the Wahoo app you have to manually push/share the individual workouts to those other services and that it’s not automatic? Maybe I’m missing a setting for the automatic push to happen.

    • Steve S

      Hallelujah. I’m so glad Wahoo figured this out. Being restricted to the clumsy nature of the Powertap App was a big bummer. I just tested Wahoo and found what Robert found – both the HR and Power data come through. Robert – I have successfully enabled syncing to Strava and MMF -but is it true that with the Wahoo app you have to manually push/share the individual workouts to those other services and that it’s not automatic? Maybe I’m missing a setting for the automatic push to happen.

    • Robert

      Hi Steve,

      As far as I can tell, uploads from the Wahoo Fitness app are semi-automatic. The upload apps are easy to configure and must be triggered manually, which is fine with me. I prefer to control when the uploads happen in case there was a problem with the GPS tracking or data recording while riding. I always have 2 apps recording at the same time and upload with the backup app in case of issue with Wahoo Fitness. My backup app is PowerTap and I deactivated the automatic uploads for the reasons above. Before WF fixed the power data issue, my main and backup apps were the same in reversed order.


    • DFX

      Yep, got out for a ride today, and happy with the results from Wahoo… I can now park the powertap app in the background. Sometimes I need it to activate the connection to the powercal for both endomondo and wahoo, not sure why, but I can live with using it for that.

  111. Laurent Etur

    Hi Ray,
    Thanks for another great review!

    I just got a PowerCal and did my first calibration ride on the trainer. Everything works well as per your instructions above, but my Ant+ USB Stick won’t find the PowerCal HR strap…therefore I’m not able to pass the calibration info to the device. The Powercal HR strap seems to work fine as it does send both HR and Power signals to my Garmin 310XT…but I hope to complete the calibration as the power numbers currently displayed are way off the mark.

    Any ideas what could be happening?
    I’ve tried to contact support but so far they haven’t been able to help.


    • Since you have the FR310XT, double check that neither the ANT Agent software nor Garmin Express are running (either in the background or open), they’ll block the connection on the USB stick.

    • Laurent Etur

      Hi Ray,

      Thanks for the tip, this did the trick. It’s not very intuitive that you have to stop Ant Agent, and I had been trying various things for the last 24h without success. Now I can try it out on the next rides!
      I really enjoy your blog, thanks for the great contents.

      BTW, might see you around one of these days as I live in Paris (15th).


    • Awesome! And don’t be a stranger!

  112. Oisin


    Does anyone know of some software which does approximately what this device does, but by adding power data to a TCX (or similar) file after thw workout?
    I do not need to know my power values during my ride, but I’d like to be able to create the data after the ride.
    I would use this for times when I need to ride a bike without a PM.



    • Mr Nofish

      Oisin, I’m not aware of anything ready-made, but there’s a tcx_power python script out there that doesn’t really work too well IMO, but is well-written enough that you could probably hack it to do what you want (I did something like that but estimating speed instead of heart rate, but that’s simpler because it doesn’t require calculating any derivative)

      At least one blogger has suggested a formula that might produce similar results. Of course you could test it beforehand in a spreadsheet to see how well it works and what tuning might be necessary.

    • jose

      Hello oisin
      There is an app for android that calculate power in the phone and create and .tcx file as you which.the app name is bicycle power meter.I used it and like it.

    • David George

      You can import TCX, Fit and GPX files into Wattzap and it will calculate the “power” based on speed, road gradient and your weight. It is not going to be that accurate but maybe not too bad for climbs.

      link to wattzap.com

      I think Golden Cheetah might do the same.

    • Mr Nofish

      Golden Cheetah will only calculate power in train mode if using one of the supported trainers – for outdoor use, I’m importing the TCX files with estimated power produced from my modified tcx_vpower.py into GC.

      The inputs are: speed, total mass, slope, average temperature and pressure.

      From skimming the site Wattzap doesn’t look all that different from TrainerRoad.

  113. Mr Nofish

    “8. Without calibration (only entering rider’s weight and choosing bicycle type), average power for a given ride typically correlates to within 15% (with no drafting) of a conventional power meter.”

    I would argue a 15% error on the ride average is not something to boast about, the PowerCal is much closer than that, without calibration either.

    “2. How accurate is the power data? For a solo ride (no drafting), typical ride averages correlate to within 15% of expensive crank based power meters such as the Quarq CinQo which require periodic calibration. For group rides when drafting, the power will read higher than actual unless you are leading.”

    That last remark seem to suggest power is simply derived from the usual speed calculations, and HR is simply recorded to the TCX – however the PowerCal is not misled by drafting or going downhill.

    “Ride up to highest speed reasonably possible to maximize the aerodynamic drag (20mph) ”


  114. Mr Nofish

    Sorry for the confusion Ray, I was commenting on the app jose mentioned but for whatever reason the threading came out wrong.

  115. John Mo

    My experience with the PowerCal – positive!

    I picked up a PowerCal a couple weeks ago to supplement the PowerTap(s) ive used for years on my road an tri bikes. I’ve been doing more MTB riding lately and I’m not willing to spend ~$1k to document my dirty escapades. My experience has been almost identical to your write up, with believable average numbers, some strangeness on the downhill sections, and generally low numbers no sprints. (I use 10sec Avg on my display and I have never seen a number over 300W, even when I might hit 5-600W on the same hill on my road bike).
    I’m also riding CX as of this year (with a new axle standard so my existing PowerTap doesn’t fit), so this will provide some data on those rides / races as well.

    I’ve been quite happy with the overall data and performance – I didn’t expect it to perform as accurately as a direct-force meter, but for $100 it is a great way to fill in data on odd-bikes.

  116. Eli

    So if you want to save money on a power tap wheel set buy a powercal :link to powertap.com

  117. Shane

    Has anyone been able to find a way to get the bluetooth powercal’s power info on an android device? By powertap stating that the powercal would work with all BLE devices I was under the impression it would work with my phone (LG G3), but as it turns out (unless someone here can help) I have a $120 heartrate strap. The powertap mobile app is ios only and the android version of wahoo fitness does not support the powercal (or at least the power meter portion, heart rate works great).

    • Hmm, I can’t remember offhand, but have you checked ipBike? I think they might now support BLE power meters.

    • Shane

      Thanks Ray, I really appreciate the reply and all the reviews. I tried ipbike this morning after joining the ipsensor bluetooth beta, and I think ipbike is going to do the trick. There are a lot of options and customization options which I have not fully gone through and I don’t think I had it setup quite right this morning, but I do think it’s going to work. Thanks again, I was really disappointed with my purchase before you pointed this out.

  118. David George

    Looking at just the Heart Rate side of the Powercal I noticed that it is a lot more sensitive than a Decathlon HR strap I have. That is it reacts much quicker to changes in HR. I’ve had less spurious readings with it too.

    • DFX

      Hello Mr. George,
      I would agree with your first statement the the powercal is more sensitive, but because of that I’ve had a lot more ‘wildly high’ readings… than say my older polar HRM – but that could be to do with the strap rather than the unit, and those high readings are short lived generally, so don’t annoy me too much.

  119. Mr Nofish

    TBH I’m not sure one can even notice actual differences between different HR transmitters especially using Garmin units as they are not updating the screen more than just every now and then – in the power meter community keen eyes went as far as to call them laggy.

    Having compared my old Polar HRM to my Garmin (which means wearing both transmitters at the same time or the only meaningful way to compare them), it’s clear the Polar is updating the screen more often, but as far as actual values, I can’t say one is more reactive than the other.

    FTR the Decathlon/B’Twin ANT+ transmitter used to be exactly the same used by O-Synce, unless they’ve made changes.

  120. nate

    some advertising part of this website is making the actual text unreadable on mobile devices despite it loading as “mobile friendly”, please deactivate it.

  121. Frans

    The sampling rate of the Powertap Powercal is much higher than your average HR sensor.

    The formula I found on the interweb: A*HR – B + C*deltaHR/deltaTime.

    ‘A’ is the slope of the curve. So with every extra BPM you will push out A more watts (default value is 2.550) but you don’t generate 255.0 watts out with a heartrate of 100… this is corrected by factor B (-190); you could say B is the offset of the linear relation between HR and watts (which is true for steady state power vs heartrate). This is also why you need a real power measurement to calibrate; otherwise you will not know the difference between the calculated value and the real value. Leaves us with Factor C… this is called responsiveness by Powertab in PowerAgent. If your HR changes from the previous measurement the delta is multiplied by factor C and than divided by time that has passed since the change. This makes the Powercal drop to (almost) zero when over a hillclimb and shoot up when accelerating. The steady state power will almost be on the line defined by factor A & B.

    I dont know if this is really the formula Powertap uses, but it explains a lot the way it works and estimates power. You can still calibrate the Powercal with PowerAgent 7.7.5 and for the price it is still a bargain imho.

    BTW: awesome site DC Rainmaker, love the detailed reviews

    • brent

      Your formula seems okay and matches my experience with how it reacts. When I did the calibration I had to choose the C parameter as there was no recommendation. I chose 150 as the original default was 150. I only use it for an estimate of TSS. There are a couple of issues. Firstly my variability index with powercal comes out low which probably underestimates TSS. At low HR and fast increase results in a really large power and at high heart rates an interval does not shift your HR much therefore it does not reflect power well. But over a period of time can be good. I road up a 11 minute hill recently and the powercal averaged 360 watts. Online power calculator for the ride was 357 watts. If you get a good calibration I think you can expect within 5% mostly of reality over a period of time.

  122. qbroad

    Ray, love your reviews. A triathlete and data junkie makes for great reading. I was very interested in the powercal given I compete in ironman and figure that long sustained efforts are where this product should shine. I have a powertap on a training wheel (busted my race 404) and purchased the stages power for shimano Of course, I buy a new bike (P5) and I have two issues, new wheels aren’t mapped to a power tap, and the Rotor crank doesn’t have a stages option. Thinking I would deliver a cheap(er) alternative, I ordered a DuraAce crank for my bike, only to realize the stages crank won’t fit the P5! So now I will use the powercal and my powertap training wheel during on-course training and then map them together to determine the appropriate power level for race day.
    As others have suggested, your work is outstanding and is the first point of reference prior to buying new triathlon toys. I have used Clever Training for the purchase.

    • DFX

      Could you do a lot of us powercal only people a favour, and also use the powercal on your bikes with other powermeters… just to give us an idea on their accuracy in general?
      For me I will use my powercal with an assumption of inaccuracy, but at least consistency, so if I look at my data in isolation it will still work for me and give me an indication of progress and what I could / should race at (both power and heart) for a given duration/race. But I would like to have some long-term data. A friend has a powertap, and just on the short tests I did with his there were inaccuracies, but the longest I tested was 20 mins on his bike (which is not a great fit for me).

    • Thanks for the support qbroad, I appreciate it!

    • qbroad

      DFX, i will use the powercal indoors during training, where I currently work out at a computrainer studio (wattsup cycling). I will have that to compare with my powertap (using a garmin 500) and the powercal, using the Garmin 910xt. I have a 12 hour cycling race in February where I will compare the stagespower with the powercal. The key is just determining what my corresponding z1-z5 power levels are with the powercal, clearly it only matters that the power readings are consistent for me (whether it is 100W, 200W or 300W only matters for bragging rights), but I will provide some benchmarking for the variance to the different measurement tools.

    • quentin broad

      I have done my comparisons of the powercal (PC) to my powertap (PT) and stages using a computrainer as the base power level. I am not sure if I can upload an excel file, but the results suggest the following: after warming up for 30 minutes and recalibrating the computrainer I completed 3 x10minutes at power readings of 190W, 210W and 230W. I calibrated my PT but the PC is out of the box. I captured the readings from my PT on a garmin 910xt and the PC was loaded up to a garmin 500. The NP for the whole session was 204W for PT & 203W for PC. AT 190W the PT showed avg power of 205W and the PC was 205. At 210W, the PT was 222 avg power and 236 for PC and finally at 230W the PT was 240 and the PC was 237. The PT deviated btwn 4.3% to 7.9% for the three 10 min measuring periods, whereas the PC was 3% to 12.4% of deviation. The deviation btwn the PT and the PC was minimal on either end but 6.3% at 210 watts. The variability of the PC was significant with max power readings 2-3x the max power of the PT. This doesn’t represent the same level of analysis that Ray puts into his reviews but hopefully it gives you some sense that powercal does a reasonable job over a significant interval.

  123. Raphael

    Hi Ray,

    Thanks for your awesome site and the effort you are doing. I read it for a a few years now and you have been a great source for product review and knowledge.

    I wanted to dive into the powermeter market and was wondering about the powercal. I think it would fit perfect for me, a biker for just love numbers and datas.

    I found the product on these two website:
    link to cycleops.com
    link to powertap.com

    What is the exact difference of those 2 products aside of the price? Is one (aka the more expensive) a newer version? Is one better used for cycling?

    Thanks in advance for your help.

  124. Doug

    First, thanks for the review of all of the products on your website. I bought a powercal last year, after reading your review. I wanted to share my own experience, in case others like me come to your site.
    First, I am not in the best shape. I guess I would describe myself as a fairly avid rider who spends too much time on the couch. I was 53 last year, rode about 2200 miles, and am probably 40 pounds out of good shape, and probably 60 pounds over what a decent professional would weigh for my size. I also ride in Texas, during the summer, in a lot of heat.

    All of the above leads to a lot of cardiac drift. After about 60 minutes on the bike, the PowerCal is essentially useless for me. It will say I’m putting out 220 watts while tooling along a flat at 14 miles an hour. I don’t have access to a “real” power meter, but Strava estimates ~105 watts for me for that output, which compares closely to any online calculator.

    Another thing that irritated me is that it doesn’t use any other data from the Garmin unit it is paired with to make it’s wattage calculation. I don’t know anything about ANT+, so perhaps the strap has no access to the Garmin data, but it seems to me a product like this would be a lot more useful if it could look at cadence and change in altitude and have some algorithm based on that. I stopped using it after numerous times of watching it indicate 200 watts on a downhill when I’m not peddling at all.

    As other have pointed out, if we assume a season where we begin out of shape, and get in better shape as it goes on, our heart rate should show fewer BPM for a given output. The powercal will show you to be working harder for that output in the early season than it does later. That alone should be enough to keep anyone from buying the product.

  125. Mr Nofish

    Doug have you talked to a doctor? Given how the Powercal is supposed to work, your findings sound exceedingly strange to me. Also, watch your hydration: in hot humid weather I usually drink plenty before going out and if possible get more water along the way, as 2 bottles would last maybe 2 hours.

    Strava and most other online calculators don’t keep track of things like wind and drafting which is why a PowerCal is a more useful tool than any of them. The only way to get figures in the ballpark from those sources is steep climbs. To just to give you a couple of examples.

    I have ridden threshold in strong wind at 21-25 kph whereas my speed in average conditions (i.e. not still air) for that level of effort is 36-38 kph – Strava and the online calcs would claim I was slacking regardless of my heart rate or PE.

    OTOH I’ve ridden groups at 42-44 kph at low tempo effort, and Strava would just overstate my power output massively.

    Don’t even look at pros, for all intents and purposes you can think of them as aliens. Just focus on your progress and losing excess fat. Good luck!

  126. Hi Ray,

    I realize this is an old review and hope it isn’t off your radar. There was 1 question about a comparison to Strava power calculations which you had not done. I’ve searched DCRainmaker and can’t find a followup.

    I’m solidly in “your Dad’s” group and try to get in 50 to 75 miles/week with a Garmin 500. I upload to RWGPS which has a power calculation and wonder if there is much point in switching from the Garmin strap to the PowerCal?

    I would not imagine you have any access to the algorithms used so if there hasn’t been a direct comparison an answer would be your opinion but I’ve followed you for a while and I’m certain your opinion will be much better and more useful than most.

    Thanks for all the great reviews, comparisons and analysis.

    Mike Hare

    • Mr Nofish

      Mike, it’s better than calculators because it accounts for things like wind and drafting that calculators have no clue about.

      OTOH unless those miles are constant climbing, you probably don’t need anything more sophisticated than a HR monitor. You can still use techniques inspired by power based training with only a HRM, check out Carmichael’s Time Crunched Cyclist book.

      That said, the PowerCal is still a lot cheaper than any power meter, so if you’d like to have the extra metrics without having to do any extra work yourself, and you don’t mind the price tag, go ahead.

      IMO it’s been on the market for some time and power meters are dropping, so a price cut would make it that much more appealing.

  127. Brian C

    Okay thanks as always Ray for your reviews!

    I was convinced by some of the recent comments regarding wahoo app reading the Powercal that I decided to give it a try. However upon receiving and connecting to my wahoo as both HRM and power device, the app flat refuses to see the Powercal as an HRM when entered into a workout. At least it sees it as Power and I can wear a second HRM to capture that but isn’t it supposed to read it as both?

  128. Brian C

    To add further detail to the above, my Wahoo app will recognize BOTH HR and power under “saved sensors” but then when I attempt to start an activity/workout it only sees the one device as power and endlessly cycles/circles/looks for that same HRM that it just saw under “saved sensors.”

    This is downright maddening.

  129. dfx

    Brian C,
    Is your powercal Bluetooth or ant ?
    Do you have the powercal app installed on your phone?
    I never use the app unless I have a problem connecting. Then if I use the powercal app it will find the device and wake it up, where wahoo wont. The only other thing in the app is the setting for “Power[W]” within the HR Sensor, which must be on, for both HR and POWR to be seen by wahoo.

    • I double-checked with the Wahoo folks as well. They’ve got a bunch of other folks on the PowerCal and haven’t heard of any issues. But they’re going to double-check that nothing was broken accidentally in a recent build.

  130. Brian

    Thanks for the replies guys.

    With alot of fiddling around, I managed to get it to work. Here’s what fixed it:

    Originally I had all my workout profiles set up in Wahoo (cycling, indoor cycling, mtn biking, etc). So when I added the PowerCal to “saved sensors” I simply checked all those profiles for the new unit.

    Yet when I went into the “cycling” profile, or the “mtn biking” profile etc, the scenario I described above would manifest (i.e. wahoo would see the powercal in saved sensors, but then refuse to see it as an HRM in an actual activity).

    So what I did next was create a brand new workout profile (which I called “CyclingPowerCal”) and saved the Powercal to that profile (along with my speed/cadence sensor), but no other sensors.

    That worked, and I was able to do a ride yesterday capturing both HR and Power metrics.

  131. Brian

    Does anybody know how to configure Wahoo to show Power metrics beyond instantaneous? I was hoping I could configure a data page, but there are only a few from which to choose from what I can tell.

    I would prefer to see something smoothed out by 10sec at least.

  132. Brian

    Hey Ray – Apologies for posting this here, it was the most suitable place I could find for this question.

    What is the most cost effective method you can suggest for a device display to show 30sec/60sec/5min/etc power averages out of this Powercal device? Wahoo’s app doesn’t do anything but instantaneous.

    It could be an (iOS) app, some watch, or a bike-specific handlebar computer.

    I see the 310xt could be had for about $140 right now on Amazon. I know that’s an option, and I could leverage that $$ towards my running too…but I really think there has got to be something else that would do this cheaper.

    Appreciate any advice in advance.

  133. Paul Impellezzeri

    Has anyone tried the bluetooth PowerCal with a Polar V800? I know the V800 doesn’t work with some bluetooth powermeters. I have a Powertap for my bike, but would love to have something I can use for spin class.

  134. Steve S

    Small update from discussions months ago about apps that can show both HR and power from the PowerCal strap-

    This may have been working like this for a while, but the Strava iOS app now picks up both the HR and power data streams from my bluetooth version of the PowerCal strap. This means that now 3 apps can pick up the power data and HR data simultaneously I think: the PowerCal app of course, Wahoo Fitness, and now Strava. Strava’s Stats screen does not show the power reading metrics unless you tap the power/hr icon at the top and then it gives you a hint at what it is at that point. I’m not sure if Strava’s “Stats” screen is customizable – it looks pretty limited with what it can show – not nearly like the Stats that Wahoo’s app provides.

  135. Brian

    Thanks for the update Steve. I think right now Wahoo is the best one going. You can view Power in its own data screen, or in the Biking screen that allows you to tap the screen to change from Current/Average/LapAverage/PrevLapAverage. Pretty cool.

    FWIW – There appears to be a bug in Wahoo though in the Lap Average screen as it is clearly NOT lap average for at least HR/Speed/Power. It seems to be something more like 10sec avg instead.

    Also, another bug in Wahoo’s app is that for the Power datascreen, there is a subsection that is supposed to show 10sec/60sec/5min/20min/60min averages for Power. However, these fields instead show MAX for those increments instead. A Wahoo rep told me they were supposed to be averages, though there is no indicator on the screen either way.

    Can anyone that is using the Wahoo/PowerCal combination confirm on your devices what I wrote above? I am wondering if it’s just my device/app.

  136. Joe

    Thanks, based on a brief mention in one of your podcasts that intrigued me, and following up with this review, I bought it through your CleverTraining link, so thanks for that. I figured it would be a good intro device into power meters

    I realize this is an old review but I was wondering if you’ve paired this with a FR920xt yet? I had no problem with the initial pairing of both the power and HR, but then both the power & HR drop out and re-pair at apparently random intervals, where it will not be connected for 10s to a minute, and then stay connected for 30s to a couple minutes. First this happened at a spin class, so I thought maybe there could be interference with any of the 20+ other people there, and then I put on my Garmin HRM, while keeping the PowerCal on for power only, so both were sending. I got a solid HR signal from the Garmin, as usual, with spotty Power readings from the PowerCal.

    When I got home, I tried again, this time w/o any other people or devices nearby, but ended up with the same spotty connection problem. I haven’t connected PowerTap’s customer service yet (it’s the weekend), so I was just wondering if you’ve seen or heard of anything like this yet. I didn’t see anything when I Googled for a problem like this. I ended up buying two different PowerCal units, one branded as CycleOps (through Amazon) and the other as PowerTap (CleverTraining), and both acted exactly the same way. I’ve since returned the CycleOps unit, but I’m holding on the the PowerTap for the time being, hoping that this can somehow be resolved.

    Thus far, my FR920xt has not had any issues with the HRM, cadence, and speed sensors (all Garmin) that I use.

    • Hmm, odd. I haven’t tried that pairing yet. That said, what you’re noting sounds very much like a CR2032 battery starting to die. Have you swapped it recently?

      Failing that – I’d drop a comment on the FR920XT in-depth review, as you might get a more targeted response there (since a gazillion more people subscribe to that posts comments)

    • Joe

      Thanks! I forgot to mention that I did replace the battery in both, and got the spotty results. I’ll post something similar in the FR920xt review, and I submitted a form to PowerTap

    • brent

      It also sounds a bit like the old hrm low contact issues. The powercals (and I have one) like most hrm have an issue with not working without a good electrical connection.. Its most evident at the start. If I wet the electrical pads (the olde spit wetting tecniqque) it may work for a couple of minutes then it stops. There may be a period of no signal interspaced with really high hr and power numbers. After a while when I get a good sweat up it will give consistent numbers, it can take 10 minutes on a cold dry weather period. Powercals and old hrm can really suffer from it. But for me some older hrm are better and newer ones can be worse.

    • Joe

      Interesting. Thanks for the info. I am ordering some electrode jelly to get a better connection, so we’ll see if that works. However, the first time I had the problem, I wore it for 45 minutes and definitely worked up a sweat, with no apparent improvement. Maybe it will work better when I put the electrode gel on from the beginning.

    • Brian

      Joe – When you say “spotty” do you mean that your 920 is not showing readings at that time? When you check the file later in Garmin Connect, are those time periods shown as drop outs or spikes?

      The reason I ask is that I use the Wahoo app for my powercal connection, and when mine goes all wonky with the spikes, the Wahoo app shows them on the device as dropouts, not spikes.

    • Joe

      Brian, they’re just dropouts. On the graph on Garmin Connect, it just comes across as zero watts for those periods. My issue wasn’t with spikes, but with the PowerCal repeatedly disconnecting from my 920xt, and then automatically reconnecting. So I was just getting no readings for the disconnected time.

  137. Brian

    I have become increasingly frustrated with this device and the “spikes.” I’m old hat at chest strap HRMs, so I know all the tricks to employ, but this device seems to be worse than others. And strangely, lately I’ve been getting the crazy spikes late in my rides, when I’ve worked up almost *too* much sweat. (all of this is happening in summer here in Southeast US, when I typically don’t have issues with other chest HRMs)

    It makes the HR and Power averages overall just completely useless.

    • brent

      I’ve had mine for some time and used it extensively. Eventually it has developed a problem which I think is waterproofing failure. After drying out it would last for about 90 minutes and then stop working. I have silicone on the battery cover and sticky taped the entire module and it actually has fixed the issue. Mine has probably done > 20000 km though in some very hot conditions.

    • Brian

      Thanks, Brent. Also I appreciate all the advice you’ve given in this comments stream.

      FYI – In case you want to replace your waterproofed version, the PowerCals have really dropped in price recently, I got mine on amazon for around $50.

  138. Anthony

    I have exactly the same problem as Brian, lots of spikes and mainly late in my rides. It seems to be worse when it is windy (which is always here) and when I have a thicker jersey on and not so bad with a thin summer jersey and good weather. When it is raining and windy, though, the powercal becomes useless. Thankfully I have no need for it now that I have a Stages powermeter and my old Garmin HRM never spikes at all. Apart from the spikes I have to say the powercal was pretty good.

  139. Brian

    Thanks, Anthony. Mine is pretty consistant with getting the spikes late into rides. Not sure if it’s Brent’s waterproofing issue or not, I guess I will see once the weather cools off and I’m not completely soaked as a result in these long rides.

    So far the PowerCal #s have been “interesting” but I haven’t really found a way to implement the #’s in training yet. I think this is mostly because I don’t have a head-unit that will display the appropriately smoothed numbers. The Wahoo Fitness App I use does not show 10/30/60 sec averages, even though there are specific fields just for those metrics. Instead, the app shows the Max for those ranges instead. Seems to be a bug with the app but Wahoo reps say it’s not and that the PowerCal is to blame. Oh well.

  140. Eric Woods

    Has anyone tried to swim with the Powercal. Just wanted to see if I could do a triathlon in it. Thank for all of your great equipment reviews.

  141. Gabrie

    Does anyone know if a PT SL 2.4 hub would calibrate at the same values on a Garmin 510 or 920 than on a Joule, because I have two friends which their PT calibrates around – 12000/-15000 but their power output seems to be around right!

  142. Jim in Colorado

    I purchased a PowerCal based on Ray’s review. Initially, it was close to worthless. I have direct-force power meters on my other bikes, have been riding, training, and racing with power meters for about 8 years, and have a pretty good sense of how much power I’m putting out. I bought a fat bike to ride in the snow/ice in the winter and wanted power files in order to be able to track my ATL and CTL. This was definitely a “close is good enough” use case.

    But the PowerCal numbers felt 20-30% low much of the time, did not respond to short hard efforts at all, and the TSS generated from the ride felt like half of what I expected. I used the PowerCal with a bike with an SRM and it confirmed my experience.

    I followed the configuration protocol, used the PowerTap appication, got the power curves to just about match, and hit the trail with high expectations. While there was some improvement, it was still unacceptable. But I used that ride to tune it again, got it closer, did another protocol-based ride on a trainer, tuned it some more, and it is now quite close most of the time. Still slow to respond to increased efforts, but that seems to be offset (from a TSS perspective) by being a little slow to respond to decreased efforts and to coasting.

    Some factors that may influence my experience: I’ve been training and racing for years and the PowerCal is likely calibrated for people who have not been training as long/much, I am strictly a cyclist (very little running and no swimming) so perhaps am more efficient, and am probably a few years older than their target market so my HR range is more compressed.

    I don’t recall what values I ended up with, but a PT rep told me via PowerChat on the web site to not change the “Responsiveness” value, so I didn’t change that at first. But that was actually key to getting reasonable results -increasing it to 160 or 180 or something like was critical to getting the calibration close enough.

    Somewhere in these comments, Frans described the 3 variables that PowerTap lets you adjust in the configuration tool. The variables are not described anywhere in the tool, so I was just tweaking without real understanding of what the variables meant. Now that I have that info, I may try it again just to see if I can get it even closer.

    Ray reported that PowerTap had a study done that showed calibrating did not have a positive impact for most people. That was MOST DEFINITELY NOT my experience. it was worthless before calibrating and is now close enough that I find it useful during the ride and rely on it for TSS. I’m not using it for serious training intervals, just for “fun” rides, but I need the TSS for tracking my training.

    I almost sent it back, but after 3 or 4 calibration adjustments, it’s working for my purposes now.

    • Jim in Colorado

      Wow, that ended up being longer than expected, but I can’t seem to edit it to shorten it or correct typos. Oh well, hope that helps!

    • DFX

      Hi Jim,
      Can you share the calibration / configuration changes you have made? I only have a powercal, but friends have PowerTap’s on their bikes. I get to compare the powercal to the powertap from time to time when I do an indoor session and they lend me their bike(s). the Powercal would always deviate, and I can accept that for short activites it will be inaccurate. But I have never tweaked it, as I honeslty didn’t think I could. My philosophy has been if I only train with powercal and take it as the ‘truth’, if I always compare and my numbers are going int he right direction, then I am getting better. But it would be nice it my numbers really were ‘close to the truth’.

    • Jim in Colorado

      As Brent experienced, the only info I could find was in Ray’s review. When I calibrated, there was no info on what the 3 variables represented, so I made changes and tried to figure out what was different on the chart. That made calibrating very challenging. PowerTap really ought to post and explanation of the 3 variables and guidelines for calibrating. There is no disadvantage for them, especially if they include a “Return to original settings” button.

      I ended up with A: 3.1, B: -200, and C: 180. Based on Frans’ post, that appears to mean 3w / bpm and higher responsiveness. Perhaps the “-200” means that every bpm change counts whereas with the original numbers it had a “floor” where changes below a certain bpm level did not affect the power reading.

      It seems clear that the calibration values are affected by fitness because it affects watts per heartbeat increase. I’m a Cat 4 road / Cat 3 CX / Cat 2 mountain bike racer, so my fitness is likely higher than the average non-racer and lower than the really fast guys. The calibration is also affected by age because the heart beat range compresses as you get older. I’m over 50. My max HR was 184 when I first started training with an HR monitor at age 46. My max observed HR in the last 12 months is 178. Thus, a 1 bpm increase for me might indicate 3w increase in power whereas the same 1bpm increase for a 20-something might indicate a 2w increase in power. Those are just made-up-on-the-fly example numbers, not scientific in any way.

      Curiously, my low-end HR zones have stayed the same with 148bpm being the onset of training effect and a aerobic threshold of 167-168bpm. So my range of normal cycling remains about 20bpm, but Zone 4 and Zone 5 have compressed. Which likely also means that the rate of change has compressed and that is why the “Responsiveness” value needed to be higher for me.

      My point is that the values that improved the accuracy of my PowerCal may not work for others unless you’re about the same fitness and have the same HR range. But I hope my experience helps others.

      I may try another calibration now that I have an understanding of the 3 variables and see if I can improve further on the accuracy of the PowerCal. Though I’m pretty confident it is meeting my use case of tracking TSS on moderate-intensity fat bike rides in the snow and ice of Colorado.

    • Good stuff.

      I’ve actually started using the PowerCal again (mostly because I want to use it to demonstrate something totally unrelated), so this is interesting to try and give it another whirl since it’s been a few years, in terms of calibration.

    • Mr Nofish

      Does the program let the user change the various numeric parameters manually or is it mandatory to have a power file provided?

      In the latter case, does it support importing a TCX file with Virtual Power data?

  143. Kevin K

    Can I confirm something in your description of the calibration process.
    Below you note 6 stages in the calibration protocol from ‘warm up’ to ‘very hard’.

    Calibration Test Protocol
    5 min warm up
    3 min Very Easy
    3 min Easy
    3 min Moderate
    3 min Moderately Hard
    3 min Very Hard

    But when the test is complete and imported into the PowerAgent I only need hightlight from ‘warmup’ to ‘stage 5’ Moderately Hard?

    Is that correct not to include the ‘Very Hard’ part and if so why?

  144. dazza vazza

    Hi DC Rainmaker, I purchased a powerops trainer with the powercal. i enjoy the use of the indoor power trainer with the Joule GPS device. I travel for work, is it possible to pair the powercal with a phone and a app for heart rate training? i tried to pair it with my iPhone and Nokia windows phone and it cannot be found. is this a possible solution for remote/travel training so i don’t need to take my Joule headunit? (similar to how a Polar H7 pairs to a phone for use with fitness apps)
    thanks in advance Darian

  145. Kevin K

    I tried the calibration method in DCs post and if I used the whole file my numbers came out as
    a. 2.513
    b, -145.9
    c. left as standard 150

    This gave me a result over a 1:20hr ride about 60watts too high.

    Tried highlighting just to the end of the 5th interval and the numbers are

    a. 2.400
    b. -132.1
    c. standard 150

    Again over 1:20 hr ride 50 watts too high?

    I am 45 with a max HR of 184 and an FTP of 255.

    Cant get this anywhere near me!!!

    • brent

      Using a trainer is is possible but very very hard to get a good calibration.
      You have to be very discipined and SMOOTH and it took me several goes. My FTP is about 350 to 355 so i started at 200 and stepped up in 50’s until i got to 400.

    • Kevin K

      Thanks Brent,
      was it B. or C. that you started at 200?

      Would you mind posting your numbers just for reference.

    • Kevin K

      Used ERG mode on a KICKR and dont think I could have done any better.
      Just about Maxed my heart and nearly didnt have enough to finish

    • brent

      when I did mine I only had the 5 3 minute tests in my file. I did not include the warm u

    • Timothy Allen Compton

      You can edit the parameters manually in PowerAgent, from any calibration run, to adjust readings to match what you are producing. Read previous posts which describe what a b c mean.

      I used Excel to graph both what the calibration should give me and what I would like to see. If you’re not comfortable with Excel graphs (or other graphing program) adjust the parameters (possibly take your b and subtract 50, i.e.: if -200 change to -250) and see what happens. I have not done this for awhile so can’t give good directions but I was way off after calibration and get good results after I changed parameters over a year ago.

      I find it easier to play with the parameters than to try to re-run the calibration.

  146. Mark Duncombe

    A cunning plan…

    So I use a Kickr with Zwift and it has changed the way I train and exercise. Zwift is just taking the transmitted power value from any device that produces it. So there is no reason why Powercal wouldn’t work with Zwift, indeed some research shows that people do use them together.

    Here is the crafty bit. I also have an old Waterower that has no console and therefore no built in way to monitor or log a workout. OK, I could work to heart rate old school style but why not use a Powercal and row my way round Watopia! Zwift would help give the workout structure and make it fun.

    I could also use the Powercal out on my road bike, on my mountain bike and when I hire a bike in Mallorca. I am not superfussed about accurate power, I just want to give my workings some meaning.

    A Powercal is starting to have some appeal.

  147. Mathew

    Hey, I was wondering if you know if the new bluetooth will be compatible with the tomtom multisport watch? I know that it may not display the power on the watch but once the data is uploaded will it show the information on strava?


  148. Derek

    Does anyone use the PowerCal with a Cateye Stealth 50 head unit? If so, does it allow you display Average Power? Or will it only show the current Power reading which I understand can fluctuate quite dramatically.

    Also, after uploading the ride file, does it show the sampled power measurements every 1, 2 or 5 seconds over the entire ride?

  149. Glen

    Good review and in so many ways correct. If you’re a weekend warrior and regular commuter, yes, this will be a great tool to use, as long as you only use it to monitor your own performance rather than compare yours to others.
    In saying this, and on another note, should serious training require the purchase of a power meter that measures at the crank, or rather, at the rear wheel (Hub type)?
    You never see stats of motor cars or power boats measuring from their crankshaft, only from their rear wheels/prop?
    This thought has always been the point that has stopped me purchasing an expensive power meter attached to the crank, as you are not really measuring what actually gets to the rear wheel, what are your thoughts on this?

  150. Tom

    Hi Ray!

    Love your work here, you’re the first place I goto before buying anything!

    I have a questions on the powercal, I’ve been looking at the bluetooth version and I know this is an older review. Have you tested the newer version? I’ve been reading a lot of medocure to poor reviews especially with the HR portion dropping out and screwing up the power calculations.

    I also use the M400 and M450 for my cycling computers… are you aware of any comparability issues?

  151. william vermeulen

    When I’m training in Zone 2 for a 3 hour ride my heart rate average seems to rise as time and temperatures rise even though I feel like I’m putting out the same power. Do these power readings go up with cardiac drift or is it more accurate like a power meter?

  152. David

    Ray, one question do you have the opportunity to test the new PowerTap PowerCal (dual or BLE) in order to know if it is compatible with Polar devices such V650, m460, m450 or V800. If you tested could you let me know if you can red ppm as well as watts in the device or you can only read one signal. Best!!

    • Peter Nichols

      Hi, I have the dual band PowerCal working correctly with the Polar M460 (both HR and Power) I also have a V650 and that only appears to pick up the Heart Rate not the the power meter stream. Hope that helps

  153. IvanDobski

    After playing around with Powerpods for a couple of years I’m quite taken with the idea of none dfpms, I’m getting a pedal based system for my road bike but have just bought one of these for the gravel/mtb bikes.

    Presumably (and that’s probably my first mistake) I could do the calibration ride on a smart trainer – essentially design a workout around Watopia and off I go?

  154. Student Of Life

    Hey Ray (and other DC Rainmaker users)!

    Being I don’t currently have access to a trainer but I do have a gym membership that has spin and gym bikes – would using this plus something like Zwift on my Ipad be a viable option for at least meaningful training ?

  155. Aydin

    Reading your last response from August do you confirm this is still the only option to continue training on Zwift with power history when Hotel/Gym does not allow a frequent traveler like me to swap pedals?

  156. manuel

    i bought a powercal band and it doesnt work with 3 garmin models (920/735/fenix 3 )
    is there any tip to pair the band with garmin watches ?

    thanks .

    • brent sword

      I never had trouble pairing it with any garmin on ant+. If you have the Bluetooth model it will not pair on any garmin that does not do Bluetooth pairing. Which is most except the very recent ones I think.

  157. mathieu valotaire

    I just purchased this at a bargain price.

    Your review help me a lot and this will be a very nice hotel zwift-rouvy-alleviate-the-boredom tool!

  158. Garmin 1030

    The Powercalls will work with Garmin 1030.
    Thank you

    • Yes, it’s compatible with the Edge 1030.

    • okrunner

      I have a bluetooth Powercal and recently it is no longer pairing as a power meter with the Edge 1030. Wondering if this is an issue with a recent Garmin update (13.75) or something with the Powercal. The Powercal seems to pair with other devices but I haven’t tried it on a ride. I’m having other pairing issues since the new update with my radar but at least it’s mostly working. Any thoughts?

  159. Jeremiah

    I’m looking to get one of these but they’re discontinued and I can’t find any on ebay. Would you be interested in selling yours?