Kickr v5 vs Favero Assioma Power Accuracy

I recently got a Wahoo kickr v5 smart trainer and it does not require any spin-down calibration according to wahoo. I also have a Favero assioma single sided pedal powermeter and I prefer to do my trainerroad workouts with that because I use my favero indoors and outdoors, and want to have consistency in my power numbers.

However just out of curiosity, I wanted to compare power readings of my trainer and the pedal, but I found a significant difference. The pedal reports on average of 20 watts higher than my kickr trainer. I am not sure who is wrong over here as I calibrate my favero assioma before every ride by using the assioma app. on my smartphone. I the crank length in my garmin headunit and the assioma app. is set correctly to 172.5mm (which is what is true). I use a fairly clean chain and it is not too dirty. Has anyone else had the same issue?

Try it with a dual-sided power meter.

Unfortunately, I do not have one. I tried reinstalling my assioma pedal and calibrated it around 10 times and it still reads quite high compared to my KICKR. I have contacted KICKR and Favero and waiting for their reply.

Depending on how many watts you’re putting out, 20w could be within the tolerances of both power meters including a minor L/R imbalance. It is hard to say without having true dual sided meter readings to compare to.

As an example, I have a Tacx Neo 1, assioma duo pedals and I used to have a stages L crank.

When I compared the Neo to the Stages I was getting around 20w difference. I put the down to imbalance. I was wrong. I bought the duos to check and they were bang on with the Tacx and I didn’t have an imbalance. It turned out I had a faulty crank which was acknowledged and refunded by Stages.

Various vloggers and reviewers will always tell you to compare three power sources to figure out the problems.

Different trainer but I think when I looked two years or so my Suito couldn’t keep up with my Favero Be Pro S . Although I’ve put the difference to the side in my thoughts.

I had a similar issue with dual Assiamo and an older Kickr. Here is the email response from TR customer support to me:

I took a look at your ride, and I could see what you mean about how there is an offset between the Kickr and the power meter. However, to be completely transparent with you, this is actually normal. In fact, it is not uncommon to see trainers and power meters measure differently, with the discrepancy we’re seeing. Since we’re only seeing a 15-watt disparity between the trainer and power meter, the difference you’re experiencing is really good compared to most trainer and power meter combos.

  • As a note, there is not a way to calibrate your Kickr such that its power meter would measure at the same level as the Assioma power meter. The Assioma power meter will always measure more accurately than the Kickr, as the Assioma is a pedal-based power meter, and reads your exertion directly.

  • For this reason, we actually recommend using PowerMatch. The nice part about PowerMatch is, we will send modified targets to your trainer, so that you will be hitting the target power according to the Assioma power meter, instead of according to the Kickr. This way, you know you’re hitting all of your targets according to your Assioma power meter.

  • By using the Assioma, you will have the same source of power measurement for all of your rides, and your results both indoors and outdoors will be more comparable.


As someone who went down this exact rabbit hole six months ago the only advice I can give you is DON’T DO IT. It’s gonna do your head in and you’re not going to get the closure you’re looking for. Your instincts are right. Stick with the Assioma’s. Use that as your metric for everything and be done with it.

On another note, as a part of my rabbit hole journey I upgraded to the Duo’s. Turns out on any given day my imbalance is anywhere from 46/54 to 50/50. That’s an 8% power swing or 24w at 300w.


Interesting… I heard back from Wahoo support who confirmed that my trainer is calibrated and accurate. He then proceeded to tell me that the accuracy comparison between power meters and the wahoo trainer can be more than 10% when considering power loss through drivetrain (jockey wheels included) and combined accuracy of both my assioma and the kickr.

Since I calibrate my assioma before every single ride and the support technician couldn’t find anything abnormal, I can only assume that it is reading accurately and trust the readings. So yes, 20w seems to be within the tolerance range.

I completely agree with this perspective. I spent alot of time using DC rainmakers comparison tool, doing static weight tests on the Assioma’s, etc. If you don’t need dual reporting (ie. not doing competitive E sports) then link your power pedals to the kickr and have the kickr report the power meter numbers. That way you don’t have discrepancies between indoor and outdoor rides.

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My Garmin Vector 3 pedals differ by about 20w from the readings of my Kickr Core.

Since it’s a little annoying to have to switch pedals for every workout, I simply don’t. I use the trainer to guide all my indoor workouts, and use the pedals for outdoor rides.

FTP is just a number. It is useful to the degree to which it enables the TR workouts to be appropriate to your current fitness. As long as the workouts are hard enough but not too hard, it doesn’t matter what your FTP “really” is.


In which universe 20w difference is within tolerances? What machines are those? Tunnel diggers??

PM companies are making fools out of us and we are as a community not standing up. We will continue to pay for random number generators.
When pm guru reviewers test(!) these devices they do it by comparing multiple pms. And expect them to line up. No line up no pass. They have to match, when they do not it is a big bu-bu.
When we do the comparison and got a 15% difference that is a taboo to complain.

  • no pm reads the same
  • add up the tolerences
  • why does it matter. Just ride your bike
  • I never had a problem with that pm
  • why do you need to know your ftp. Polarised is better anyway
  • I raised my ftp from 180 to 210 with that pm

Please stop. Or do not involve the law when I

  • when I price match with barbian dollars. What? It is just a symbol. Why be a stick up about $ sign.
  • pay %5-%20 less. Price is just a number. And this is within tolerances.

The problem with testing power meters is that it’s really hard to compare them to a device with gold standard accuracy, which would probably be some sort of custom-built calibrated torque meter setup that costs $30,000. Basically what they use to calibrate the PM at the factory.

FWIW, my Kickr Core read quite high over my P2M NG ECO until I did a factory spindown (didn’t even realize this until I won my first two Zwift races), which I would have had no idea was even possible except for the power meter / smart trainer blogosphere. Now it reads about the same power. Or at least it did the last time I through my PM-equipped bike on the trainer, in the spring, when temperatures in the Pain Cave were quite different than they are now. According to Wahoo, the Kickr isn’t accurate below 10 C…

What is your source for this? I’m interested to know as I was debating getting a v5 in the sales.

Alternatively just open the favero app and offset the pedal power by the same %. Good for your ego, good for your training (as you’ll have the same numbers inside and out) and no requirement for power match. That is, of course, if it’s a static power % difference.

This is why assiomas should be on the banned list for Zwift.

Try it with a third power meter. If that’s a SRM, it’s likely the gold standard and everything else is wanting. If not, the two that agree most will point to the third as faulty. Right now you don’t have anything tangible to make an educated guess.

Because they are crap or they allow setting the slope?
If latter many pms allow that.

Cancel culture reaches power meters!? :rofl: Most meters these days can be adjusted.

A better solution would be to update the power meter profiles (ANT/BLE/whatever) to include a variable that has the amount of slope change from factory calibration.

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This will get a meter to ‘works in perfect conditions’ levels. I’ve seen a LOT of these setups used to test/calibrate/verify smart trainers and power meters… but when the products are used in real world conditions, they don’t hold up.

Power is really REALLY hard to get right for the end-user.


Wahoo tech support! According to them, it will read high, but they wouldn’t say by how much.

Basically, if you need perfect accuracy, you need a climate-controlled room, and you need to warm the trainer up first.

Right, which is why so many people like me spend so much time fretting about our power sources, since there’s no way to know whether one or both are wrong, even if they align…

That said, you need to at least get them to claimed accuracy in perfect conditions before you can start worrying about real-world conditions.

I sent my first trainer (Flux 1.0) back because the belt came off the big pulley, warping it slightly, which somehow resulted in power numbers that I only discovered were high after getting my first power meter (quite an ego hit). No amount of spindown sequences would fix this, because spindowns probably assume that everything is mechanically in working order.