2019 Kickr vs Stages power discrepancies

Hi All,

My 2019 Kickr is reading 30 watts lower than my single sided Stages, I’m sure this has been discussed ad nauseam, but I am currently losing my mind.

I have done several factory spindowns on the Kickr and the stages is calibrated, removed the wahoo app, reinstalled. Firmware is up to date.

This is my 2nd Kickr and this one just seems off. Wahoo support has been less than helpful, telling me the kickr is fine and its within tolerance. Which seems insane to me because Kickr states on their site +/- 2% power.

I understand there are some discrepancies between hub based and crank based power. Knowing that, I just put on a new cassette and chain on to no avail.

I know stages can be generous with their power output, but this seems way beyond generous.

This is the same ride, using the kickr and the stages. 30 watt difference in average power?!?!?!
Screen Shot 2020-02-25 at 6.47.39 PM|365x314

did an additional test with the kickr and a different bike with a Quarq…and got the same 30 watt power differential, with the kickr reporting 30 watts lower.

anybody have this problem or any solutions?! I am losing my mind, I paid a lot for the kickr and would like it to function as intended and wahoo support seems to have written me off.

thanks!

You can analyze the two files on zwiftpower, that might show the comparison better to see where the power is off track. Just comparing averages doesn’t really tell the whole story.

All power meters will be somewhat different. There could be power loss in the drive chain when comparing crank or pedal based power meters to hub based or smart trainers.

That’s helpful, thanks Mike!..using DCRainmakers analysis tool now, will check zwiftpower out.


I should have clarified that the power on the Kickr is consistently lower.

seems like the Kickr drops out completely, which clearly affects the overall average.

I have the same issue with an older Kickr and my Stages left crank PM. I recently got a pair of Favero Assioma pedals, and guess what…

The pedals agree with the Kickr.

So, I have to believe that the Stages is wrong.

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Now that I’ve read more carefully, I see that you appear to have agreement between your Stages and Quarq, with the Kickr being the lone dissenter.

Paraphrasing Segal’s Law:

A cyclist with one power meter knows his/her wattage; a cyclist with two is never sure.

Perhaps there’s a corollary:

A cyclist with three power meters has at least one that is defective.

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if only wahoo customer support agreed with Segal’s law :confused:

I just realized why my Stages reads high. According to my Assioma pedals, my power balance ranges from 54/46 to 57/43. That means my left leg puts out 20% to 30% more power than my right. Since the Stages only measures left leg power and then doubles it, the Stages reads 10% to 15% high.

Yeah, I’m starting to think that the one sided Stages is probably not the best in terms of precise accuracy. I always assumed my Right leg had the dominant power, but who knows?

Thanks Jim

I think this needs amending to say:

A cyclist with one power meter thinks they know their wattage