Favero Assioma Duo and KickrV5 watts discrecpacy

Lately I have been using both Favero Assioma Duo on my bike as well as with the Kickr5 indoor.

I should note that both devices are on the latest firmware available and not damaged in any way to my knowledge. Auto reset/calibration is turned on for both, so that they should be spot on all the time.

Lately, I did notice, that if ERG mode is turned ON (I actually did not test yet with erg mode OFF) when using Zwift there is a constant but noticeable difference in the amounts of watts measure, where the Assioma Duo measures almost precisely 10 watts more than what is displayed on by the Kickr5 on Zwift.

Did anybody else notice such difference? Certainly a lot of people online did experience similar issues in the past with much greater differences, mostly due to firmware issues that seem to have been fixed, or so they say.
I can’t explain this myself, but if anybody has encounter the same issue, has an explanation or knows what causing it/how to fix it, I would love to know!

For the moment I have set my Kickr5 to use and external AntID device (my pedals) if available. At least that way I will have a consistent, although possibly high, watt measurement when training inside and outside. For the moment that seemed to me the only reasonable thing to do.

Thank you all!

Yes, that’s consistent with my experience, 10-15w difference. Some is due to drivetrain loss. My trainer bike uses the KICKR. My roads bike uses Favero. Before I had two bikes – I just took the differences in account. Of course, it hurts your Swift racing. :slight_smile:

Did you try to get in contact with either company?

Doesn’t it make more sense to stick to the same one just for sake of FTP consistency?

No. I attributed it to drivetrain loss 3ish% and the KICKR accuracy of +/- 2%. I take the Assioma as the standard.

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It does make sense but I only have one set of power meters. They stay on my road bike while my other bike basically stays on the trainer. Don’t want to swap them every few days. :slight_smile:

So just to double check and make sure I understood correctly, you reckon that the fact that the Kickr measure watts at “wheel hight” causes it to be lower as a certain amount is lost from power transfer through chain, cassette etc?

Do you adjust your Zwift ftps to account for that?

Sorry for the tardy response. Yes, there is a loss in the drivetrain between the KICKR and the pedals. If you are having Zwift measure power from the Assioma and controllable at the trainer then you are fine. That is the way my wife’s bike is set up (although the previous update broke that ability). Since you are using the bike with the pedals then this is how I would set it up – power and cadence reading from the pedals, controllable at the trainer.

If you are reading power and controllable at the trainer, then you have to do some, at least mental adjustments that you are happy with.


I will definitely test that next time and let you know!

And no need to apologize at all, you have been super clear and super helpful! :grin:

:star::star::star::star::star:/5 for you hahaha

For the record, I have come across the same situation on other trainers as well (Elite Real Turbo Muin B+ and Elite Direto XR). For the first one, it was so much out I had to use Power Match (e.g. use pedal reported power to adjust the resistance on the trainer) but for XR and my Kickr V5 I just use what the trainer reports.

It does make indoor training a bit tougher and especially the transition from Sweet Spot outdoors to cx-intervals indoors is a pain… 10w difference with my dad-watts can lead to not being able to hold the watts.

How have you others sorted this out as there is no “indoor vs. outdoor FTP” but there IS a Power Meter 1 (e.g. pedals) and Power Meter 2 (e.g. trainer) FTP… How are we to FTFP when the world doesn’t comply :smiley:

If you log into your Wahoo Fitness app (the black, not the blue one) and select your trainer, in the settings you can select to add an Ant Power meter when available so power readings will come from the pedals but the kickr will still control the resistance!



I’ve had SO many different power meters (SRM, PowerTap, Rotor, Favero, Wahoo KICKR, whatever’s on my mtn bike, etc.). I’ve never gotten two from the same brand to always agree! (I usually have 4-5 of the same brand at one time). They’re really no different than trying to get bathroom scales to agree, thermometers to agree, etc.

Consistency is what’s important. I achieve that by only letting Zwift use my KICKR for sending the course info to me. The power and cadence come from my on-bike power meters. That way I experience the same power readings as when I’m on the road. Yes, I calibrate everything, but I’m not extremely analytical because I know they are going to disagree. By the way, even if they are perfectly identical, the fact that they aren’t synchronized on the per second measurements means that real-time power will differ.

My personal opinion (JMHO) is to always use the power on your bike as your measurement and stay consistent.



Today I have just found out something really interesting. If you have your wahoo turned on while you are doing a training session in ERG mode on Zwift using your Kickr and the same Wahoo device also has the same kickr added to the list of possible devices available it will try to connect to it throughout the ride (disregarding the connected assioma pedals and the fact the Zwift is already using the Kickr) causing spikes in your power resistance.

A bit unrelated to my initial question perhaps but still…