I have recently realized that the power values estimated by my trainer (Tacx Flux) are way off the values measured on my pedals (Favero Assioma): trainers shows around 10-12% more power than measured at pedals*.
I would like TrainerRoad developers to add a feature that allows us to correct estimated values coming from the trainer. Nothing really fancy: just a proportional gain that you would define on your connected device.
I find a bit frustrating that power values are not really comparable/consistent between riding indoors and outdoors because of such a significant (at least in my setup) difference.
The more users interested on this the higher the probability that it gets in some future release.
Anyone else interested on this?
Regards,
Carles
*without considering the fact that power at pedals should be greater (2-3% as I have read somewhere) than at the wheel because of the transmission losses
Are you calibrating the pedals and the trainer before each ride? I had a consistent difference between a SRAM crank-arm meter and my Kickr Core, after several dual-recording rides I decided to use the slope-adjust feature on the SRAM meter to bring it in line with the Kickr, since you can only calibrate the Kickr with the spin-down feature.
Make sure crank length settings are correct for the pedals.
But, if that’s not it, you can use PowerMatch and have TR use pedals as your power source.
It would be nice if you could adjust the slope for the trainer like you can on a Quarq or do a permanent offset in the TR app for your trainer so you didn’t have to leave a second Power Source hooked up though.
Tacx can only be calibrated with the spin down calibration.
Favero allows user to calibrate the measure of the applied force on the pedal with a known weight. I trust more this calibration way than the one used with the Tacx trainer (once you correctly measure the applied force on the pedal it is pretty straightforward to evaluate the generated power).
I will have a look at the crank length settings in the Favero App but I don’t think that is really the issue (the value should be really off to explain the huge power values I get).
It is for me not an option to either leave the Assioma on my dedicated indoor training bike or to mount/dismount them every time I ride indoors/outdoors.
The value does need to be accurate, or it will give you incorrect readings. So, it needs to be re-set every time you put pedals on a bike with a different crank length.
You can set it in the app. But I think it is also set within most head units so the setting in the headunit can override it. Check that to make sure it’s correct too.
The TR App doesn’t have the setting, so I believe it would default to the last used, or what’s in the app, not sure.
If that all checks out - just trust the Assioma’s, and use the TR power match feature to use the power you get from the pedals, and ignore the reading from the trainer. If you refuse to swap pedals - your other option would be to adjust the reading you get from the assioma until it matches your trainer, using the trainer as the source of truth (Or, get a new trainer or another PM like a quarq for the indoor bike)