My bike power meter is about 12% off - how to adjust TSS to match actual effort?

As the title suggests, I know my crank-based power meter reads about 12% lower than my smart trainer. This is fine, the offset is consistent, but it makes for a wonky TSS chart.

Yesterday, I completed the equivalent of a TR workout, whilst riding around a local track. Instead of hitting the TR power (277) I was hitting the equivalent power target on my bike (e245W). I know I got all the benefit out of the session, but my calendar records that I did a much lower effort ride than I did.

Is there any way to automatically adjust a power meter’s data?

You have it backwards. Your power meter is most likely correct and your smart trainer is most likely reading too high and inflating your tss.

Best thing to do is use powermatch so that your power meter is controlling your trainer.


If you have a 4iiii power meter you can adjust it to match your trainer.

What about using power match so you drive your trainer from your power meter and have one source? I agree that it’s more likely your crank PM is more accurate than your trainer.

What PM do you have?


I have a Stages 2nd gen left-only crank power meter, and a Tacx Flux. I know the Stages is incorrect, because my power over the same course dropped over a year, despite my speed going up.

I did a 17km TT shortly after I got the power meter, and it read with an average power of 295W. The next time I did that event, a year later, it read 253W, but I was a bit quicker over the course, in worse conditions. I have since taken over a minute off my PB, and still only read 265W average.

Could be weather or improvements in aero account for reduced times despite less power

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If it’s messed up like you think send it in to get checked out. Regardless of whatever you use find something and stick with it.

My kickr core was reading my seated sprints at about 200 watts higher than my quarq was (before I moved it over to my new bike). I really liked that higher number, but as soon as the quarq went on it was back to the numbers I was used to seeing.

To me power match is what needs to be used because I’m not getting my kickr to do power on my outdoor rides but I will have my quarq.

Let me ask, if the other pm was reading higher would you care/think the trainer was reading low?

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Everyone likes the bigger numbers! I this case though, I have a similar effort to compare it to, so I can confidently say that it has changed.

I would trust the Stages.

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If you want to use your Stages as your main and repeatable power source record your workouts on a garmin or similar as well as on TR. and save the fit file. Use and change the power by 12%, re-save and upload to TR, not forgetting to delete the original workout. Your TSS should be more representative. If you want your Tax to be your consistant power source just do the same for your outdoor rides.

Are you calibrating your Stages and Flux?

If you still just want to change the TSS after reading all the suggestions I wonder if you could just change your weight on the bike computer?

Weight is not a component of the TSS calculation.

Another way would be to edit your FTP in the Edit ride facility on the individual rides which would bring your TSS in line.