Power discrepancies between devices

Howdy, I’m having a bit of an issue with my 2 power meters reading wildly different numbers. My indoor trainer (Elite Suito) is typically reading 30-40+ watts higher than my Stages device on my outdoor bike. I wouldn’t care so much as long as it’s consistent, which it is, but if I have my FTP set for my indoor device and then use Outside Workouts on my outdoor device, the numbers will be way off.

Does anyone have any feedback on this or any way to adjust one or the other so that they are a closer match? I’d also like to know which one of them is actually accurate since the discrepancy is so great, it’s kind of hard to truly assess my fitness.

Thanks in advance!

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  • You entered the lovely and sad world of having more than one power measuring device. As great as having them match and be within manufacturer tolerances, your experience is all too common. There are numerous threads here with people that have mismatched devices.
  • Some power meters allow adjustment (scaling of value in the case of the Favero Assioma), but I don’t think you have that option with either of your devices directly.
  • One hack, mentioned just today in another thread, is to adjust your crank length setting in your power meter to fudge your numbers closer to your trainer (which I don’t think offers any means of adjustment, even hacks like the length fake above).

That is essentially impossible without at least a 3rd power measuring device to compare between your current two.

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Is your stages a left side only, or dual side? If it’s left side only, then it’s possible your left leg is weaker than the right thus causing the stages to appear lower overall.

One of these days, I need to write and FAQ on “Why don’t my power meters / trainer match?”. There are many factors that are potential influences, and single-sided is definitely one of them, along with maybe half a dozen more.

Power Device Data Tolerances, Zero Offset or Calibration, Power Measurement Location, Single-Leg vs Dual-Leg vs Combined Power, Non-Round Chainrings, Trainer Accuracy at Various Flywheel Speeds, etc.

I should also crowdsource some info with requests from guys like Ray and Shane that have a better depth of knowledge here.

Quick google results:

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Thanks for the help! I will try those little hacks to try to get them to read closer to one another.

Shoulda boughta SRM…

Have you tried statically calibrating your left-leg-only power meter?