Powertap P1 out of whack - straight to the bin?

I recently built a new bike and put a pair of P1 pedals on it, I had them laying around. After a test ride I noticed that RPE completely didn’t match displayed wattages - I went into a full DC Rainmaker mode and did some more testing against my other PMs - Quark, Stages, Power2max. It seems like the pedals are consistently reading 50-70W lower. Zeroing etc didn’t help. Crank length is set up correctly.

With Powertap being canned by Sram, is there anywhere I can perform recalibration or is the only option to write these off?

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Just to validate, you using ANT+ or BLE to connect (and to what head unit), and then from there, any chance it’s only recording one side?

That can happen over BLE with some head units, which might match why it’s reading a fair bit lower.


ANT+ for all connections - one sided P1s vs one sided Stages, then I also sense checked vs double sided quarq and p2m on other bikes. Stages/quarq/p2m are very close, P1s is way off.

I used Edge 530 and Edge 520 to record the data from both units at the same time (I accidentally paused the recording on the 520 at the beginning, not quitting my job for hardware testing anytime soon :slight_smile: )

Stages file:

P1s file:

Ick. Then yeah, especially with one-sided, that should be good alignment.

I’m going to assume you’ve done a zero offset? Also, for fun, reset the crank length. Meaning, set it to 170mm (and save/exit that menu), then go back in and to whatever your crank length is (e.g. 172.5mm).

Just in case for some weird reason the crank length is stored as something like 120mm or whatever.


Yeah I’ve done the 0 offset but will try your tip with resetting the crank length and report back. Thanks a lot!

If you’re in the UK I might know a guy who does maintenance on those?


I’m in the Netherlands but have family in UK and go there often so that could be an option… I’ll try Ray’s suggestions first and if that doesn’t work I’ll send you a message, thank you!

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Well, it worked! Thanks a lot Ray, I did a test ride again and there’s only approx 2% difference between Stages and P1s but it’s pretty consistent now.

Resetting the crank length did the trick (from 175 to 170 and back to 175).


Woot, awesome!