Got Powertap P1? Different crank lengths? Wahoo Elemnt?

Ok I think this might be as special-snowflakey as it gets, but here we go! I think I found a bug.

I sent my P1s off for a warranty repair because they were being flakey, showing me a big imbalance (8%) where there used to be less than 1% on average and one pedal always seems to have reset to an incorrect crank length setting no matter how often I reset it in the Powertap App (my roadies have 172.5mm cranks, my TT has 170). See here for that: Powertap P1(s) PSA: Use the SRAM AXS app

The service centre did find a small issue where one diagnostic value was slightly out of the optimal range and they told me about using the AXS app, that my firmware was out of date, so I thought one or more of those must have been the problem.

I got them back today, decided to check them by running TR + Kickr on my PC while recording the P1s on my Elemnt. Reported the same imbalance as before, 54/46. I’d verified their settings (172.5mm) and calibration in the AXS app before I started.

Turns out it was the Elemnt. Way back in the mists of time I set the crank length in the Elemnt app to 170mm, forgot about it, now every time I calibrate the pedals in the Elemnt it sends one of them this fossilized value! I reproduced this a few times before contacting Wahoo support.

How’s that for a weird gadget ecosystem problem?

Yep. The P1/P2 are dinosaurs now. They’re true L/R over ANT+ but over BLE you have two independent P1S/P2S units. Could it be that the Elemnt was pairing via BLE and only sending the crank length to the single pedal?

Power pedal crank length setting can be a PIA. A head unit will override what is set on the pedal. Head units that don’t set crank length (most indoor training software, iirc) need the correct setting in the pedal.


Good shout! I did wonder that yesterday while I was playing with it and it was listed as ANT+ in the Elemnt. I get left/right balance which I assume is only available over ANT+ given that TrainerRoad only gets single-sided over Bluetooth. I’m none the wiser what it’s doing under the hood with pairing, mind you.

Actually that reminds me of something else. If I zero the pedals individually in AXS I get significantly different offsets for each (difference of about 10), but if I calibrate with TR, Elemnt or Garmin I only see the left value. I assume they’re all zeroing both, but showing a single value.