Power Data Comparison

Thoughts on this comparison between Quarq D Zero on Zwift, Favero Assioma Duo Garmin and Wahoo Kickr 2016 in wahoo app.

I use the @dcrainmaker analyzer tool on many of my TR rides with the same equipment models as you. I don’t typically record my Kickr output, so I can’t compare that.

For a brief bit after upgrading my Assioma pedals to the latest firmware they were ~20-30W away from my Quarq, but after charging / changing crank length from correct value to new value and back, and zeroing with the app, things seem closer and consistent. My Assioma’s tend to read ~5-10W lower than my Quarq in the 300W range and are slightly closer in the 150W range (but still lower, maybe 3-7W).

Your comparison looks pretty close to me, from these plots. I’d look closely at zoomed in areas of interest and monitor it over a few rides to see how consistent these results are.

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I’d say in general that looks pretty darn close. In theory the Favero’s should read highest, then the Quarq, then you’re KICKR - with the biggest jump being between the KICKR and the others, due to the drivetrain losses. In most cases that’s 1-2%, perhaps 3% if you’ve got a dirtier drivechain.

The slight separation at the 10s mean/max graph isn’t ideal, and might imply some quirk going on with the Favero there. But you’d have to dig into things a bit more.


Thanks Ray!


Any ideas on this?? I get the overall difference of 1-2%. But what is up with the Vector 3S pedal reading LOWER for the first 10 mins until the first couple of sprints? Wondering if the hard efforts “woke them up?” And if I hadn’t done the sprints, would they have read lower for the entire workout?

Thanks for any advice!

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Hard to say exactly. Possible scenarios:

  1. You’ve got a left/right balance shift (your body) that takes a bit of warming up to account for. Left/right balance shifts over time are totally common, though I usually see it much later in fatigue states (like, 5 hour ride in the mountains).

  2. A rare temp comp scenario where your room/etc shifted heat faster than Garmin temp compensation algorithm.

  3. A build on #2 where you did a zero offset at a significantly different temp than riding the workout, and then it has to catch back up. I was talking with Garmin years ago about this sort of scenario where in the winter you walk outside with your bike - is it better to zero offset then, or 15 mins later? And which scenario is ‘better’ for those 15 minutes of data. They said taking the bike from hot to cold and immediately zero offsetting at 0 mins was actually way worse because things weren’t caught up yet. Versus if one just let everything roll together, the ‘system’ would roughly stay happy together as it cooled (or heated).

  4. Finally, since I didn’t see mention of which trainer this is, it’s also far more likely it’s just the trainer warming up. I find about 15 minutes being the perfect warm-up for most trainers, including the ones that pretend they don’t need warming up. The only exception to this is really the Tacx NEO series, which legit doesn’t need warming up. Everyone else seems to exhibit at least some temp shifts (however minimal).

Anyway, it’s always hard to tell with left only units on accuracy, especially when it’s just within a few watts.

Wow, thanks so much for the in depth reply. Greatly appreciated. The trainer is a new Wahoo Kickr. The warming up sounds like the most likely, I wasn’t aware of that. Although, maybe a visit to the local osteo is in order…