Major difference in power between Wahoo Kickr and Garmin Vectors - please help!

I’ve borrowed a pair (dual sided) of powertap P1 pedals to compare my kickr too, and they show similar results as I have had with the Assiomas. The ride this morning was one of the most obviously off that I have had, as the drop in resistance was very noticeable when it happened at about 15 minutes in. For this ride the kickr varied from +17% to -5%. It does track fairly closely for some sections as well.
Trainer was warmed up and spun down before this workout, and pedals were calibrated as well. Garage was about 62f, so heat should not be an issue.

DCR analyzer link:

Again, like with the Assiomas the L/R track relatively well, so since each pedal is measuring power independently, this is really 4 power meters agreeing that the kickr is wrong. I’m going to file another ticket with Wahoo to see if they will acknowledge a problem, or if I’ll get more of the 'there are lots of reasons for these differences that have nothing to do with us" response.

@GPLama @dcrainmaker Have you guys seen behavior like this on a kickr? (mine is a '16 model) I’m not optmistic that power match will work well with this, as the error varies so much that it will complicate the tracking.

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Kickr 2017 wheel-off / direct drive, comparing to Stages gen2 left-only, and Stages gen3 left/right. I’ve seen mixed results, including some like you’ve posted above.

While the Shimano crank isn’t best for a power meter (per GPLama and others), just another reason to use power match and have one source of truth in my opinion.

Nope. Looks shagged. Given you’ve performed more testing indicating the on bike power meters are ok, all eyes are on that Kickr being a Shitr. If it hasn’t been mentioned already - Aim a fan directly at the unit to keep it cool and test again. I have a suspicion it’s heat related… then again it could be something even more obscure.

Wahoo Support should be all over this as an interesting challenge to solve.

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Yeah, as Lama noted, that definitely appears to be something amiss with the KICKR. I don’t think I’ve ever seen something that dorked up though (from any unit/company). Specifically, the type of dorking rather than the offset per se. Meaning, it’s just super random. One second its fine, then it loses the plot.

Agree that Wahoo support is the way to go here, especially with as much data as you have. I wouldn’t be surprised if given the data you have assembled they just ship ya a new unit without any argument.

As for my smoothing preference for graphs/etc, it honestly depends a bit on the exact ride type. For outdoor rides I’ll usually do 3-5s for under an hour long, and do around 10s for hour+ rides. Otherwise it’s just hard to see on charts. For SIM style (normal Zwift), I’ll usually do 0-3s at most. And for ERG workouts I don’t typically apply any smoothing. Again, all kinda depends on the situation. My goal with adding smoothing in charts is usually just to make it easier to see disparities. If there’s a lot of shifting power (like a race), it’s often hard to see those differences without the tracks being smoothed a bit.

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I reported to Wahoo a year ago and they didn’t care. Easier to point to the other power meter and say “not our problem.”

Nice work! I’ve speculated on this before. Interesting to see that you’ve measured a difference.

FWIW, I think the Assioma pedals are measuring accurately, and others are off.

As I mention in one of the posts below, a similar issue arises with oval vs round chain rings.

Ironic that we all think power meters bring an objectivity to measuring our work effort, whereas we may sometimes be fooling ourselves and RPE is more accurate!

Can anyone recommend a torque spanner for installing Garmin Vector pedals? I can only seem to find Torque Wrenches online?

Ah right, i need a crow foot wrench adapter. Any good quality torque wrenches people would recommend? Paying £100+ for a Park Tool kinda hurts. Especially as it appears I need two? One for sub 10nm stuff like seat posts etc, then a 10-50nm tool for pedals etc?

Damn cycling sucks money out of you…

Clickers are convenient but you need to mind the calibration. For cycling beam type wrenches are fine and always accurate.

I use clicker primarily for high torque stuff, like on a car, where it’s hard to hold 70 lb-ft and go look at the gauge.

Also, you need a torque wrench in both directions, some only have it on the normal tightening rotation, so reverse threaded stuff is just a normal ratchet.

How often do you need to do a factory spindown?

When Wahoo support tells you? I don’t know.