I have to diagree with Wahoo on this one. The power numbers transmitted over ANT+ are sent using a rolling counter update. So even if you lose a few ANT+ packets, you will still get the correct average power. It will just mean your instantaneous power will be wrong for a second or so.
The list they gave you just shows they know the product is not 1% accurate If a product says 1%, that should mean it works under all these conditions. If it doesn’t, it should be shown in detail in the manual, or on their web site.
I think there needs to be a standard testing/certification setup for all manufacturers to follow. These products are not cheap. Someone is going to get pissed off enough to start broader legal action.
@NickL and @stevemz: The 1h30min@200W in both ERG and standard mode is probably the way to go, will however try to get those assiomas first to get even better datasets. Doesnt sound like a very fun workout, so it better be worth it. I did experiment with resistance mode in TR during a workout earlier, but didnt find anything special.
Oct22, ERG+resistance mode: DC Rainmaker Analyzer
@road_wars: I completely agree with you, I was just quoting what Wahoo-support wrote, and its the same as stated on their website: KICKR Power Accuracy
Did a new workout in Sim-mode/Zwift yesterday, Quarq back to reading +1%, no drift.
Oct30, sim-mode: DC Rainmaker Analyzer
ERG-workout today, back to drifting from 2% to 6%.
Oct31, ERG mode: DC Rainmaker Analyzer
Since I did the excact same workout oct24 and oct31, I tried to compare them, the drift is almost completely similar: DC Rainmaker Analyzer
So I did the 1h30min ERG@200W today, and result was a bit suprising. No drift, but one “power-jump” at 28min, when I did some low cadence out of the saddle and sat back returning to normal cadence. Really dont know what to get from this.
Nov1: DC Rainmaker Analyzer
(I normally do this between intervals, so that would mean I get several similar “power-jumps” during an interval workout.)
The only other thing that I can think of that might be going on is that during the transition from high power to low power, it’s triggering a calibration event but whiffing due to a lack of true coasting. The offset seems consistent within an interval on your Oct31 workout, but gets progressively larger.
@daniebr, have you tried an Advanced/Factory Spindown? This looks exactly like the issue I had with my KICKR '18 for months. It was a bit of a crap-shot, tried it a few times over a couple of months and eventually it seemed to fix things. Although by that time I had already ended up just getting an extra power meter to leave on the trainer bike for PowerMatch…
I wonder. Did the temperature drift in your pain cave when there was power drift? Maybe that is the difference between the drifting and non-drifting workouts?
@mcneese.chad: How would you do that? Just let the Kickr be in ERG-mode, do some fast pedaling and letting it go?
@chidlow: Im not sure how to do that, remember I did this with Snap/Kickr18, but for the KickrV5 there isnt even a spindown-button in the Wahoo-app.
@road_wars: The temperature in room drifts about 2 degrees from about 16 to 18 degrees for all workouts, less for the shortest I guess. So room temperature drifted the same for non-drift-workout-oct28 and drift-workout-oct31. I initially thougt this was a temperature-issue. But based on last workout, it doesnt seem so.
I will however save the factory-spindown option for later.
Firstly I will do a new ride like yesterdays, trying to trigger the “power-jumps” as many times as I can to get a really “drifty” dataset.
Later I will see if it is possible to do a factory reset (this will disable auto-calibrate since that feature is part of the first firmware upgrade) and see if the “power-jumps” are affected by that, as mentioned by @stevemz.
Trying to do this as systematic as possible, and only change one thing at the time.
My guess would be that its getting confused trying to do it’s auto-calibration while in erg mode.
The flywheel is slowing down - because you are lowering the cadence - so the kickr thinks “i’ll do a calibration now” but simultaneously trainerroad is altering the resistance to keep your power on target - messing up the calculation.
Just a guess and if true I would have thought everyone would see it - not just you.
Yup, wait until the power drops and stabilizes in the recovery, make sure to spin 90rpm or more and just coast. I think you will get at least the 2 seconds that seem required. Let the flywheel come to a full stop to let ERG reset, then restart pedaling quickly.
See if there was drift before and/or after the spindown.
This didnt go as expected, some small “power-jumps”, largest “power-jump” is after 1h50min when Im trying to do a spindown/auto-calibration, tried two more spindowns(last one pausing the workout in wahoo-app):
Nov2: DC Rainmaker Analyzer
Im running out of ideas, asked support about how to factory reset(to see if removing auto-cal will influence something), will also try advanced spindown later.
(pausing workout didnt affect coasting time, it was like coasting in ERG-mode, trainer stops completely within 3-4sec)
Asked Wahoo support about a factory reset. That was not possible.
Wahoo support then asked me if I was having issues with my KICKR.
I tried to explain it as good as I could. Last time I was only told that the Kickr is operating within tolerances. This time, they kind of admitted that I was experiencing a issue with my trainer, and based on my description, they said I would need to perform a factory spindown.
I did the factory spindown, and have done two workouts after.
Basically the results was pretty different for the two workouts:
The first one showed less drift than before. PM reading +3% at start, and +4,5% at end, which gives a drift of only 1,5%. (A litte power jump/red flag at 1h14min though)
Nov4: DC Rainmaker Analyzer
The second one looked pretty similar to the old datasets again. PM reading +0% at start(which is the lowest I have ever seen in ERG-mode, seen similar in SIM-mode though), and +4% at end, which gives a drift of 4%.
Nov5: DC Rainmaker Analyzer
At the start of the Nov5-ride I was really optimistic, readings seemed stable, and at a level pretty similar to what I have seen in sim-mode/zwift. But at the second half of the workout there was power jumps/drift again(best seen at 40min and 1h13min).
I have done a second factory spindown now, and will continue testing during the weekend.
My hope is that I can end up with a trainer that has no more than approx 1% drift, and that the difference between PM and trainer should be about the same in ERG-mode and sim-mode. That is at least what I was used to.
The last factory spindown I did (that worked for me to fix drift it seems) was one I did after a workout - much more warmup time than if you just follow the instructions in the app, or ride for 10-15 minutes easy first. YMMV - good luck!
