@daniebr I haven’t done a factory spin down yet, mainly cause I was under the impression you didn’t have to anymore, as well as it being aligned well at the start of the ride, so it seems to be drift in either the Kickr/Assiomas/both.
Based on the consistency reported in here I assume Kickr, but maybe will pause ride and re-calibrate pedals next time as an experiment as well.
@therhino: After doing factory spindown post workout (warm kickr), my PM readings start low and aligns well with Kickr within about 40mins. Then they are aligned for the complete workout. Before I did factory spindown readings where aligned in the start of workout, but ended up at +5-6%. I was told by Wahoo support to do a factory spindown after they “reviewed” my data.
After purchasing the Assioma Duos and confirming they read superclose to my Quarq, Im about 100% sure that its the Kickr that drifts not the PMs. The temperature rise during a workout is much higher for the Kickr than my PMs, so that makes sense. My Quarq didnt drift vs the Neo 2T I had earlier either.
It is possible he has done other testing/did a longer warm up before he started recording aswell. Allmost all of my drift seems to happen during first 40-ish minutes…
Same. Just a shame that most of my workouts are an hour so the thing is drifting for 2/3rds of the time.
I would always trust the Assioma over any trainer with an optical guessing gauge. Hell, I’d probably trust a single sided Stages over most trainers too
FWIW my H3 drifts compared to pedals. First 15 mins it reads higher, then comes back down, and after an hour reads lower
After I bought my Assiomas I see that my L/R balance varies “a lot” during hard intervals, so a single sided PM probably wouldnt fit me personally. I also see that my L/R balance from Quarq is pretty off. But yes, I would also trust a PM more than a trainer, exception is maybe the Neos that seems very accurate as long as flywheel speed is not too high.
@daniebr How do you do a spin down on the v5? Don’t see it in the app and googling not helping much.
Thanks for that. As an experiment yesterday I tried setting the “Control with ANT+ PM” directly in the Wahoo app and still had the drift over the ride. That is a hard one to reason about.
My v5 appears to go opposite to the trends noted here. Did a 1hr 6 x 6min SS session this week (Monitor).
The first block, 10 minutes in had Kickr reading 0.6% over my Quarq.
Last block, 50 minutes in, had the Kickr reading 2.0% over the Quarq.
I also had Powertap P1s and they were pretty consistently 2.3% out from the Kickr from start to finish. i.e. if anything was drifting it was the Quarq
If only they included a warm-up mode that would get the trainer up to operating temperature before you started your workout.
So I dug into this a bit last night on a workout. While only an hour, virtually every post in this thread shows drift by the 40ish minute marker, so I figured I’d at least see something there. Short version: Zero drift during the test (Slide Mountain -2)
Here’s the data set: DC Rainmaker Analyzer
Setting aside the complete dropout festival that happened between the SRM X and FR745 on the first interval, or that it was oddly lower than the rest - there was zero drifting differences between the KICKRv5 and the Quarq DZero, or even the SRM-X (again, ignoring the dropouts/offset).
For this test I did no warm-up and no calibration of any units, nor did I ever stop pedaling (as to not give the KICKR a chance to auto re-cal). From a gearing standpoint I was small ring up front, and almost the easiest ring on the back. Temperature in the DCR Studio was constant, at about 73F/23C according to the Edge device on the table. This is on the latest production V5 firmware.
Thanks for looking into this Ray.
My kickr is super consistent drifting with respect to my faveros over the course of a workout. Not by much - it might start 1% higher and end 2% lower - but the trend is always the same and always there.
I must admit that I always run my TR workouts in the big ring up front so the thing I’ll try next is doing a workout with easier gearing…
One thing I would note in your data @dcrainmaker is that while the offset between your wahoo and the quark is clearly acceptable throughout - you are getting a drift in the same direction that I and others experience.
The first interval in your data shows the kickr at +1.2% and the third at +0.2% with the second interval around half way between at +0.5%
I 100% agree that this is fine - but what I am going to try is:
My predication is that my unit might perform at good as yours when the experiment is replicated but will get worse when I increase the watts and/or flywheel speed.
Thanks again for looking into it.
Yeah, I think drift at 1% and under would be acceptable. One thing though to keep in mind is that I purposefully didn’t re-calibrate either the Quarq or SRM (or KICKR), as such, we’re just as likely seeing the Quarq drift/temp shift as well. The last time I would have ridden this combo was about 15 days ago (was using other smart bikes during this time), and we’ve been in a cold snap so the DCR Cave temp would have definitely shifted (it’s just a giant warehouse and floats constantly).
I’ll do my next workout at a higher wattage for sure. My legs were somewhat shot yesterday and this was the mental compromise I made. 
So, I have now been able to do some more testing on my new trainer.
(All on newest firmware, small chainring front, mid cog-ish on cassette)
So from the start my new trainer reads about the same as my old one in the start (+2% to +6%). My old trainer stabilized with PM reading about -2-3% in the start and allmost identical at the end. I have been doing factory spindowns after each ride except last one. The dec23 and jan11 rides are the one that are most similar to where I left off my old trainer, what they have in common is that the rides before (dec22 and jan9) where long rides.
I have had limited time lately, so the length of rides have varied. Last dataset was pretty nice, so think Im gonna skip the spindowns now and see how it acts. If im gonna do more spindowns I will do it after a long ride.
To summarize I would say that the new trainer drifts similar to the old one. Drifts seems quite consistent, level of over/under-reading seems to vary with length of ride(temperature of trainer?) done before doing factory spindown.
Are we? Im guessing my Quarq/Duos maybe gets a couple of degrees hotter during a workout(temperature of the room), but my Kickr flywheel starts at maybe 18-20 degrees and end up at maybe 60-80 degrees? Im just guessing here, but it gets really warm.
No, I’m referring to the fact that the Quarq algorithm has to temp-adjust when it first turns on. Since my Quarq had been sitting for almost two weeks, I have zero idea what the temp was back then.
Most power meter companies will take about 10 or so mins to temp comp, because they want to avoid scenarios like going through a short section of hot pavement being picked up by the temp sensors (via air) but not yet impacting the strain gauge on metal/carbon properties.
Ah, I see. I calibrate both my Quarq and Assioma before every workout, they seem to be very consistent. Anyways its winter here in Norway so the bike/PMs is allways indoor and temperature is pretty stable from workout to workout.
Anyways, appreciate your effort, allways nice to get input/data from one of the legends in the game!
Do you have an older Quarq that doesn’t auto-zero?
Nope, it’s a brand new DZero. But the autozero algorithm only works when it’s turned on, and the dynamic temp compensation also only works when powered on, and thus both of those have to turn on and stabilize (which takes about 10 or so mins for most power meters to smooth the temp readings, as to avoid issues with briefly transient air masses of hot/cold air).
