I’ve had quite a few Quarqs by now and this year I bought a Sram Red Quarq. I have seen two potential problems with it and I’m curious of what others make of this.
First there is a pretty big drift in the zero offset. Every ride it’s 30-60 points lower at the end than at the start and at the start of a ride it’s always around 10-30 points lower than it was at the start of the previous ride. This is regardless of temperature. During the 3months I’ve used it zero offset has gone from 150 to -700 and it keeps going down. I used a Riken a few months before this which was quite stable and seemed to be both precise and accurate. The new one does not however.
Other problem is that every once in a while power jumps suddenly for the same effort. This again without any temperature shift or a zero offset done right before the power increase. I have especially one file where this is very obvious to me. I did a few out and backs on a small stretch of road and after the first leg the power suddenly increases by almost 150w for similar speed(comparing the two legs going the same way).
What I’ve done is tighten the bolts several times over according to spec. This temporarily raises the offset slightly but then it starts drifting similar to before. Upgraded firmware which I need more time to evaluate any changes with but seems like the zero offset keeps drifting. I have also contacted Quarq customer service and sent them the file. They don’t seem to see any problem with it however, which seems very odd to me(I can send the file to anyone who wants to have a look at it).
I don’t know if the two problems are related but the main thing that bugs me is the zero offset drift and mainly that a certain power doesn’t always feel the same with this one compared to for example the Riken and some other power meters I’ve had. Any input?
I am not sure this will help with the red, but firmware 20 and later made a huuuge difference in reducing drift.
I have rode with a Quarq against PT and Quarq against computrainer. Without FW 20 I was consistently 12 watts higher on the Q than the CT or PT. They are all now within 1w.
FW20 and a manual (back pedal) zeroing after about 15min gives very accurate numbers.
I used to be 12 watts better, but at least now I know they are true watts
I have sent you an email through our support as well but the ride file was misread. I was under the assumption that the first interval was a warm up and the other three contained the data in question. Please let me know via thinkfast.com if there is anything else we can help with to have this taken care of.
FWIW: Both of my Quarq Red units settled in at around -750. After I touch the chainring bolts, I do a bunch of max effort stomps and it seems to get rid of 99% of the ZO drifts associated with new installs. I usually try to do a dozen iterations of 5s @ 1000w, checking the ZO before and after each one. You can tell when it settles out.
I’ve had a similar experience with my Red Quarq. When I bought the unit, offset was ~320-350 and my power numbers were much higher than I was used to seeing on the Stages it replaced. Fair enough - it only needs to be relative to itself. Well over the few months I’ve had the PM the numbers have slowly dropped and dropped. Usually in 10-20 pt increments. I just did the firmware update to allow usage without a magnet (in case mine falls off) which moved my new “zero” to +60. Over the last week since I did that firmware update the zero has been creeping down again. Yesterday before my ride it was 17. It just seems odd.
I’ve also had a couple spikes on rides - usually after a mid-ride recalibration (backwards pedal 4x). The 3 times I’ve had it happen I ended up restarting my garmin and hoping for the best.
