Originally Posted by VT Biker

So here is a question I am hoping someone can shed some light on.

Previously, during this winter, I was taking an indoor power training class, using a CycleOps indoor training. All power came from the rear wheel engagement with the CycleOps trainer. This yielded average power for 20 minutes in two different tests of 235 and 247 watts over a 20 minute TT effort.

So I just purchased a Quarq power meter, and had it put on by a former Pro mechanic (to ensure that the device would be put on correctly. Went out for a ride today, and ended up with a 20 minute average power of 304 watts for my best 20 minute effort. I know the cranks went from 172.5 to 175mm when I switched to the Quarq, but that really should not change power readings substantially.

This substantial increase in power seems a bit off, as I am going to say that for the most part, my performance has stayed fairly consistent throughout the recent months. Some improvement, but nothing like that.

Questions

A) Would it be likely that the CycleOps was understating my power due to the inherent set-up of using a rear wheel engaged to the trainer wheel/sensor?
B) Or is it more likely that the Quarq is mis-reading the power? It was calibrated by the gang in Spearfish, SD earlier this February, and my understanding is that there is no calibration necessary.


What I am trying to do is determine whether I have an issue with the Quarq, or whether the indoor power numbers likely were due to inherent inaccuracies of using a power # from a trainer.


Thanks,
Brad