Just started using my quarq on my racing bike. I also use a powertap on my training bike. I was told when I brought the quark to expect an increase in power reading of approximatly 7w compared to the Powertap. However after several field test using both Pm's together the quark reads 10-15w lower! Both were calibrated (zeroed) prior to tests. Has anyone else any experiences with the two types of powermeters and the diferences in power readings?

From memory the standard racing bike drive train is approximately 2-3% efficient. So to be out by approx 7watts that would be at approx 200watts output, which is entirely realistic.

Next up, if the CinQo is reading lower, then something is wrong with the calibration of one or both of the power meters.