I'd like to know the same thing: how accurate of an estimate is the power calc spreadsheet compared to a Powertap? If you could perhaps post the powertap figure you hold and what your combined weight (bike & rider) is, what mag setting and speed your holding on the e-motion roller I can figure out what the calculator predicts. I'm looking for something in the mid 100's power range and something in the low to mid 300's power range (on the PowerTap) to see how closely the spreadsheet estimates.
Thanks in advance...