This was not really a proper training session but the last of my series of comparisons between the PowerTap and the CompuTrainer. I wanted to do a simple ramp type test covering the more commonly used wattage range in 25W steps going from 175W to 300W, riding for 5 minutes at each load setting, The whole proces was controlled by a .erg file in the CompuTrainer. The outcome was that the average wattage for the workout on the CompuTrainer was 225W and on the PowerTap 226W, the 2 units tracked each other very closely though as in previous tests the PowerTap recorded higher and lower very short duration wattages. The CompuTrainer when in ergo mode I understand adjusts the load x30 per second so who knows whether the CompuTrainer or the PowerTap is "right" - but they are certainly close enough over the most commonly used wattages and stable over 5 minute periods. The CompuTrainer calibrations were again checked before and after the test and there was no discernable drift at all. So, you will be pleased to know that that's the testing over!
The graph of the wattages recorded by the 2 units is shown below:
[Uploaded 26/05/2008 18:32:06]