First the good news: The Polar CS600 power kit (in it's newest production runs!!) seems a lot more stable than the S720i - including on turbo trainers. I found the S720i unit suffered from all kinds of interference on the trainer, whereas the CS600 gives credible data.
And now the bad news - or is it?? I'm noticing that although work in Coggan levels 1 - 3 seems to be represented well by the CS600, level 4 - 6 workouts give higher power outputs than expected (judged against RPE / gearing / cadence / years of experience etc). The trainer seems to be in the order of 10 - 15% above what I would expect.
I'm using a very simple Cyclops wind trainer...no calibration (other than using coastdown time)...but to me L1 - L3 'feels' like the road and L4 upwards feels too easy for the numbers I'm getting.
I know I'm not the first person to note higher power readings on the trainer as opposed to the road - and this has been observed by riders using a range of power meters, so it's not a Polar anomaly.
My question (and I'm happy for this to be shot down by all the scientists out there!!) is: given the energy required to control a bike on the road (and presumably the larger number of muscles involved) does the fact that the bike is locked/stable on a trainer mean that more power gets directed via the drivetrain? Has any research been carried out into this?
Of course, it doesn't affect how much power a rider can produce...but it might explain why we see more of it in whichever bit of the drivtrain our power meter measures?
McP