Monday, November 09, 2009

Trainer vs. Road

Ok - this is a work in progress. I don't have as much data as I'd like to have, but the general trend is clear. The problem with collecting additional data is that my aerobic system is improving, which makes establishing a true best-fit line a little like trying to hit a moving target. But you'll get the gist of it. The magenta line is a best fit for trainer data. The red line is a best fit for road data.

The not-so-surprising result: it's harder to ride the trainer than to ride on the road at the same power (all the power data was collected using my Power Tap). For now I'll target my training zones on the trainer using a target heartrate along with the trainer curve to get a target power range. Later I'll do a CP30 test on the trainer, set up power zones from that and see how they compare to the first method. I find it interesting that the difference in NP vs AHR is lower close to threshold than at lower efforts. I would have expected the opposite effect.

Gotta do something to keep the trainer workouts interesting, right? But I have discovered a new indoor toy for indoor rides: I downloaded the new Computrainer scenery pack. Now I can ride cyclocross trails through downtown Atlanta scenery. That's different.


Greg said...

Have you taken into effect the wind resistance?

Robert Jordan said...

It's obvious that the forces against the bike/rider are very different on the trainer and on the road. I'm just comparing a given power output to a given heartrate response for trainer vs. road efforts. Forces against the rider don't come into play directly in that comparison. The increased trainer HR response to a given power output probably is due to a combination of 1 - increased body temperature on the trainer; 2 - constrained position on the trainer; and 3 - lack of realistic momentum effects on the trainer.