tttiltheend wrote:
I'm not so sure about this. It seems more logical that rolling resistance is more important on the climb, where you're moving slowly and aerodynamics plays a much smaller role. I
Don't forget that the losses due to rolling resistance are proportional to speed. Not with the square of speed like in aero, but you're still going to get more losses descending than climbing. Way less overall time, of course.
And I just don't see that much of a difference in aero-ness between the two bikes. The the CX tires were 35mm vs. 25mm on the road bike. That's about it, other than small frame differences. But I was seeing a ~10MPH or more drop in speed while descending. It sure "felt" like rolling resistance losses to me. Was in super tuck, whole deal. Just could never get moving very fast, and the tires made a ton of racket, like driving snow tires on the freeway.
Of course, can't prove it.
Edit: Well I can prove it. Next time I wear out my CX tires I'll throw on some wide, fast tires, and see if I can descend fast.
Edit edit: Looking at the CX rolling resistances on BRR. My tires aren't on there, but I'm pretty sure they're slow. Kenda. If I pick 30W/tire @ 18MPH, that becomes ~60W/tire at 36MPH (about as fast as I could go on descents where I can normally hit 50MPH super-tucked). Or 120W of losses. Easily enough to get dropped on a descent. I'll throw in maybe 50W more of aero losses due to tire width and a little bit for wheels that are slightly less aero than the training wheels on my road bike. That's my hand-waving guess.
But nevertheless, my point about Everesting should still hold: fast tires will matter on descents.