Example from a 2.4 mile / 3.9km segment with a lot of efforts as its a favorite route back towards town.
Two weeks ago I was in a tailwind with a small amount of drafting (~10 in peloton):
solving for that speed with an online calculator, I used -8mph effective tailwind:
close enough. (calculator: An interactive model-based calculator of cycling power vs. speed)
My young friend has the KOM at 30.4mph and 334W:
similar tailwind. So what does the calculator say if I tried to match that speed:
About 344W for me, which is a little more than what he put out on that KOM while pulling 2 guys. And I’m a little bigger, a little less aero.
So in a solo effort, with similar wind conditions, to go from 27.6mph to 30.4mph for nearly 5 minutes I would need roughly ~350W effort. Looking at my power curve:
makes me think it unlikely!!!
Back to your question…
- 30.4mph happens to be 10% faster than 27.6mph (a coincidence, I didn’t go looking for that)
- power increase required is 344/248 = 39% more power required
so in this example, a 10% speed increase requires about 39% more power, in a tailwind, in the real world on rough pavement and a steady ~12mph tailwind.
Here are two efforts on the 1 mile segment just before the segment above, separated by a week, one in the peloton and the other I got dropped just before the segment so its solo:
similar wind conditions.
Thats why the bigger guys (about my size) with 350W FTPs can hammer at 28+mph for 40-50 minutes on Tue/Wed/Thur worlds in this area. And why I get dropped with a 270W ftp.