Originally Posted by donrhummy
Hmmm, that's interesting. Everything I've read said that you gain about 20-30% from drafting (I've evejn seen 40%), but you're saying that is not the case.
But am i misunderstanding your numbers? Are you saying that if you ride at 13mph WHILE drafting, you'll get zero benefit? Or are you saying that if you normally average 13mph over a century that you'll get zero benefit when drafting and you'll still average 13 mph? If the second's the case, i think you need to be a bit more specific. Someone could average 13mph over a century, but at varying times during the ride they're cycling anywhere from 7mph-30mph depending on if they're going up/down hill or on flats. So they'd get benefit of drafting some of the time but not others.
Still, your estimates seem a tad low to me. The number of people doing sub 6hr centuries (solo) are VERY low, but the number who can do it with drafting are quite high.
Yeah, sorry, those were supposed to be instantaneous speeds, not averages. Technically there is probably some infinitessimal benefit to drafting at 13mph, but I would guess it to be less than 0.1mph. I don't know how accurate my numbers are, being that they're only from my experience.
Keep in mind that going 22mph takes more than 10% more than 20mph because air resistance is proportional to the square of your speed. Therefore drafting at 21mph, (using my numbers of 19mph effort, 2mph drafting bonus) you are using 22% less energy than riding solo at 21mph, which is consistent with the 20%-30% range.
Note that the faster you are going, the higher the energy savings from drafting will be. I estimate that at 13mph it is negligible savings, but there is certainly a speed at which you will derive a 40% energy savings for drafting vs solo.