tttiltheend wrote:
devashish_paul wrote:
I don't know how wedging a bike between your legs affects aerodynamics or if you can take the bike aero dynamics and the body aero dynamics and add up the theoretical drag, (I assume you cannot, because the presence of another object will affect what happens to the drag of a nearby object in a fluid)....but in any case, the speed skiers all go wide leg. I have tried wide stance and narrow stance on skis and wide is faster since the air can get around a narrower pipe (one leg) vs a fat pipe (2 legs) and reattach more easily. Its actually remarkable feeling the delta in speed on a steep downhill going wider
I'd be cautious about transferring skiing aerodynamics to cycling. A downhill racer goes for a wide stance since he can tuck his chest between the legs, plus it's more stable. He also doesn't have a bicycle between his legs. Whatever data I've ever heard about for cycling has indicated narrower legs are faster.
Which is why I prefaced it "not sure how wedging a bike between the legs affects things". But stability aside, legs apart on skis is faster than legs together.
Also related to wedging a bike between the legs, I believe early test on softrides and zipp 2001's with a rider on top showed them to be faster, and I believe this was less to do with the bike than the fact that there is a large gap between the two legs (no bike frame) allowing for better re-attachement around the legs. I would be interesting if TJ or someone from Dimond can comment on that aspect.
My personal downhill "windtunnel" on the bike, I have not had a single modern bike descend faster than my 1995 softride...by the way, the test hill (blacks lake hill in Gatineau Park in Ottawa) is the same one that I've used on skis. Sure, atmospheric conditions change, but when you go down the same hill a zillion times on every bike you own, you see some trends emerge.
But I would agree that when I press my knees together on the top tube of any bike, that is the fastest position on that bike while coasting, so with the bike in there between legs, I generally agree with "narrower is better" given that the bike fills the gap between the legs. But what if you could go with a really wide stance on a narrow width bike....maybe that is better aerodynamically than narrow if you can create enough space between bike and legs.
You can be certain if a speed skier could go faster narrower, they would figure out a way to ski that way and go fast (different than downhiller or GS skier). Look at the airfoil they attach to the back of their calves....if they could put feet together they would have a front semi teardrop fairing and a rear semi teadrop....but they create a full teardrop on each leg instead cause that's the fastest.