34 vs 38- any actual data?
I hear alot that to get tangible aerodynamic benefits from a wheel the rim must be at least 38 mm deep. This assumption has led some people to argue that an "aero" rim 34 mm deep would be all but worthless. Is this really true? Does anyone have any actual data to back this claim up? From what I've read, the 38 mm figure comes from the Zipp website- not too reliable in my eyes since theyre clearly trying to sell their own wheels. Could you point me in the right direction to find out more about this?
Saw a wind tunnel test a couple of years ago...
I saw a report on a wind tunnel test a couple of years ago that supported the 38mm claim, but it isn't going to do you much good, because I can't remember where and I think it might have been the same one they refer to on the website.
As a practical matter, though, how much difference could there be between 34 and 38? It may exist, and if it does it probably can be measured, but that extra 4mm isn't going to make you get on the bike and say, "Wow, feel THAT!"
The difference between zero and nada
Quote:
Originally Posted by weiwentg
I do not remember where I got this info, but I have heard also that a v-section rims (e.g. Velocity Aerohead, Ritchey WCS/Pro, Campy Shamal) are better than box section (Open Pro, Campy Neutron, etc). the v section reduces the turbulence created over a box section or something.
Like most of the advertising in cycling, it is misleading. It isn't just the chord to thickness ratio, but the profile. The profile of every rim I've seen less than the Zip/Reynold's 58mm carbon rim looks nasty. I'd like a rim that with an inflated tubular on it that closely matches the NACA 2412 airfoil profile.