dangle wrote:
Tom A. wrote:
I'm not buying the "split downtube" being a benefit...Me neither. It's been a long time, but didn't Damon Rinard say something about a FD tab causing more drag than an entire downtube? It doesn't seem like a split airfoil is really used anywhere else either.
That may be realistic. The Cd of a flat plate is 30X higher a good aerofoil. Does a downtube have more than 30X the frontal area of a FD tab? Probably somewhere around that number. So not exactly out of the realm of possibility on a first order approximation.
I think that it is more of a comment of how little drag the downtube generates, that the FD tab being a large amount of drag. The downtube gets a nice long airfoil since it is angled, so it is very low drag part of the bike.