There is a lot of prejudice against 650c wheels here and on other forums and sites, and frankly, I am getting so weary of it. I used to have a 650c carbon Aegis Swift, and I could keep up with or beat nearly every woman in our bike club -- and good number of the men as well! Remember what Lance said: "It's not about the bike"??? The bike does matter, but even more important is the engine. My bike was light and I was in fabulous shape (this was before my accident in 2005 where I fractured my pelvis in three places -- I'm not as fast now).

If I were to build a new go-fast bike today, I wouldn't hesitate to use 650c wheels again as they lend themselves to a bike geometry that fits me, and since they're smaller, they are lighter and accelerate faster! You give up a bit in easy rolling, but the difference is balanced out by the weight and acceleration advantage.

I did have a 700c bike earlier in my cycling career but it was just too big for me. With today's sloping top tubes and compact geometry (which, admittedly, I've never tried), I could probably fit a 700c wheel and would consider it, but I would never rule out 650c wheels on principle.