I'm going to take the bike in to the bike shop before RAGBRAI this summer, so I'll try on some different helmets for fit there. Considering that there is a lot of variation in fit from one kind to another, I don't think I can just order one form Performance Bike or something. About that impact question, I really don't think that the helmet took any major blows. The shell is just a little chipped in a few places, but it's enough to bug me. Also, I think that newer helmets have more and bigger vents, and are probably cooler as a result.