i thoroughly enjoy http://www.bicyclesports.com/technical/index.html

the aero stuff on there is written by the guy who works w/ lance. it's almost information overload, but i'm kind of a science geek so i enjoy that sort of stuff. also, realize the guy's a tri/aero freak, so most of the stuff is towards shaving .1 sec off a time trial, not comfort. but it's still good material.