Why? Weight only matters (a little) when climbing, when accelerating, and when you're lifting the bike into your car at the end of a ride. On the flats and down hills, aero trumps weight. Me and my 30 pound Gold Rush are minutes faster on the flats than equivalent riders on 20 pound uprights, and I can ride their wheels off down slope. Going back up I go at about the same speed as them, but then I'm 6-foot-4... not the classic "climber".