Originally Posted by Doge

Matters a lot. How much? San Dimas uphill TT 1lb means about 10sec for a relatively fast 140 rider on a 15# bike vs. a 16# bike.
Its not going to make much difference in a pack, but uphill alone - weight matters. Aero matters too - flats and alone. Flats in a group aero matters less. We have both (Tarmac, Venge) and have put the bucks into the aero to get it light. If you win on sprints - different deal.