It's not so much the weight but aerodynamics. The top aerobikes (not timetrial bikes) use about 10-20% less power than a non aerobikes at a speed of 45km/h (whi

It's not so much the weight but aerodynamics. The top aerobikes (not timetrial bikes) use about 10-20% less power than a non aerobikes at a speed of 45km/h (which is not a high speed during racing). That has actually been the big innovation in the last 5 years, the realisation that aero is more important than weight, except for the most extreme mountain stages. All the big manufacturers are now making aerodynamically optimized bikes.