What are the benefits of the underslung rear brake?

We knew this placement was ideal from our 2006 aero studies. First, it saves 40g of drag. The chainstays are also a more suitable structure on which to mount the brake; they are made to take a huge load from pedalling forces. The seatstays have less stress and much of their load comes from braking. By moving the brake we can remove the seatstay bridge and make the seatstays more compliant, aiding our goal of improving the ride quality. The new brake location is also in line with the axis of rear wheel deflection under high pedalling forces, helping to make brake rub even less of an issue.