Cervélo pioneered the Extended Seat Tube Cutout. The seat tube has a close-fitting curve in the seat tube that shields the leading edge and top of the rear wheel. The rear wheel is effectively hidden from the wind, significantly reducing aerodynamic drag.
In order for the Extended Seat Tube Cutout to be effective, the tire must fit closely to the frame and the seat tube cross section must have the right shape to help air flow smoothly across the seat tube and around the wheel. We incorporate this knowledge into every Cervélo model with an Extended Seat Tube Cutout (see below).