The Cervelo S2 is the original carbon aero road frame. It's the workhorse of Cervelo team riders because of it's stiffness, comfort, and sheer speed. With Cervelo's True Aero tube shapes on the entire front triangle, the S2 offers wind cheating advantages at the speeds cyclists commonly ride. Made of unidirectional carbon fiber, Cervelo engineers are able to put the right amounts of material where it's needed. The Bottom Bracket area is massive while other areas have minimal material, giving the bike excellent acceleration and light weight. Once up to speed, the S2 holds it easily thanks to the aforementioned aerodynamics.