Techs & Features: Advanced SL Composite Technology Professional Grade raw carbon fiber is woven in our composite factory to produce our lightest, stiffest, and highest-quality frames. This is the technology used by Giant's pro racers in almost every cycling discipline. OverDrive Giant's original oversized fork steerer tube technology. Designed to provide precise front-end steering performance, the system's oversized headset bearings (1 1/4" lower and 1 1/8" upper for road, 1 1/2" lower and 1 1/8" upper for mountain) and tapered steerer tube work in conjunction to provide optimal steering stiffness.