Light & strong these S-Works carbon road arms & spider give you the competitive advantage. Light & strong these S-Works carbon road arms give you the competitive advantage. Hollow carbon crank arms offer superior stiffness. Oversized alloy spindle with Hirth coupling interface. Fits Specialized road frames with OSBB or PF30 bottom bracket shell.BB30 compatible. Compatible with Shimano & SRAM drivetrains. Finish: Unidirectional carbon fiber Spider: 110BCD