Light and strong these s works carbon mountain arms give you the competitive advantage best strength to weight ratio on the market third generation hollow carbon crank arms offer superior stiffness oversized alloy spindle with hirth coupling interface 42mm bb30 cartridge bearings fits specialized frames with 845 osbb all frames with 73 bb30pf30 s works chainrings and spiders available separately in triple and double configurations available lengths 170 175 180