The shimano rs81 c50 is a high performance road racing wheel that meets the demands of todays professional and amateur riders this carbon and alloy clincher rim is both lightweight and rigid whilst maintaining high braking performance with standard brake pads key features 224 mm wide d2 carbon rim with alloy braking surface for improved aerodynamics and increased rigidity for sprinters and tt specialists 21 rear and 16 front stainless steel butted and bladed straight pull spokes for