The worlds fastest Pulley Wheel system just got faster. OSPW Aero features a lifetime warranty and is wind-tunnel tested to have 40% less friction compared to a stock derailleur, making it perfect for time trials or triathlons. The OSPW Aero is an industry-leading product co-developed with one of the worlds leading aerodynamicists; Simon Smart and is chosen by World Champions and top performers around the world. This OSPW system has handbuilt CeramicSpeed Bearings installed and its unique design and craftsmanship will captivate you from the first time you use it. The system features a 13-tooth upper Pulley Wheel and a 19-tooth lower Pulley Wheel to provide absolute optimization of the rear derailleur and the upper and lower oversized aluminum Pulley Wheels come fitted with coated CeramicSpeed Bearings that have been perfected through years of experience.