Power, Meet Surge The DURA-ACE Rear Disc Wheel minimizes drag in time trials and triathlons, helping maintain speed over long distances. A full disc construction and highly optimized aerodynamic profile work together to maximize efficiency when every watt matters. Features Full Disc Wheel Design: Full disc construction reduces aerodynamic drag and improves efficiency during sustained high-speed efforts Aerodynamically Optimized: Refined through extensive aerodynamic development to minimize resistance and support higher average speeds Time Trial and Triathlon Specific: Purpose-built for racing disciplines where aerodynamic efficiency has the greatest impact on performance Engineered for Long Efforts: Designed to maintain speed and efficiency over extended distances, helping riders execute pacing strategies effectively Direct Engagement Freehub: High-stiffness freehub construction delivers efficient power transfer during acceleration and at race pace Includes tubeless valves, packaged separately and ready for installation Erase the Air The full disc construction is engineered to minimize aerodynamic drag and maximize efficiency at speed. Designed for time trials and triathlons, it helps riders maintain momentum and conserve energy over long race efforts. Optimized as a System When paired with the DURA-ACE C99 front wheel, the Rear Disc completes SHIMANO's most aerodynamic wheel system. Together, they deliver the efficiency and speed retention needed for time trials and triathlon racing.