Two forces combine to slow down riders: air drag and inertia. DURA-ACE R9100 wheels are designed to combat these forces through aerodynamic features and reduced rolling resistance. Two new 28mm wide C60 and C40 rim platforms bring a stiffer wheel to enhance forward and side-to-side (lateral) power transfer and, with ultra-light carbon rim heights of 60mm and 40mm, are also designed to reduce air resistance. This allows Dura Ace R9170 C60 wheels, in a real world scenario, to save 16W over Shimano’s current DURA-ACE 9000 C50 wheelset. C24 wheels complete the DURA-ACE lineup giving riders three rim heights to choose from (60mm, 40mm and 24mm).