The Shimano Dura-Ace RD-R9100 Rear Derailleur incorporates mountain-bike tech to enhance performance. Its design differs from the 9000-series, with the frame-mounting bolt no longer serving as the derailleur's pivot. This pivot has been repositioned rearward and downward, while the cable entry point has been optimized for better routing. These changes shield the derailleur from impacts and facilitate shifting across an 11-30 cassette. Shifting efficiency is improved, and the cable and housing are lighter and more rigid. The derailleur features a longer, carbon cage for weight reduction. The pulley pivot ensures consistent distance between the upper jockey wheel and cassette cogs, enhancing shift performance. The cage houses two eleven-tooth pulleys with deep cut-outs, reducing weight and preventing dirt accumulation. Compatible with 9000-series shifters, the Shimano Dura-Ace RD-9100 Rear Derailleur weighs 158g.