This is system engineering at its peak. The Dura-Ace range offers an unparalleled level of performance and is all about optimising input to maximise output. That's how it achieves supremacy. Utilising the Shadow design technology, the Dura-Ace R9100 rear derailleur offers a sleek appearance and optimised and consistent shifting performance. The low-profile shadow design places it closer inbound to the frame and tucks the derailleur under the cassette. This helps to protect the derailleur in the event of a crash and minimises the general risk of being bumped and banged, allowing it to remain better aligned for smooth, quick and consistently accurate shifting performance. The SS version allows for a wide gearing range and accommodates up to a 30t rear cassette.