The brand new, futuristic Shimano Dura-Ace 9100 Rear Derailleur has been completely redesigned to match the new shift performance of the R9100 mechanical road group. This 11-speed derailleur takes on several features previously seen on Shimano M9000 XTR group, including the “Shadow” low-profile design. A significant improvement to the new derailleur is its ability to run a 30T cog, something the previous generation couldn’t. Because of the extra range, Shimano is offering just the single cage length.
Shimano Dura-Ace R9100 Rear Derailleur