Shimano Dura-Ace Di2 R9250 12-Speed Rear Derailleur

Shimano Dura-Ace Di2 R9250 12-Speed Rear Derailleur The Shimano Dura-Ace Di2 R9250 Rear Derailleur acts as the brain for the 12-speed semi-wireless gear set-up. It houses the wireless hardware that communicates with the shift levers but is also hard wired to the front derailleur and the battery, acting as the master link for the whole system. Additionally, it’s also the system’s charging point, provides ANT+ connection to third party devices, features the button responsible for all Di2 operations and integrates an LED light that provides information on shift modes and battery charge levels. It works within several shift settings that are fully programmable via the Di2 app, granting personalised and intuitive shifting behaviour. From a mechanical standpoint, a longer cage length means that compatibility with 11-28 through to 11-34 ratio cassettes is fully supported. The cage is made from carbon to increase rigidity and lower weight, while the cold-forged aluminium link plates of the derailleur body are strong to donate snappy gear changes and highly resistant to corrosion. The overall profile is realised via Shimano's Shadow concept to create a minimal silhouette, and a "fuse" function automatically activates during a crash to protect it from damage. DuPont Zytel pulleys complete the design, guaranteeing durability and damping drivetrain noise.