In late 2021 Shimano released their new Di2 12-Speed drivetrains, focusing predominantly on hydraulic disc braking moving forward, with wireless Di2 shift levers. The rim brake version did not get the wireless option, though the ports and wire set-up were updated for the 12-Speed generation battery, shift logic and functionality. Still, the levers did get other ergonomic and design features to also improve performance. Sold here as a set, the 12-Speed Shimano Dura-Ace Di2 ST-R9250 shift/brake levers for an SLR-EV rim brake system offer unparalleled wired shifting speed with customizable set-up, and incredible braking modulation and control. All these features are integrated into Dual Control shift/brake levers that are both lightweight and ergonomic thanks to the use of state-of-the-art materials ensuring optimum comfort and control even under challenging conditions. Dropping 65 grams from their Ultegra siblings, these levers feature a higher quality build overall in hardware and the use of CFRP to reduce weight and improve strength.

Shimano's Dura-Ace Di2 has long delivered the most precise, most reliable, and most efficient electronic shifting. With the 12-Speed generation rim brake combination, the ST-R9250 Di2 shifters can be wired from left to right, then to the battery if desired, or together via a simple junction box, then with a wire to the 3-port BT-DN300 internal seatpost battery using the thinner, lighter, new generation SD300 e-Tube wires. Only one cable can run to the battery, as the Front and Rear Derailleurs are each wired directly to the internal seatpost battery for greater overall battery power and time between charges. Overall the system is highly efficient, delivering about 1200 miles of use varying with shifting needs. The R9250 Rear Derailleur now integrates the junction, adjust/status control, and charging port, so a Junction A is not otherwise required.

Shimano has made refinements to the lever body and shift button design, providing the rider with a clearly defined click feeling, via a more ergonomic shift lever for quick and intuitive shifting. The updated hood shape and texture optimize grip and brake power transmission, while also ensuring better bike control and confidence in all conditions.