The Shimano Ultegra ST-R8170-L brings wireless Di2 electronic shifting and precise hydraulic disc braking together in a single left-hand lever — giving you full front-brake and front-derailleur control with cleaner cables, smarter ergonomics, and Shimano's proven Servo Wave modulation.

Highlights

• Wireless Di2 electronic shifting — no shift cable required between lever and derailleur
• Servo Wave hydraulic disc brake technology for progressive, intuitive modulation
• 2x12-speed compatible — controls front derailleur (FD-R9250 / FD-R8150)
• Carbon fibre reinforced polymer (CFRP) hood body for lightweight rigidity
• CR1632 coin-cell battery with 1.5–2 year estimated lifespan
• 16.4 mm reach adjustment range to suit different hand sizes
• Three programmable multi-function switches per lever via E-Tube Project app
• Hood body positioned 4.6 mm longer than the previous R8070 generation for improved grip
• Compatible with satellite shifters (SW-RS801, SW-RS802) for aero or TT bar setups
• Shimano mineral oil hydraulic system — compatible with BR-R9270 and BR-R8170 calipers

Wireless Di2 Platform

The ST-R8170 forms part of Shimano's all-new 12-speed Di2 wireless platform, shared with Dura-Ace R9200. Shifting signals are transmitted wirelessly via Bluetooth Low Energy to the rear derailleur (master unit), which then forwards commands to the front derailleur — eliminating shift wiring from the handlebars entirely. Battery replacement takes under a minute and the lever integrates with the Shimano E-Tube Project app for custom button mapping, Synchro Shift, and Semi-Synchro modes.

Servo Wave Hydraulic Braking

Servo Wave technology varies the mechanical leverage ratio across the lever stroke: initial movement sweeps the pads quickly to the rotor with light finger force, then transitions to greater mechanical advantage as braking load increases. The result is confident, fatigue-free modulation on long descents. Reach can be adjusted across 16.4 mm without tools to dial in your preferred lever position.

Ergonomics & Construction

Developed with feedback from professional road riders, the R8170 hood features a raised peak for secure grip in the drops and a longer body profile compared to the previous generation. The lever blade is aluminium; the hood body is CFRP for a balance of stiffness and weight. Longer shift paddles with increased spacing make tactile identification easier, even in gloves.

Compatibility & Fit

This is the left-hand lever, controlling the front brake and front derailleur on a 2x12-speed road drivetrain. Compatible derailleurs: FD-R9250, FD-R8150. Compatible calipers: BR-R9270, BR-R8170. Recommended hose kits: SM-BH90-J-SSR or SM-BH90-JK-SSR (sold separately). Uses Shimano mineral oil. Designed for standard 31.8 mm drop bar clamp. Sold as a single lever — pair with the ST-R8170-R right lever to complete the set.