The Shimano Ultegra ST-R8170 brings the semi-wireless Di2 shifting and SERVO WAVE hydraulic braking of the Ultegra R8100 groupset into a single, ergonomic left-hand lever — delivering precision front shifting and confident brake modulation for road cyclists who demand performance without the Dura-Ace price tag.

Highlights

• Semi-wireless Di2 electronic shifting with 12-speed front derailleur control
• SERVO WAVE hydraulic actuation for rapid pad engagement and smooth, progressive braking
• Reach and free-stroke adjustment for a personalised fit to any hand size
• CR1632 coin-cell battery — user-replaceable, up to 1.5–2 years typical life
• One SD300 port for satellite shifters (drops, bar-top, or TT extensions)
• Customisable shift modes via Shimano E-Tube Project app (Synchro-Shift, Semi-Synchro-Shift, manual)
• Ergonomic hood profile engineered with professional rider input
• Mineral oil hydraulic system — consistent brake feel as pads wear

Semi-Wireless Di2 Shifting

The ST-R8170 uses Shimano's second-generation semi-wireless Di2 architecture. The lever transmits shift signals wirelessly to the rear derailleur while a lightweight EW-SD300 wire can connect satellite shifters for additional control positions. Shift modes, button assignments, and Synchro-Shift behaviour are all configurable via the E-Tube Project smartphone app — no specialist tools required.

SERVO WAVE Braking

Shimano's SERVO WAVE technology varies the mechanical leverage ratio across the lever stroke, delivering rapid initial pad-to-rotor contact followed by a controlled, progressive squeeze. The result is precise brake dosing whether you're descending at speed or navigating technical corners. The hydraulic system self-adjusts for pad wear, so the lever feel remains consistent throughout the pad's life.

Ergonomics & Adjustment

The redesigned hood raises and reshapes the grip area for a more secure hold in all riding positions — on the hoods, in the drops, and on the tops. Reach adjustment allows you to bring the lever blade closer to the bar to suit smaller hands, and free-stroke adjustment fine-tunes the point at which the pads engage. The lever weighs approximately 195 g.

Compatibility & Fit

The ST-R8170 left lever is compatible with flat-mount hydraulic disc brake calipers BR-R8170 and BR-R9270, front derailleurs FD-R8150 and FD-R9250, and Shimano brake hoses SM-BH90-J-SSR / SM-BH90-JK-SSR. It works with SW-RS801 satellite shifters and accepts optional sub-brake lever BL-RX812. The lever clamps to standard drop bars (23.8–24.2 mm clamp diameter) and uses Shimano Mineral Oil. This is the left lever only — pairs with the ST-R8170 right lever (sold separately).