The Shimano Dura-Ace BR-R9170 is the rear hydraulic disc brake calliper at the pinnacle of Shimano's road groupset lineup. Designed for elite road racing, it delivers precisely modulated stopping power with the confidence and control that demands of the world's fastest courses — paired here with the L02A resin pad for smooth, consistent performance across a wide range of conditions.

Highlights

• Flat mount design: Low-profile, integrated mounting system keeps weight down and suits modern road disc framesets without the need for an adaptor.
• One-way bleeding system: Shimano's streamlined oil route eliminates trapped air bubbles and makes the bleeding process fast, clean, and straightforward.
• Two-piston hydraulic caliper: Refined twin-piston design delivers an optimal balance of power and modulation, with pistons that self-adjust and retreat further for generous rotor clearance.
• Wide pad clearance: Chamfered pad edges guide the rotor in cleanly, reducing rub and simplifying wheel installation.
• Mineral oil hydraulic fluid: Non-corrosive mineral oil system is safer to handle and kinder to painted surfaces than DOT fluid alternatives.
• Race-ready performance: Engineered for Dura-Ace Di2 and mechanical disc brake systems, giving World Tour-level braking to any road disc build.

Engineering for Road Racing

The BR-R9170 sits at the heart of Shimano's R9100 Dura-Ace disc platform. Every detail has been refined for road racing: the compact, aerodynamic calliper profile reduces drag, while the hydraulic circuit has been optimised to deliver consistent feel from the first touch of the lever to full braking force. The two-piston design balances braking power with the fine modulation road racers rely on when cornering at speed or managing descents.

Simple Setup and Maintenance

Shimano's one-way bleeding system uses a funnel tool and mineral oil, keeping the process clean and minimising the chance of air re-entering the system. Wide pad clearance and chamfered pads make wheel swaps fast in race conditions — no fiddling required.

Compatibility and Fit

Flat mount calliper — fits frames and forks with a flat mount disc brake interface (no adaptor required for standard flat mount). Compatible with Shimano Dura-Ace R9100 series hydraulic disc brake levers including ST-R9170 (Di2) and ST-R9120 (mechanical). Uses Shimano mineral oil. Supplied with L02A resin pads (with fin). Compatible with Shimano SM-RT900 rotors in 140mm and 160mm sizes (sold separately). Fixing bolt for 25mm mount thickness included.