Purpose-built for gravel and mixed-terrain riding, the Shimano GRX BL-RX610 left-hand brake lever and BR-RX400 rear hydraulic disc brake caliper deliver consistent, powerful braking in demanding conditions. Designed for 1x drivetrain setups, this brakeset pairs a tactile, ergonomic lever with a proven two-piston flat mount caliper — all pre-bled and ready to install via Shimano's J-Kit system.

Highlights

• GRX BL-RX610-L left-hand hydraulic brake lever — rear brake control (Australian configuration)
• BR-RX400 two-piston flat mount hydraulic disc brake caliper
• J-Kit pre-bled from the factory — no bleeding required on installation
• Reach Adjust for a personalised lever feel regardless of hand size
• ICE Technologies heat dissipation for fade-free braking on long descents
• 1700mm SM-BH90 hose — correct length for rear routing

Lever Design

The BL-RX610-L is a dedicated hydraulic brake lever — not a combined shifter — making it the ideal choice for 1x gravel builds where a separate dropper post remote or thumbshifter occupies the bar. The textured hood and anti-slip lever surface maintain confident grip in muddy or wet gravel conditions, while the Reach Adjust mechanism lets you dial the lever to your preferred distance from the bar without tools.

BR-RX400 Caliper

The BR-RX400 is a two-piston flat mount hydraulic caliper drawn from Shimano's GRX gravel groupset. ICE Technologies pads and caliper design work together to dissipate heat efficiently, keeping braking feel consistent even on long Alpine descents or when loaded with bikepacking gear. The One Way Bleeding system simplifies future maintenance, making it easy to purge air quickly and get back on the trail.

Compatibility & Fit

Compatible with flat mount disc frames (road and gravel geometry). Works with Shimano GRX-compatible rotors including the SM-RT70 and SM-RT64 — rotor is sold separately. Designed for 1x12-speed GRX drivetrains. Uses Shimano mineral oil (not DOT fluid). In Australia, the left-hand lever controls the rear brake.