Hope

RX4+ SL Rear +20mm Flat Mount SRAM Disc Brake

The Hope RX4+ SL Rear +20mm Flat Mount SRAM Disc Brake Caliper is a slimline, 4-piston DOT-fluid caliper designed to bring more control, consistency, and outright braking torque to SRAM road and gravel hydraulic systems. Its CNC-machined monobloc construction targets a firmer lever feel and reduced pad rub, while recent RX4+ SL updates focus on better frame compatibility and easier workshop service without compromising the precise modulation Hope calipers are known for.

Key reasons riders upgrade to a 4-piston rear caliper

1. Narrower Bore Cap Profile - Reduces overall caliper width for improved clearance on tight flat-mount frame and fork designs (updated with the narrower style introduced on Hope GR4/TR4).
2. Monobloc CNC Construction - One-piece, precision-machined caliper body increases stiffness for a cleaner, more direct lever feel and more stable pad alignment under load.
3. 4-Piston Power with Better Modulation - Extra piston area supports stronger braking and better heat management than typical 2-piston road calipers, especially on long descents or with heavier riders and bikes.
4. RX2-Style Bleed Nipple - Updated bleed port design is intended to make bleeding simpler and cleaner during routine service.
5. 2014-T6 Aluminum Body - High-strength alloy supports durability while keeping weight in check for performance-focused builds.
6. Service-Friendly Details - Fully serviceable design and top-entry pad access speed pad changes and extend service life; compatible with 140/160/180mm rotors with the appropriate flat-mount setup/adapters.