Time trial and triathlon bikes lived with mechanical brake calipers longer than any other road category, mostly because nobody had built a hydraulic lever that fit an aero bar clamp. SRAM's S-900 Aero HRD solved that with a purpose-built TT lever paired to a flat mount caliper, sold as a complete front or rear unit with a pre-bled hose and Stealth-a-majig connector for setup. SRAM made a big leap in improving the braking capabilities of TT and tri bikes with the release of the HRD disc system, as the new brakes are fully hydraulic — the first of its kind to be released by one of the big component brands. The S-900 HRD brakes are not integrated with eTap shifting and are brake-only , so if you're building a TT bike around SRAM eTap AXS shifters up top, this handles the stopping side independently.

The lever body is carbon LFRT (long fibre reinforced thermoplastic) with a textured finish so your fingertips don't slide off in wet or sweaty conditions, and reach adjust lets you dial the blade closer for smaller hands or farther out for gloved winter riding. It mounts to the end of a clip-on extension or the end of a base bar via a draw bolt clamp — one lever per side, and the front and rear units come with different hose lengths matched to the run each brake needs.

The caliper is flat mount only, with 0 or 20mm offset , and SRAM recommends either a 160mm or 140mm rotor for TT and tri use . Rotors and mounting hardware are sold separately, so plan on adding CenterLine or CenterLine X rotors to your order if you don't already have them. Fluid is DOT 5.1 , the same as the rest of SRAM's road hydraulic line, which means shared bleed kits and fluid across your service bench.... Read More