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Sram launches S-900 Aero HRD disc brake system

The new brakes are specifically for time trial and triathlon use, are fully hydraulic but don't yet have shifting capabilities

SRAM have 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. This is the first of its kind to be released by one of the big component brands.   

The S-900 HRD disc brakes are not yet integrated with eTap shifting and are brake-only, but are said to offer "optimised power and modulation for time trial and triathlon". The claimed weight is 240g, and the levers are made out of a textured carbon, offering better feel and control than regular TT levers. They also have different levels of reach adjustment for various hand and finger sizes.  
The calipers themselves are flat mount only, and SRAM recommend either a 160mm or 140mm rotor for TT and tri use. Sram's Bleeding Edge technology means that the faff is taken out of brake bleeding, and they say it's possible for a home mechanic to perform a bleed in 90 seconds flat. 


sram brake on bike.jpg

The brake system is seen here on a Cannondale Super Slice

As the first wave of disc-equipped TT bikes reached the market last year, including the radical Cervélo P5X, the technology wasn't ready for the bikes to come with full hydraulic disc brakes, so the P5X, Parlee's TTiR and Diamondback's Andean to name the three that caught the most attention were built with half-and-half set-ups. Though Cervélo told us at the P5X's European launch that mechanical was advantageous because they don't require bleeding, Sram's Bleeding Edge system negates this advantage and means full hydraulic is now a no-brainer - you can only hope those that forked out up to £13,500 for the first batch of P5X's get a complimentary upgrade to hydraulic, something Cervélo told us they would endeavour to offer when the technology becomes available. 

The new hydraulic disc brake revolution debuted at the Tour de France prologue, with Cannondale's new Super Slice speccing the S900 HRD system. It will be available from September, with the brakes priced at £235 and the rotor £63.  



Arriving at in 2017 via 220 Triathlon Magazine, Jack dipped his toe in most jobs on the site and over at eBikeTips before being named the new editor of in 2020, much to his surprise. His cycling life began during his students days, when he cobbled together a few hundred quid off the back of a hard winter selling hats (long story) and bought his first road bike - a Trek 1.1 that was quickly relegated to winter steed, before it was sadly pinched a few years later. Creatively replacing it with a Trek 1.2, Jack mostly rides this bike around local cycle paths nowadays, but when he wants to get the racer out and be competitive his preferred events are time trials, sportives, triathlons and pogo sticking - the latter being another long story.  

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RobD | 7 years ago

I assume these would work with their hydraulic rim brakes as well, or have they disappeared off the radar? seems like that would potentially be useful on TT bikes where cable routing can be a bit tricky and they're not known for their braking performance.

Yorky-M | 7 years ago

think somepone was overkeen photoshopping the top of the cockpit

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