SRAM Hydraulic Discs and Calliper Brakes

by CyclingTips

Hydraulic disc and calliper brakes revolutionised mountain biking over a decade ago and it’s been long rumoured that they’d be making their way onto production road bikes. Well it appears that SRAM may not be too far off. Over the weekend there were a couple bikes with some subtle but interesting parts riding around Melbourne and I managed to get some photos…


It’s easy to see the advantage of hydraulic disc and calliper brakes in wet and muddy conditions. Braking is better and there’s less rim and brake-pad wear. Perfect for mountain bike and cyclocross. But even in dry conditions the braking modulation is better and more reliable on discs. It also means that rim heat dissipation on the rim is no longer a problem (something that is an issue with carbon clinchers). With disc brakes you can have all the benefits of a carbon clincher, but with a lighter rim, better and more predictable stopping power, and possibly even better aerodynamics. Also, when a wheel comes seriously out of true, braking isn’t affected when you’re running disc brakes.

Hydraulic actuated calliper brakes have the benefit of an overall lighter system and more cable routing options. Also, since the front and rear brakes have a much different cable length between them which requires different amounts of force to pull each with unpredictable stopping power. A hydraulic system requires the same amount of braking force to be applied at the levers which results in better modulation.


The bike that I photographed the disc brakes on was a Cannondale SuperX, a cyclocross bike that had disc mounts on the frame. There’s no easy way that disc brakes will be fitted onto a standard road frame/fork the way they’re currently designed. The fork and rear stay need mounts for the braking mechanisms, and they most likely need to be strengthened to withstand the extra braking load.

Wheels also need to be modified. The hub needs to be able to accomodate a disc and I’m not totally certain, but a different lacing pattern may be required.


UCI technical regulations state that disc brakes are not allowed in road races. However, Velonews indicated that UCI technical coordinator Julien Carron said that this will be re-evaluated in 2013. Carron told Velonews, “The UCI is not necessarily against its use, but we need more time to make the correct decision regarding the safety in competition. I cannot give you a precise timeline, but this will be an important topic of the next equipment commission this summer. We are currently studying the possibility to open its use in competition, but we would not like to worsen the situation by increasing the difference of braking behavior inside the peloton.”

Road racing is steeped in tradition and I think it’s safe to say that roadies are not early adopters of new bike technology. Mountain bikers are triathletes are the exact opposite. Personally, I’m a big supporter of innovation which is what eventually leads to progress. Just like Di2 or the iPad, they didn’t appear to be filling a real need. But once you use either of them, you’ll never turn back.

Are hydraulic disc or calliper brakes the next big advancement in road bike technology? Or is this solving a problem that just didn’t need to be solved?

The hood shape his slightly higher (approx 15mm) to the regular Red lever to accomodate the hydraulic master cylinder.

The rotor size we see here is 140mm (rear)/160mm (front), which is the same as most current cross country brakes. Anything smaller negates some of the benefits of going to discs, so we probably won't see them get any smaller than 140. There is one piston on the levers, and two pistons on each of the brake mounts.
Colnago came out with a disc brake C59 a few months back. From what I understand, the reason they're able to get the levers nice and compact is because they're using Di2 which does not contain any shifting mechanicals inside the hoods (just an electronic button). When will we see electronic shifting from SRAM? We'll wait and see...

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