Of course Johnson’s slant is decidedly ’cross focused, where the impact of things like added weight and reduced aerodynamics are less profound. We don’t have full weights of the new SRAM system, but it’s reasonable to expect that swapping on disc brakes could add anywhere from 200 to 500 grams of heft to your rig. This number remains in flux in part because the industry is still trying to nail down what size disc rotors will work for the various applications, be them ’cross, gravel road riding, or going full monty, and dive bombing steep paved mountain roads at 55mph.
This is ample ammunition for some disc detractors, who remain unconvinced that change is for the good. “I think when people discover how much heavier [disc brake systems] are, and how much they detract from the aesthetic of what we have come to envision as the ideal form of a road bike, that is going to be tough for a lot of people,” said Mavic PR man Zack Vestal, alluding to the fact that a pair of 160mm rotors can easily weigh 160 grams. “I honestly think it is going to be more niche for more years than everybody is willing to admit at this point.”
Out of the gate, SRAM is recommending 160mm rotors for paved use and 140mm for off road. But others within the industry see those numbers as a still-moving target.
“Of course like everyone else, we are looking at disc and seeing where we should go with it,” said Cervélo founder and chairman Phil White. “The feedback so far is that you can’t do 140mm disc rotors, it has to be 160mm or maybe even 180mm. And that becomes a challenge for aerodynamics and weight. But certainly we are looking at road disc, we just but don’t have an informed position yet.”
It should be noted that White – and just about anyone who builds time trial bikes — is a fan of hydraulic rim brakes. Cervélo’s recently released its revamped P3 time trial bike, which is spec’d with Magura’s RT6 hydraulic rim brakes. The advantage, of course, is that hydraulic systems don’t encounter the same routing issues as cable-actuated brakes when it comes to navigating the circuitous shapes of TT bike frames. They also typically have a more aero shape, tucking inside the borders of frame tubing better than their cable-actuated cousins.
“Obviously disc brakes require some special modifications to frames, but hydraulic rim brakes can be mounted to anything,” said Charles Becker, SRAM’s category manger for road and triathlon. “With Hydro Rim Road you get a ton of the benefits that come with hydraulic braking even though it’s still a pad on a rim. The amount of hand effort required is much less, and you are totally freed from cable routing issues because hydraulic hoses don’t care what shape they are in. So a lot of these aero bikes with the very challenging routing issues can now easily be overcome, whereas a bad angle with a cable system can really effect the performance of the brake.”
Becker’s first statement, that disc brakes require some frame modifications, leads one to wonder how deeply the industry has already committed to this new technology. You would assume that the SRAM brain trust wouldn’t release new technology into a marketplace that’s not ready to accept it. And indeed, it appears that’s the case.
“We have been working with several bike manufacturers for two-plus years on this project,” SRAM’s Becker confirmed. “There are already many bikes that are ready [for disc brakes]. The bikes you see here [at the SRAM Red 22 launch at Sea Otter] are production Specialized Roubaix bikes. And of course cyclocross disc frames have been around for a while now. Most are mechanical, but they can certainly be converted to hydraulic.”