Two bolts, in this case, are better than one.
Do not be fooled by the nasty, ill-tempered, poorly functioning U-brakes of mountain bikes past. The latest direct-mount road brakes may look somewhat similar, but they exist in an entirely different realm of fit and function.
Shimano’s Dura-Ace BR-9010 Direct Mount brakes, which mount via two bolts instead of just one, are the best rim brakes the company has ever produced; perhaps the best rim brakes ever. They are lighter, stiffer, and more powerful, with better lever feel and finely tuned, utterly predictable modulation. As icing on that already delicious brake cake, they improve tire clearance substantially, are dead-easy to set up, and can never be knocked out of place.
At its core, a good brake is fixated on the perfect balance between power and modulation. But the tangential benefits of a particular design — tire clearance and ease of setup and maintenance — should not be ignored. It’s in these areas that a new design, the first big change in rim brake design in decades, steals the show.
Direct-mount is so good that leaving it to time trial and aero bikes is simply a waste, and a shame. Look for the design to make its way onto a growing list of standard road frames in the next few years.
I’ve spent the summer on Shimano’s 9010 option and am convinced it’s the rim brake of the future. Why? Read on.
What is direct-mount?
When the new brakes first cropped up aboard Trek’s redesigned, aerodynamic Madone frame in 2012, the sleek, semi-integrated design appeared to be aimed squarely at reducing aerodynamic drag. But as they’ve made their way onto other frames — including the not-at-all aerodynamic Trek Emonda — it’s become clear that the design is about much more than sleek, drag-reducing integration.
By mounting the pivots directly to the frame, excess material in both frame and brake can be eliminated, reducing weight. Bontrager’s version drops about 80 grams relative to a pair of standard Dura-Ace calipers.
The entire brake sits much closer to the frame, and the whole setup is significantly stiffer. That improves both power and modulation by removing flex from the system.
Each arm is adjustable, and the brake can never twist out of alignment once set up. It can’t twist at all, actually. That’s bad news for pros seeking “brake adjustments” (pushes from the mechanic in a car) after a mechanical, but great news for the rest of us.
Shimano’s 9010 direct-mount brake can be easily dialed in or out for different rim widths; we had no trouble swapping from a narrow aluminum set to Zipp’s ultra-wide 303 Firecrest carbon clinchers. You get the same tool-free adjustments as on any other Shimano brake: a quick release tab and a micro-adjust barrel.
The design dramatically improves tire clearance as well, as the brake sits higher on the frame or fork. Though safety standards prevent both brake and frame manufacturers from recommending anything over a 27 or 28mm tire, we’ve easily fit 30mm clinchers (on wide rims, no less) into the Emonda with direct-mount Dura-Ace brakes. Bontrager’s new version of the brake offers still more room — Trek employees have run up to 31mm tires in the Emonda with those brakes. The limiter is the space provided by the frame itself, not the brake.
In today’s world of voluminous road tires, that’s a big deal. One of the primary arguments for the move to disc brakes is increased tire clearance; being able to run 28 or 30mm road tires with room to spare eradicates that argument.
Theoretically, direct-mount should improve aerodynamics as well, as the brakes sit closely tucked into the frame and fork. But we’ve yet to see any hard proof of drag reduction.
Direct-mount brakes are being adopted quickly by the world’s top-end frame manufacturers, from Trek to Fuji to Lapierre, and more brands are lining up to adopt the new standard.
Currently, the only direct-mount brakes available are from Shimano, FSA, and Bontrager, but the standard is open. There’s no reason why SRAM, Campagnolo, and other brake manufacturers couldn’t jump on it (and they should.)
Even roses have a few thorns
All is not peachy in direct-mount land. There are two very small hangups with the design.
Shimano’s direct-mount brakes are a bit trickier to mount. The two sides separate quite easily. Each must be mounted in order, and must be connected via a small spring. These changes upgrade installation difficulty from “monkey” to “puzzle-solving chimpanzee.” It’s still dead easy.
Second, and this is truly picking the smallest of nits, the design requires that the small bolt or pin that holds the brake pads into their holders be moved from the rear-ward end of the holder to the front. There simply isn’t clearance to leave it where it has resided on most other brakes for years, because the brake sits so much closer to the frame.
As a result, many old brake pads will not work with the new brakes. The backside of most pads has a small gap, space for that aforementioned bolt or pin to slot into. The gap is now on the wrong part of the pad. Screwing the holder bolt all the way in bows the pad itself outwards.
The solution? Wait six months for pad companies to alter the placement of the gap, buy pads from Shimano or Bontrager or one of the other companies making direct-mount brakes, or, for the DIY types, go at your current preferred brake pad with a file. Simple as that.
Don’t assume that all direct-mount brakes are created equal. Shimano’s version is phenomenal, and Bontrager’s new version is quite good as well (and it’s lighter). But Bontrager’s previous version — the brakes that came on Campagnolo-equipped Madone models last year — were awful, and made worse by the rear brakes’ placement under the chainstays. The only thing that belongs under the chainstays is … nothing. Nothing belongs there.
It is clearly possible to make a bad direct-mount brake, then.
That said, the potential of the design is clear. Brakes can be lighter, stiffer, more powerful, with better modulation and improved tire clearance. All frame brands need to do is design around two bolts, instead of one.
Suggested retail: $170 per caliper; cheaper Ultegra version available for $75 per caliper
We like: Power, modulation, tire clearance, and ease of maintenance and adjustment all in a low-profile, aerodynamic package
We don’t like: Moving the brake pad pin/bolt is just a nuisance
The scoop: If you want to run bigger tires without compromising brake power by going to long-arm calipers, but you don’t want to go to disc brakes, these are a great option.