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In The Bunch

Don't expect change to come right away, but we do see a day when the pro peloton will be populated with disc brake-equipped road bikes. Photo by Graham Watson

Consider this hypothetical situation: It's the waning moments of a critical mountain stage at the 2015 Tour de France. Rain is cascading down in buckets. A lone leader crests the final climb, facing only a long descent to the finish, which is situated in a small town at the base of the mountain. The road is steep and twisty. Our lone rider's bike is equipped with a set of lightweight carbon fiber wheels and traditional rim brakes.

What happens next may have as much to do with luck (or bad luck) as it does with skill. Our imaginary rider might win the stage - or he might take one too many risks and plummet off the side of the road. For as any cyclist knows, no matter what the manufacturers tell us about special brake tracks or revolutionary brake pad compounds, using rim brakes to slow down rain slicked composite wheels is risky business.

"When it rains you definitely feel a lot less safe on carbon wheels," admitted Zak Dempster, who rides for Team NetApp-Endura and finished 152nd at this year's Tour de France. "A lot of times you pull the brakes and nothing happens right away. Then you start slowing down. I would certainly like to see something more reliable."

That something, many would argue, is already here: disc brakes. They're not impacted by wet weather conditions and have been the standard on mountain bikes for years. They also allow users to run wider tires, which typically provide better traction and have lower rolling resistance.

Disc brake-equipped road bikes also making rapid inroads in the general consumer market. Shimano and SRAM both offer road-specific disk brake component packages, and nearly every major bike manufacturer has a least one model spec'd with a disc braking system.

Descending Wet Weather

Long descents, especially when roads are wet, are two of the big arguments favoring disc brakes. Photos by Graham Watson

In mid July, Giant launched it's new endurance-oriented 2015 Defy line, and all but the low-end alloy models are equipped with rotors. That move from the world's largest bike maker seems a clear indicator that change is in the works at the sport's highest level.

"There was supposed to be a meeting to discuss it the day before the Tour de France started, but then it got postponed to Eurobike," said Jon Swanson, Giant's global road category manager, referencing the cycling industry's largest trade show, which is held in late August in Friedrichshafen, Germany. "But it's no secret that there is an ongoing conversation around disc brakes between the industry and the UCI (bike racing's world governing body) about when and how they are going to be implemented into the WorldTour. It's coming. There just needs to be a date and an agreement amongst all the manufacturers involved in terms of tolerances and fit and finish. And of course that's hard to nail down."

Swanson believes the 2015 season is too soon. His guess is 2016.

Now consider another hypothetical: It's the final kilometer of a first-week sprint stage at the 2016 Tour de France. The yellow jersey awaits the day's winner. The bunch is all together and flying. Wheels touch. A dozen riders tumble to the tarmac. Bikes and bodies pile on top of each other. As any cycling fan knows, it's an all to frequent scene in the world of professional racing.

Now add to that equation bikes equipped with disc brakes, rotors heated up from the braking required to negotiate a chain of roundabouts that precede our fantasy final dash to the finish. We wont paint an overly macabre scene. But it doesn't take a wild imagination to conjure up images of what hot metal discs could do to human flesh.


What happens when there's a huge pile-up and bikes (and rotors) are flying around? Photo by Graham Watson

"That's just one of the reason why I think it's a horrible idea," said Alex Banyay, a mechanic for Garmin-Sharp, which finished 19th in the team classification and had one stage win at the 2014 Tour de France. "You have 15-20 guys in a crash and you have discs flying around, somebody could lose a finger. It's also possible I could lose a finger trying to do a wheel change. It's also possible I could knock out one of the pads while trying to do a wheel change. It's also possible I can't even get the wheel in when trying to do the wheel change."

Banyay clearly resides at the cynical end of the technology spectrum, but all his points contain at least nuggets of validity. There's no way he could lean out a team car window and make brake adjustments to a disc-equipped bike. Banyay also could have mentioned the extra weight current disc brake systems add (200-300 grams), and the lack of a consistent axle standard for the current crop of disc-brake equipped road bikes.

Continue to Page 2 for more on the disc brake debate, and why the end of the UCI weight limit could be near »

Weight Issue Disc Brake Defy

Despite a small weight penalty compared to traditional rim brakes, Giant choose to make significant investment in disc brake technology with its new Defy endurance road bike line. Photos by Chris Milliman

Giant stuck with traditional quick release set-ups for its new Defy line. Other manufacturers have opted for thru-axles, some 12mm, some 15mm. Some use both, such as the new Mares cyclocross bike from Focus. But variances like that simply don't work in the professional peloton, where neutral service providers such as Mavic need to be able to take care of nearly 200 riders, but don't have the cargo capacity to carry dozens of different set-up wheels.

"Right now there are multiple conversations happening between a few of the big brands and everyone is talking the same talk," explained Giant's Swanson. "We all know that for the technology to be embraced by the highest level of racing, there has to be a consistent standard and it needs to have quick release functionality so that you can change wheels on the fly."

Swanson's choice would be 12mm thru-axles. "That gives you some added stiffness so you could remove some of the extra frame material from the fork leg," he said. "That will help keep the weight penalty in check."

Heretofore, that weight penalty might not necessarily have been a major issue in the pro peloton. As it is right now, most team mechanics are forced to add otherwise-unnecessary weight to bikes just to stay within compliance of the UCI's 6.8kg (14.99 pounds) weight limit. But with new bikes such as Trek's ultra-light Émonda line coming to market, perhaps that rule could see amendments soon as well.

"Bikes should weigh however much [the manufacturer] wants them to weigh, provided they have all the commercial safety certifications," said Swanson. "If it is fit enough for sale it should be fit enough to race."

To wit, the Trek Émonda SLR 10 has a claimed weight of just 10.25 pounds, and a size 60cm test model Émonda SLR 8 equipped with alloy wheels that just showed up at the RoadBikeReview offices weighed 14.1 pounds without pedals. But no bikes in the Émonda line come spec'd with disc brakes.

"We don't see a lot of demand on race bikes," said Trek road product manager Ben Coates, whose company does spec discs on some of its Domane endurance bikes.


Adoption of disc brakes in the pro peloton will require that the industry adopt some kind of axle standard in order to make wheel changes fast. Photo by Graham Watson

But might that attitude change if the UCI changed its tune? Swanson believes so, and says the recent regime change at the UCI has resulted in more openness to technology rule changes. "[Since Brian Cookson replaced Pat McQuaid as UCI president] the attitude has been much more positive and progressive, which is really important to the industry," Swanson said. "Sometimes manufacturers aren't willing to pull the trigger on new technology because you need racing as a marketing vehicle."

Clearly, though, disc brakes are not falling into that well. Like Giant, Specialized has gotten behind the idea despite the lack of UCI approval, launching multiple rotor-equipped bikes, including some Tarmac models, which made it one of the first manufactures to spec disc brakes on a race bike rather than only endurance geometry frames.

"We are full gas on disc brakes," said Specialized spokesman Chris Riekert. "It's something we see as more than just a wet weather advantage. There's so much more available braking power and when you mix the race geometry of the Tarmac with that extra braking and you have a really diverse weapon. At the same time, I think it will take a while before it catches on in the pro peloton. When the weight comes down and you have enough wheel options, that's when you'll see that switchover."

"Right now I just don't see disc brakes being to the point where they are ready for racing application," added Jonathan Vaughters, general manager of the Garmin-Sharp team, who race on Cervélo, which has yet to offer a disc brake-equipped road bike. "But I'd guess all those bugs get worked out in the next few years. Than at that point you can concentrate on making the rim better structurally and more aero without worrying about the braking surface. Right now it seems like wheels either have a great braking surface but are kind of heavy, or they are super aero and light with a shitty braking surface. When you bring all that together, things will change."


Team cars can only carry so many spare bikes and spare wheels.

Most argue when that change does comes, it must be universal across the pro peloton. The notion of some riders with disc-equipped brakes riding in close proximity to others who are still running rim brakes makes people nervous.

"If everyone doesn't have them then you're going to have a lot more crashes because they stop differently than normal brakes," said BMC Racing's general manager Jim Ochowicz, whose team finished fourth in the team standings at this year's Tour. "If we do it, it has to be all in, not half half."

Swanson counters that International Olympic Committee rules could make an all-or-nothing proposition untenable. "IOC rules say you cant have mandatory technology like that so close to the Olympics, and 2016 is an Olympic year. So it might have to be a mix at first," he said. "But for me the larger problem is that right now we are still using modified mountain bike technology. Once UCI approval comes, you'll see all the manufactures focusing on road and that will get the weights down quickly and adoption will follow."

It would appear then that disc brakes are eventually coming to the pro peloton. But do they belong there? We give the last word to NetApp's Dempster, whose sentiment, while not universal among his pro tour peers, is shared by many. "I've ridden mountain bikes with disc brakes and you just stop faster," he said. "I just don't see why stopping faster would be bad."

What do you think? Do disc brakes belong in the pro peloton? Sound off in the comments section below »