Analysis: Do disc brakes belong in the pro peloton?

Disc Tour de France

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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 »
About the author: Jason Sumner

An avid cyclist, Jason Sumner has been writing about two-wheeled pursuits of all kinds since 1999. He’s covered the Tour de France, the Olympic Games, and dozens of other international cycling events. He also likes to throw himself into the fray, penning first-person accounts of cycling adventures all over the globe. Sumner, who joined the / staff in 2013, has also done extensive gear testing and is the author of the cycling guide book "75 Classic Rides: Colorado." When not writing or riding, the native Coloradoan can be found enjoying time with his wife Lisa and daughter Cora.

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  • DrSmile says:

    Are we going to have spec bikes like cars in Indy or Nascar to make this work? I’m sure Specialized would pay a pretty penny to be the bike of the peleton for 2016. I’m sure there are lots of corporate opportunities here! Let the market decide I say… while I stop watching entirely and go ride my BSA bracketed aluminum rim braked “oldie.”

  • one1speed says:

    Interesting, both good points of view. I do think they make a lot of sense in wet conditions. especially on long descents. Don’t be fooled, they aren’t going to stop crashes from happening.

    In some ways, I see this purely as a vehicle to try to sell more bikes. Road bikes have been raced for over 100 years without them, and with everything becoming so much lighter and rim brakes becoming better, I certainly don’t see them as necessary.

    This is one of those things that I would call change, more than progress.

  • EmptyBee says:

    The killer rotors image is just way too much of a stretch! I’ve been loving disc brakes for years on my mountain bikes and can’t wait until I can run them on my road bike too.

  • Jody43 says:

    For me it comes down to wanting tubeless. A tubeless tire, spread out over a wider rim, can be run at a more comfortable pressure than a narrower traditional racing tire. According to schwalbe their ultremo tubeless has the lowest rolling resistance of all their tires. It is no secret that rim brakes on carbon rims, which don’t dissipate heat, lead to tires overheating and blowing off the rim on long descents. Disc brakes are what are needed to bring all this together so we safely run carbon rims with the most efficient tires. Stopping in a controlled, quicker manner is a definite bonus.

  • cyclist says:

    As pointed out the only challenges are axle standards and re-learning to do a wheel change. The rest is just resistance to change: weight, too much stopping power, dismembering fingers – really?? I would think bladed spokes would be just as dangerous. I think it is pretty cool that we consumers can ride better technology than the pros, i.e. lighter bikes and have disc brakes.

    • Luis says:

      Funny how that is. No auto driver drives a better car than a F1 racing vehicle. But in Cycling a matures ride better bikes than the pros. The UCI is part of that problem. I understand specs have to be equal but we need technology to help the riders and make racing safer as well as faster. Keeping new technology at bay is a conservative view that holds racers back. I remember when Scott had a bike that weighed 890 grams and the next one up was 1095. The tour made riders use the heavier bike. By the way that is what I ride. I am no racer by a long shot but I can handle my bike well. I enjoy riding. But if I was rich enough I can have better technology than a race team can have.

  • David says:

    How many racing crashes are due to carbon brake tracks? Disc brakes would seem to help the progress of bike technology and reduce racing crashes. Carbon rim brake tracks have always been less than desirable, unless they had an aluminum insert brake track. Hot discs would be a problem, but then so are chainrings teeth, yet disc brakes would reduce the possibility of some crashes. I believe disc brakes are inevitable in the peloton, but it will be a matter of years instead of months. Watch the bike manufacturers push for it, as another marketing exercise, to make your current high dollar bike obsolete.

  • RGRHON says:

    I’d like to see a small polished smooth bead around the circumference in case my face hits your disc, especially with road discs getting bigger (Trek just went to 160mm) due to the higher speeds of road bikes. Please also note that a rim is a 700mm disc! Also, has anyone noticed both Shimano and SRAM recalled their disc brakes due to failure? If UCI is concerned about the Pro Peloton what about all the amateur crits, like class 4-5? I thought pros were better riders with better reaction times than the rest of us? I think the UCI is wise to wait until this stuff works properly. Manu’s only care about today’s profit. UCI is really our only regulatory committee, unless the manu’s screw bikes up royally and we end up with the NTSB involved!

  • dave says:

    It does make sense for roadbikes if it makes sense for mountain bikes, in that the speeds are much higher on the road.

    But now you will have someone braking much faster, and the reaction time of the rider behind will be no faster. = more accidents.

    I personally would not have them on any bike I ride. You look at them and they bend.
    They chatter and rattle down the road. they add weight, cost, complexity.

    I think it is just a style deal. Look ma, I am just like a car!

    I would like to see wider tires mandated. They are no slower and would be alot safer.
    They would also help to bring the weight of the bike up to the 15 # mark. I am tired
    of all the crashes and carnage. This sport is too much of a gory spectacle.

  • Clarence says:


    it’s a bit lame to say that a hot rotor will do more damage than going yourself into a cliff or the fact that the rims [which aren’t similar to a disc brake at all] can’t get equally hot, or that a crankset is dangerous as well at any temperature. its way easier to make contact with a crankset or a security fence bombing a hill than actually touching a 203mm rotor like in a downhill mountain bike. now that i remember, from all the 30-40 crashes i had on my mountain bike bombing down a bike park i never experienced anything like touching a disc brake, be it deliberately or accidentally.
    yes it may sound like magic, but usually disc brake systems are maintenance free. in every sense. you just go check for any bubbles inside the hose once per year.

    people who mark “having to adjust a disc brake in mid race while hanging half body out of the car” really have no idea how a disc brake system works. you don’t need to adjust it. its an hydraulic system, it self aligns. and that’s with today’s models, imagine when we have them perfectly tailored to our road steeds. puff! another imaginary disadvantage gone.

    lets put some facts:

    rotors don’t rattle when installed on a thru-axle interface, as the latter dramatically improves rigidity and structural performance of the fork/rear triangle.

    having a disc brake system means no need of a rim brake track. on VeloNews [i think] i read the amount of aluminum used for create a structurally stable brake track on a rim is about 200-350g, while the average 160mm steel rotor weights under 200g. also, needless to say, manufacturers can expand possibilities on improving the wheel itself, without worrying about some brake pads having to press on the rim.

    using a disc brake system will transfer a considerable weight of the wheel system to the center, making the wheel more reactive since it counts with less rotational mass at the outer parts. and a 1500g reactive wheel feels better than a 1200g wheel with plenty of rotational inertia.

    the difference of weight between a traditional full carbon frame and a disc specific carbon frame is around 150-250g. my iPhone weights more than that. 5 sips of water from a bidon weight similar to that. with today’s disc brakes for road bikes: if you want to climb faster, train harder.

    and yes, i agree the UCI wants to make sure everything on discs will run as smoothly as actual technology, and by that i mean standards and real world usage. i think manufacturers should really decide standards that will be efficient and will apply to road cycling, for example the direct mounting of calipers so it won’t look like [and be] mountain biking technology adapted to road bikes, but genuine evolution of the quality of ride of road bikes, inspired from the fastest and most advanced vehicles on the planet [which by the way have disc brakes as standard]

    i personally think 15mm front thru-axle and 12mm back axle is a great way to improve rigidity and durability of a frame with/without disc brakes, and direct mount looks much much cleaner than post mount like in mountain bikes.

    the only thing i think dave is right about, is wider tires. and that generally is only if it’s on wider rims, otherwise there’s no real performance gain, structurally and aerodynamically speaking.

    people fearing change on their bikes and giving the industry evolution of performance, safety and speed are the same ones that feared the television would kill the radio.

    the best brakes are the ones that let you go faster.

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