Shimano and SRAM are right behind the idea of disc brakes on road bikes — but what about everybody else? We weigh up the pros and cons as professional teams begin testing discs in races

The debate over disc brakes is back in the news as teams begin to test them in the professional peloton.

Starting from August all professional teams have been given the option to test disc brakes at two nominated races of their choosing. With several teams yet to run this braking system, we may see some roll out their disc-equipped race machines at the Vuelta a Espana, including Trek Factory Racing.

We saw Team Sky roll out the disc brake equipped Pinarello Dogma F8 at the Eneco Tour, with Bernie Eisel playing guinea pig.

Eisel riding disc brakes

Eisel said he was “quite excited” to be testing the discs. Photo: Graham Watson

Drop-bar bikes with disc brakes are far from a new idea. Cyclo-cross riders have had them for some time, and for 2015 most major bike brands will have at least one disc-specific road model range, such as Giant’s Defy Advanced, or Specialized’s new Diverge line-up. But with caliper brakes always improving, do road riders really need the compromises that come with a disc brake system?

>>> Pro peloton reacts to disc brakes at Eneco Tour

To begin, let’s look at the three main benefits of disc brakes: power, modulation and all-weather efficiency.

Power

Disc brakes, and especially hydraulic disc brakes, do provide substantially more stopping power than rim brakes. However, a rim caliper system fitted with decent brake blocks has more than enough power for a typical rider on a road bike. So the most likely drop-bar bike type that would benefit from disc brakes, solely in terms of needing more pure power, are touring bikes transporting heavy loads.

>>> Disc v rim brakes – the aerodynamic battle (video) 

Modulation

Modulation is something that mountain bikers talk about more than road riders. It refers to the ‘feel’ coming through the brake system as a rider applies and releases pressure on the levers. Disc brakes do offer better modulation than rim brakes, but then braking on road descents doesn’t involve quite as much finesse as it does for mountain biking. It’s nice to have, but it’s not a necessity.

>>> Just landed: Genesis Equilibrium Disc Ltd 

All-weather assurance

For everyday riders, all-weather ability is a definite boon though. Rims and calipers are a hugely compromised system in the wet, while disc brakes offer very constant performance in all conditions — perfect for British riders especially.

The disadvantages of disc brakes outweigh the advantages; they’re expensive, heavier than caliper brakes, more complicated and raise compatibility issues. Disc wheels are not going to work in your current bikes, and vice versa.

There is also the risk of problems with heat dissipation on long descents. Small discs may not cool down quick enough, heating the hydraulic fluid, and therefore reducing feel and stopping power. However, when they do work well they can offer more stopping power than the tyres can cope with.

>>> Just landed: Wilier GTS Disc 

Are these a big enough turn-off to kill the idea of discs on road bikes?

Legendary bike designer Mike Burrows is sure of what conditions are needed for the technology to flourish. “If the pros adopt it, amateur cyclists will want it, too,” he says. “But will pro riders want to be carrying the extra weight up the side of a mountain, just for better braking on the descent? I think not. Most of all pro riders want to go quicker, not stop better.”

Although he’s a fan of disc brakes – see below – Hoy and Pinnacle designer James Olsen sees practical problems with them within the bike industry, too. “The concept of disc brakes on road bikes won’t fail, although take-up between racers and non-racers will vary. It’s clear that standards in terms of disc mounts and axle types will take time to settle. We’ve seen what unsettled standards did for mountain bike sales: some riders got fed up and held off buying a new bike. We’re in a similar situation with the design and spec side of discs on road bikes.”

Our take

The performance benefits of disc brakes, especially in wet weather, are substantial. But then the cost, faff-factor and compatibility are significant handicaps. If anything, we think more riders will opt for a disc-braked road bike for training, commuting and cycle touring. But when it comes to competition we can’t see those feather-light calipers disappearing any time soon.

Hoy Vulpine_523

Sir Chris’s bicycle product manager is keen on disc brakes on road bikes

For: James Olsen – product manager, Hoy and Pinnacle

“Disc brakes on road bikes are all good in my opinion. Anything that helps riders look to bikes with features that may suit them better — bigger tyres, discs, different riding position, etc — is a good thing.

“Discs free up clearances so that the brakes no longer dictate tyre and mudguard sizing. They’re also consistent in any weather and offer great modulation. The fear of losing control through power versus contact patch and grip isn’t my experience, as modulation is so good.”

Philippe Gilbert on stage four of the 2014 Tour of Beijing

Philippe Gilbert: not a fan of disc brakes on road bikes. Photo: Graham Watson

Against: Philippe Gilbert – pro rider, BMC Racing Team

“For me it is a question of safety. I know in cyclo-cross they use disc brakes, but when we crash we can land on 10 bikes. If you crash and land on a disc, which is warm having braked before the crash, it can open you. Then, if you get it in a vein somewhere…

“You will never have every team on discs, but you couldn’t have some with and some without because that would cause crashes. The ones with discs will brake in 10 metres and the ones without 20 metres.”

The original article by Matt Lamy first appeared in the February 5th edition of Cycling Weekly 

  • Why change what works and certainly in an accidents, noted on recent peleton they can cause large cuts. I prefer the calliper and brake pad system.

  • RIR fan

    I currently have rim brakes and Easton carbon wheels, and Sure Stop yellow pads, which I’ve been told are the best pads available . And I freely admit my bike is unsafe. I no longer ride when it’s damp out because I can’t stop safely. Even a little rain is out of the question. I no longer do rides that include even moderate downhills because, you guessed it, I can’t stop safely. I’m just sitting on the sidelines waiting for disc brakes to become more widely available. Either that or I waste more money on some cheap aluminum wheels for now.

  • brian

    For hybrids would the pros of disc brakes outweigh their cons? I find rim brakes unreliable in the rain and need to be able to stop when drivers run stop signs. Maybe the solution is to have one disc brake instead of two to reduce the cost.

  • Dan Gao

    Oh dear.

    Unlike the road triple versus compact crank debate, which comes down to personal preference, there are actual facts involved here.

    Power – anyone with an understanding of high school physics can tell you that the torque from a 160mm rotor is always 4x WEAKER than a 640mm rotor. That’s right a rim brake is ALWAYS going to be substantially more powerful than a disk brake. Now of course the argument offered by cowed rim brake enthusiasts works for disk brake fans as well – as long as you can lock the wheel it’s good enough. But there are other consequences. Needing 4x the force and having 4x less area as a heat sink means a disk rotor runs much hotter than a rim. The pad material much be carefully chosen to not to glaze and fade (i.e. melt like cheese on a hamburger). This make heavy riders, loaded bikes, and tandems the least appropriate users when many promoter disks as the first choice for such!!!

    Modulation – this is a strange one. The feel of a brake is a combination of the lever throw and the force needed to pull it. As rim brakes have 4x the head room (grip room?) to work with, they can set up the same lever throw, yet be 4x easier to pull. That might not be desirable, contrary as that sounds. Consider the focus ring on a camera – you want a certain heft and feel, not the slickest, fastest action. But what disk fans are telling you is that they like weaker brakes!-)

    All-weather assurance – a clear win for disks. But recreational road riders have been successfully avoiding or negotiating weather with care for decades. We don’t play in mud. And a lot of us haven’t purchased fenders yet;-)

    So, 1 for 3. Not likely to be any more successful than they were last generation.

  • Chris Mann

    I experienced a tire blow out descending a steep grade. The strange thing was my tires were almost new tubeless tires. No tubes and they still blew.

    I think the rims heated enough to loosen the bead that caused the blow out.

    This is why my next bike will be a disk bike.

  • Βαγγελης Σκαρακης

    closed wheels !!!!! in a tour ? what about the wind !!!! come one … although i like idea of disc brake in a road bike

  • Cyrille

    When braking hard, all the weight shifts to the front of the bike, so your front wheel has by far the most grip, and your rear tire close to none.
    Jamming your rear brake so it skids is not the shortest way to stop. The shortest way (by far!) to stop is putting all of your braking effort in the front, almost to the point your rear wheel wants to lift off the ground, no skidding involved.
    This is standard knowledge among motorcycle riders (or else they get killed) and applies also to pedal bikes. But…. you need good control and feeling for this because if you skid your front wheel you fall, or you brake too hard and flip over..
    So the limiting factor is modulation. You can safely use hard front wheel braking with hydraulic disks, and thus dramatically shorten stopping distance. With calipers this is too tricky.

  • djconnel

    GCN has a video describing a test. Discs were better in the wet but not dry where they were about the same.

  • Mick Ayres

    Yea but you have heavy rims to squeeze and weak braking.Just try a hydraulic disc brake bike.You will never go back.I feel is night and day difference.Just like down tube shifters V sti there’s no going back

  • Mick Ayres

    I came down mount teide in Tenerife with rim brakes and the rim was HOT so the burning in a mass peloton is already and problem don’t you think?

  • djconnel

    Except on most bikes sold today running 28 mm tires w/ caliper brakes isn’t a problem. If it is, you go to wider capacity brakes like Pauls or cantilevers. I have 35 mm capacity on my randonneuring bike. It’s an overkill solution if all you want is fatter tires.

  • Mick Ayres

    Mavic and zipp are making real good disc wheels what are you reading.Also because your not squeezing the rim with brake pads you don’t wear through the rims

  • Mick Ayres

    Your wrong !!

  • Mick Ayres

    Yea read the article again.The disc’s mean you can run wider rims and tyres so more traction.I have a Synapse di2 disc with 28c tyres also.The brakes are so good that my caliper braked bikes feel dangerous.Just try a bike with dura-ace disc’s.There is no going back

  • TelemarkTumalo

    When was the last time you saw a new car, motorcycle or mountain bike without disc brakes? Really, roadies are the last to adopt any new technology out of fear. But, really it is about tradition. I’m almost surprised that the rear derailleur was ever attempted.

  • Phillip West

    i don’t ride in wet conditions, i see no other compelling reason for disc brakes.

  • RobTM

    A corroded free hub, due to wet weather riding was reason I needed a new wheelset.

  • RobTM

    To be fair, my disc winter bike’s replacement wheels cost me a lot to have built. I did “go back”. Rim brakes on summer bike, opened up huge choice of popular discounted wheels. I’ve also had to change the pads on Avid BB5’s every few 1000 miles and frequently readjust them. The hydraulics on MTB OTOH, I never needed to touch.

    Mud guard fitting was also time consuming, due to need to carefully bend the stays around disc brake callipers. If you’re not going off road and getting muck on rims, discs have much less going for them. The potential benefit is cheaper mass market Carbon wheels enabled by discs.

  • RobTM

    Disc brakes will eventually allow cheaper carbon rim wheels, as they won’t have to disipate heat from rims and that improves the safety of using clinchers. But for that to happen, there needs to be a significant mass market. Building that road mass market seems to be lubricated with snake oil.
    Off road, discs win out because muck on braking surface rapidly chews up alloy wheel rims and no-one wants to stop mid-ride to do brake maintenance and rim cleaning. Having used cable (Avid BB5) discs on winter bikes, I don’t see significant advantages for typical summer road bike use

  • RobTM

    No one talks about the greater difficulty of fitting mudguards with disks due to caliper being in the way. I’ve some very bent stays, the result works but was time consuming to get right and feels like a bodge. As wet weather predictability is the main advantage of discs, some joined up thinking makes sense.

  • recumbentguy

    Good comment – for those who like better braking.

  • recumbentguy

    Agreed.

  • recumbentguy

    I am sure the extra weight of a disc is easily offset by the rider’s ability. Let’s face it, strategy is even more important on the ‘Tour’ than brakes. Tradition is paramount in most sports – but I am certain discs will make callipers obsolete simply for their superior stopping ability.

  • wallymann

    more power? false. both braking systems routinely and easily lock up, the limiting factor is traction. this is a red-herring.

  • Nope, you are not missing anything. I’ve not had to replace a worn through rim since I started using disc brakes a decade or so back. Which was previously a frequent event MTBing in the Peaks
    Worn rims can be extremely dangerous too, I’ve had a road tyre blow a quarter of the rim off just after some hard braking. Thankfully I was stationary by then.

  • earth

    I think in your argument you have to clarify whether you are talking about hydraulic or cable pull discs.

    I’ve heard the TRP Spyre is a good cable pull brake but so far my experience of cable pull discs is that they are far from the quality of cable pull rim brakes.

    Again cable pull discs are far from fit and forget. They require frequent adjustment and the pads wear very quickly. I’m getting through a set every 1500 miles. I would keep a pair of rim pads about least 6 times as long.

    When they talk about compatibility I think they are talking about the racing scenario with neutral support services. There are compatibility issues due to many standards and those issues have not be resolved yet.

  • Paulx1

    Open Pro -105 is exactly my set up. if I’m worried about weight it’s pounds off my body, not ounces off my bike.

    They also left off if you’re looking for a new bike anyway (like me)- should rim vs disc enter the equation?

  • Patrick O’Rielley

    Agreed, road rash or a broken collar bone is a far greater risk…just not really a worry I am going to have if some riders chose to use disc brakes.

  • jan doeksen

    I can’t believe that there are people who are concerned about sharp and hot braking discs. First off all you can round of the disc so it’s not sharp,secondly they will make carbon disc protectors so you can’t touch the disc when you crash. Plus the body is very well equipped when it comes to touching hot objects….:) Motocross bikes have protected discs. They also have very hot engines and exhaust systems and foot pegs etc.Motocross is a dangerous sport and so is cycling! If I crash my bicycle down hill or in a peloton I would have different worries than my “dangerous” disc brakes.The road will hurt you not the disc brake. What about getting your fingers in the spokes of author bikes?allot more likely to happen! We can solve this with closed wheels!! Do we do this,no because we like open wheels. I have the feeling there are a couple of companies who don’t like to see the disc coming to soon because they don’t have the technology. I’m sure the anti disc people have some kind of relation with these companies.

  • Mike From Spain

    There are lots of disc brake wheels available now. You can always have them made by a local wheel builder.

  • djconnel

    The limiting factors on stopping distance are tire-road traction and the center of mass relative to the pivot point resulting in the rear wheel coming off the road. So more braking power doesn’t mean shorter stop distance. You need more traction of the tires and a lower center of mass.

  • Yoshi Hayashi

    Am I missing something? Isn’t the biggest benefit, not having to worry about wearing the rims out anymore?? That idea alone gets me excited. I’d love to use my lightweight climbing wheels throughout the year, not having worry about wet weather and worn out rims, and consequently having to shell out tonnes of money for a new pair.

  • doctor john

    yes disk brakes have a lot of power instead of calipers and yes
    this could give us confidence etc.
    The fact is that they are hot steel blades inside the least protected bunch of cyclists.
    Road rims will never be stronger than today that they use
    calipers, and tend to fold easily on every crash – sprint inside peloton. Pizza cutters could simulate my point.

    As concern the use of hydravlics instead of mechanical, every one that ever brake with mechanical knows that its an insult to common sense that focus on “how to make road cyclist more depentable from “technology” increasing the cost that they pay to us”. WFSGI (world federation of the sporting goods industry) a federation? really?

  • Grufty Bones

    Rims get worn when used as part of the braking system. I’ve been through a couple. Just sayin. Happy with trad’ campags on my RB

  • Patrick O’Rielley

    What? get into a crash and hit a disc…as if that is your only worry in a peloton crash…not a significant worry

  • MrHaematocrit

    Is there any scientific research on braking distances of bikes people know off?

  • Nathan

    There must be some mountain stages where descending with disc brakes will give a pro rider a serious advantage – especially in the wet. If that advantage was to manifest in a pro race, then it would not take that long for all teams to adopt.

  • Julian Barker

    If you commute on the road amongst cars and in the wet then Yes. Bikes with rim brakes should not be sold for this purpose.

  • mac

    What I was thinking of was the situation where, for example, a wheel breaks shortly before or during a ride. I think most cyclists are far more likely to have access to a traditional style replacement wheel under such circumstances. Either they will have their own spare wheels or they will be able to borrow one. That, I imagine, is what the author of the article meant by “compatibity”: of course it should be no problem to assemble compatible parts if you are building a new bike. The problem comes if you want to mix and match parts from various bikes, which I think most people do at some time or other.

  • Chris

    You caught me in a cynical mood. I really am not such a Luddite. See my previous post.

  • Chris

    If Mr Shimano says that all the teams he supplies or sponsors in the peleton will have disc brakes, they will have disc brakes! Then all the teeny bopper roadies will dash out and buy disc brakes, whether they are beneficial or not, for their application. Us grumpy older roadies will stick with our Weinmann 500’s and Mafac’s.

  • bmxbandit AUK

    Unless you’re racing on the road discs win hands down on all bikes, end of.

  • Guest

    Some of our Mennonite riders use dish breaks for winter riding in Lancaster. They like them, especially with the sand this yare.

  • MrHaematocrit

    I own disc braked bikes and I’m not convinced I need them.

  • mac

    Well that’s very nice for you, but for many cyclists, a quick wheel change can be advantageous, to put it mildly.

    The impression you give is of someone who has rather little experience of cycling and is unable to comprehend that others with more or different experience might see things differently. And your sneery manner is not very pleasant.

  • Rebecca Olds

    I am in the processing of swapping out the front fork on my Surly Cross Check (daily rural commuter) for a Surly Straggler one, to achieve exactly this. (I’d just buy a Straggler to have full discs if I could justify it but my 5 year old CC is so good, it’s worth keeping and upgrading.)

  • Rebecca Olds

    I didn’t say that more braking power is not needed in order to stop in a shorter distance. You said you did not feel you needed more braker power. I said “fair enough, but wouldn’t you like shorter stopping distance?” Of course that requires more braking power. Point being, discs provide the dramatically greater braking power (that you feel you do not need) that make shorter stopping distance possible. The increased confidence this gives you is immeasurable. That’s all.

  • Rebecca Olds

    “The only wheels available are for rim brakes”? Wow, that’s quite a false assumption there.

    The UK is full of wheelbuilders. If I needed a new set, I’d go back to the one who built the ones I have – or any of his colleagues. Any good bike shop should be able to recommend a good local wheelbuilder, if they haven’t already got one in their in-house team.

    Handbuilt wheels need not be expensive. The set on my Engma are Mavic Open Pro rims + Shimano 105 hubs + DT Swiss spokes, cost about £270 for the pair. You can of course spend more but that’s true of factory built wheels as well.

    Meanwhile — without rim wear and barring a crash — I absolutely cannot foresee needing a new wheelset in my lifetime.

  • mac

    Good luck when you need a wheel change then, and the only wheels available are for rim brakes.

  • Henrique Andrade

    Great Comment

  • RT

    How is that going to work? The limiting factor in such a case is the tyres/road, not the brakes. And a shorter stopping distance will always involve a higher braking power.

  • Frederick J Rose

    Short answer: no.

  • Rebecca Olds

    If “more braking power” not needed, then how about dramatically shorter stopping distance? Without skidding.

  • Bertol

    In the space of 14 months I hit the deck twice because of a front tyre blowout caused by the rim overheating. The first time I was doing 40mph and the second about 15, going slowly down a twisty mountain pass. For me disc brakes are a no-brainer.

  • Adam Beevers

    “There is also the risk of problems with heat dissipation on long descents. Small discs may not cool down quick enough, heating the hydraulic fluid, and therefore reducing feel and stopping power.” I suppose he’s never done a long descent with caliper brakes then? In the UK, the longest descent may be only 5-10mins, whereas many other countries have descents that will last for 20-30mins.

    I would like to have a road bike with a front 160mm disc brake and a rear caliper brake.

  • Chris

    I have n+1 bikes, where n=1. My Summer / Dry weather bike has 6800 rim brakes. My winter bike / wet weather (mudguards) has BB7 discs. The discs are better in the wet and will stop you quicker at the expense of extra weight. However overall I prefer the elegance of rim brakes, but horses for courses.

  • Rebecca Olds

    This is shockingly bad journalism.

    So – on power, modulation and all-weather efficiency? Discs win hands down.

    But then — somewhat buried more than halfway through the article, Mr Lamy mentions “cost, faff-factor and compatibility” and, without going into any detail, analysis or comparison, decides that those three “negatives” totally trump the positives. Result – discs are Bad.

    Facts – which Mr Lamy could have investigated and included in his article if he was really interested in addressing the headline question impartially:

    1. Discs need not cost more than rim brake set ups. Shop around. Do your maths.

    2. Compatibility – not a problem IF you know how bikes work and plan your build. (Maybe for Mr Lamy that’s an IF too far?)

    3. Faff – yes, discs can be fiddly to set up and there’s definitely a learning curve (are you willing to learn new things?) but once done, discs are virtually fit and forget since disc pads last so much longer than rim brake pads. And there’s no rim wear.

    I was sceptical when discs first hit the mainstream (Emperor’s New Clothes and all that) but now that I have them on my custom road bike, I will not go back.

    Of course, if you only ever cycle on the flat in dry weather, then the huge benefits of power and reliability in the wet aren’t important to you so if your rim brakes work fine, stay with those. But since CW is a UK-based magazine writing to a UK audience, this kind of shoddy biased investigation, analysis and writing suggests an arrogant disregard for its readership.

  • Steve Jones

    It improved my confidence regardless of the pros and cons, it will happen guys who race will brake later and hold high speeds longer on down hill stretches, if I spanked in at 60kph I don’t think the first thing across my mind is I hope I don’t land on a hot disk!

  • Jerry Hazard

    It’s about $$$, not performance.

  • Eric Blais

    Not once in more than 25 years of road racing I have needed more braking power or even modulation. If I ever jamed the brakes to avoid a car or a crash, my rear tire would simply not grip and leave a skid mark. Can’t see where disk would help when I needed more braking power.

    MTB, yes I agree 100%, Cyclocross I can see the usefulness for mud clearance and mud accumulation, but again braking power and modulation, no don’t see the benefit.

  • John Berry

    The disc brakes debate: are they necessary on road bikes? Simple in the winter yes, in the summer no…what’s the debate? I disagree with the disadvantages, they are no more expensive, Hydraulic is not needed so heat is fade is not an issue.

  • James Hart

    Sure discs weigh more than rim brakes, but is that really an issue? Numerous bikes available already weigh less than the UCI minimum… a little ballast that improves some aspect of performance seems a good trade-off.

  • Cullipool

    … and it makes such nice money for the equipment manufacturers.