Photography by Wade Wallace

Disc brakes and road bikes: what does the future hold?

by Wade Wallace

If you’ve been paying any sort of attention to what the major manufacturers have been doing in the past year or so, you’ll notice that disc brakes are becoming more of a fixture on road bikes. This is not a passing fad.

SRAM and Shimano released hydraulic disc brakes earlier this year and if this year’s Interbike and Eurobike are any indication, we’re starting to see high-end road bike manufacturers take disc brakes seriously.

So is it only a matter of time before we see the pros rolling around with bikes equipped with disc brakes? Are all your sets of wheels going to be rendered obsolete in the coming years? And what’s stopping all this from happening now? We spoke with the UCI as well as industry experts to find out what the future holds.

It’s pretty clear that the industry wants disc brakes to take off. They are a new means of differentiation and they require new wheels, new hubs and new frames, all of which means more stuff for consumers to buy. But it’s not only that.

I’ve had the pleasure of riding a Specialized Roubaix S-Works with disc brakes in recent weeks (review coming tomorrow) and I was astounded at the braking performance advantage.

For those of you familiar with the transition to mountain bike discs, you’ll remember how this technology revolutionised mountain bike riding. Braking is simply better compared to traditional brakes and there’s less rim and brake-pad wear. Even in dry conditions the braking is noticeably better and more reliable on discs. The industry likes to describe this as braking modulation — the way the braking “feels” and how much fine control you have when squeezing the brake levers.

Having disc brakes also also means that heat dissipation on the rims is no longer a problem — something that is an issue with carbon clinchers. With disc brakes you can have all the benefits of a carbon clincher, but with a lighter rim and better and more predictable stopping power. Also, when a wheel comes seriously out of true, braking isn’t affected when you’re running disc brakes.

Industry impressions

Shimano launched Ultegra disc brakes for road bikes earlier this year. I asked Shimano’s Australian Product Manager, Troy Glennan, where he thinks disc brakes are headed when it comes to road bikes. Note that Troy’s opinions don’t constitute an official statement from Shimano; they’re just his thoughts about where things are headed.

“

“Rim brakes will always be there, but the biggest factor is what the UCI does with it. From a safety point of view, I’m not sure that’s going to happen for a while. When you’ve seen guys crash mountain bikes and put a rotor through their knee, it’s not pretty. Throw in some of those crashes you see in sprint finishes on the road …

It will come down to a point where the UCI would have to make a rule where everyone uses one braking system or another (everyone uses discs, or everyone uses calipers) because of different stopping capabilities.

You’ve seen bike companies produce bikes like the Specialized Roubaix or BMC Gran Fondo — you can see that it’s not aimed at the race market as of yet. This is where it’ll be targeted at for the next few years.

Shimano doesn’t see this as just a fad and I think that there’s a spot in the market for a completely different category of bikes using disc brakes. [But] I can’t see caliper brakes vanishing and becoming obsolete.”

I also spoke to Rob Eva, Head of SRAM Australia, about the future of disc brakes and his take was quite different to Troy’s:

“

“I disagree that disc brakes will only be part of a category [of road bikes]. Do you see a ‘category’ of mountain bike that only had disc brakes? No - you can’t find a mountain bike with rim brakes anymore.

I see all bikes evolving to disc brakes. I remember back in my mountain bike days there [was] the same resistance. I think the change to road disc brakes will be swifter and more strategic than it was to mountain bikes.

The reason I think that is because carbon rims (full carbon clinchers) are such a safety issue with all these newcomers not knowing how to brake. Essentially it’s become a safety issue to run a rim brake on a carbon braking surface. The braking power is not good enough.

People who criticise disc brakes have not ridden them. For those people who want to stand by ‘tradition’, I say that there’s lots of things that are ‘traditional’ in road cycling. Taking drugs is ‘tradition’, but you know what? That has to change as well.

Tradition doesn’t mean anything when it comes to performance and safety. We’re trying to take weight off the tyres, off the tubes, off the rims, off the wheels, and it’s got to give somewhere. I think we’ve come to the point where it’s starting to give, and we gotta put that weight back, be safer, and put a decent set of brakes on that will work.”

So what does Rob Eva think about the idea that a shift to disc brakes is merely an industry push to get cyclists to spend more?

“

“We’re not forcing anyone to upgrade to disc brakes. Yes it is a bit of a fashion, but it’s a necessary performance fashion. It’s a huge advantage that I think is worthwhile. We’re designing disc brakes, but we’re not the ones who make the decision to put them on every frame. It’s the frame manufacturers who come to us and ask for discs.”

Disc brakes and the UCI

The UCI’s technical regulations currently don’t allow disc brakes to be used in road races. We spoke with the UCI’s Technical Collaborator Johan Kucaba about whether that’s likely to change any time soon.

“

From the UCI point of view, the disc brakes are still considered as a technical innovation, and therefore they are still not allowed in road competitions. However, for some time now, we follow the development of these new brakes, and the subject is discussed within the UCI Equipment Commissions.

Johan was quick to point out that most of the current road bikes that use disc brake are using brakes designed for cyclocross or MTB and that road-specific disc brakes are needed to handle the unique nature of road cycling.

“

“The main differences and challenges to be resolved are:

• higher speed
• longer braking time
• higher temperature accumulation
• bigger disk which means bigger safety issue in case of crashes
• braking behaviour that may block the wheel and make the bike slip
• difference of braking performance between disc brakes and rim brakes that may cause crashes inside the peloton.”

Until now the UCI has only received one request from a manufacturer to allow disc brakes in road racing. After careful consideration from the Equipment Commission, the braking system was rejected because it “did not fulfil … all the above requirements and did not provide all the necessary guarantees for safety”.

But, as Johan reiterates, the UCI is receptive to the development of disc brakes for road racing.

“

“We are therefore in contact with manufacturers, and follow the development of these braking systems. Moreover, we encourage the industry to develop these braking systems.

The decision to allow disc brakes in road competitions could be taken when a manufacturer will provide us the sufficient elements that prove that his brake system fulfil to all requirements and that it is adapted to the use in road competitions.”

At that time, the UCI Technical Regulation will need to be updated, meaning a one-year delay before they’d be usable on the road. And to allow the industry to adapt and ensure fairness for all teams and riders, an extra one-year delay would likely be applied.

“With the Olympic year in 2016 (and therefore no modification in the regulation that year), it is unlikely that the disc brakes are allowed in road races until 2017”, Johan said.

Shimano Ultegra disc brake.

Rob Eva from SRAM argues that the decisions made by the UCI will have little effect on everyday cyclists.

“

It really doesn’t matter what the UCI says. They’re only a small part of cycling and there are a lot of people out there who don’t care what the UCI is nor do they give a damn. They just want to ride their bikes. On the road racing side of things, the UCI will play a part in it, but it’s not going to be a huge part.”

In many ways, Rob is right — there’s nothing stopping manufacturers from making disc-brake-equipped road bikes for the consumer market, and nothing stopping riders from doing club rides, gran fondos or other non-UCI-sanctioned events with disc brakes.

Other challenges

Even if disc brakes were to be introduced into the pro peloton next year — which we know they won’t — there’s still a handful of issues that need to be resolved.

For a start, there is no industry consensus or standard on what size of disc brakes to use. Shimano’s rotors use the company’s ICE Technology which allows a 140mm rotor to be used (front and rear) without worrying about heat dissipation. Rob Eva from SRAM recommends a 160mm rotor on both front and rear (SRAM offers both 140 and 160mm rotors). Ultimately though, the frame manufacturer is the one who specs the rotor size.

And then there’s the aero-craze going on at the moment in the industry. The trend right now is that everyone is producing aero road bikes (not to mention aero helmets, shoes, jerseys, etc). If you go and stick a disc on an aero bike, then any aerodynamic advantage is likely jeopardised. At the highest level, all the manufacturers are incorporating integrated frame braking to get the best aero advantage.

Final thoughts

Road racing is steeped in tradition and I think it’s safe to say that roadies are not early adopters of new bike technology. Mountain bikers and triathletes are the exact opposite. Personally, I’m a big supporter of innovation because it is innovation that eventually leads to progress.

Just like Di2 electronic gearing or the iPad, disc brakes for road bikes don’t appear to be filling a real need — existing braking technology does a very good job. But like Di2 or the iPad, once you start using disc brakes, you’ll wonder how you did without them.

What do you think? Are hydraulic disc brakes the next big advancement in road bike technology? Or is this solving a problem that doesn’t exist?

Tags: disc brakes, Shimano, SRAM

George

I will go for the integrated frame braking system. I like the stealth clean lines look and I want more aero not brakes.
- Robert Merkel
  
  This.
  
  For general riding, sure, I’d prefer the much smoother feel and safer failure mode you get from discs. But for racing, I’ll take speed every time.
  - RayG
    
    Being able to brake later into a corner = speed. Any weight penalty can easily be made up elsewhere on the bike. Aerodynamics is another matter.
    - jules
      
      trying to brake late into a corner is a good way to crash. slow in - fast out. works in motorsport and applies even more to cycling.
      - Dave
        
        Braking later for the same corner entry point and speed is always going to be an advantage though.
      - velocite
        
        In a race car the driver has enough power under his foot to break adhesion at any time on the way through or out of the corner, so keeping the car under control and modulating the throttle is the way to go. With a bike the ideal is to waste as little foward speed as possible at every point leading up to and through the corner. Jobst Brandt even argues that the optimum involves braking through the corner, but given the skill required that idea seems largely academic.
        
        jules
        
        my motorsport comparison was flawed. with bikes, i was referring more to the risk of losing control on entry to a corner, where bikes are at a disadvantage. enter a corner too hot, and you will likely crash. in a car, you can do all sorts of stuff which the 4 wheel stability will forgive you for. braking late on a bike is definitely quicker, but it’s riskier.
        
        RickH
        
        Correct.
        
        Paul Jakma
        
        Your analogy wasn’t flawed - motorsport covers motorbikes too, which have similar dynamic cornering behaviour to bicycles.
        
        Now, in racing in motorbikes, late braking actually is a huge competitive advantage. Motorbikes also have bigger tyres and suspension. That said, the current MotoGP world champion, Jorge Lorenzo, is renowned for /not/ braking late, but instead being smooth and fast throughout the corner.
      - Tim Watts
        
        Depends entirely on the bike - eg the Honda RC213V is a slow in, fast out design, whereas the Yamaha M1 needs to carry more corner speed. Also, braking hard in a straight line is not the problem, trail braking is what loads up the front tire and is the #1 cause of front end tucks, aka low siding, aka crashing. The greater level of control from a good hydraulic disc will help elite’s ride the fine line
      - Lechu
        
        Where does it contradict? With disc brakes you are able to brake later but still have same speed on entrance of the curve as on rim brkaes. It means that you save time just before the turn starts.
      - RickH
        
        Wrong.
Offtheback

I have road bikes and mountain bikes. My mountain bikes have disc brakes. And I have ridden a rim brake equipped road bike down a long and winding 15% hill in the pouring rain a few times. I’d have disc brakes on my road bike then, and any other time as well. They simply work better in the dry or in the wet, are easier to use (less fatiguing on the hands), require less maintenance (although the maintenance they do require is a little more substantial), are cleaner and are easier on the rims.
Kevin

No in many ways Rob is wrong and just trying push his brand because they want it to succeed. If the UCI don’t do it then it won’t happen. Maybe a couple of punters will want it but they probably ride Sram already.
- Damien P
  
  There are a lot of CX-style general use/commuting/touring bikes around but, and these would go really well with disks.
Rosco

I just can’t see it happening at an elite level for a while.
Until disc brake equiped wheels can be made as light as current high end tubulars I won’t be spending any money on discs.
Sure I can see performance benefits, but not at the cost of speed thankyou.
mcr

disc brakes are good - but i think better mechanical disc brakes might be the best middle ground for it…. better stopping power than rim brakes - yet compatible with existing levers -
As for wheel standards - the manufacturers must come out with unified standards /dimensions - like 132 hub spacing rear - even an carbon frame could fit that ( 1mm extra each side) - rotor size and placement, between chain and seatstays or above seat stays? front wheel minimum spokes and lacing order.
I think the biggest impact to the consumers is the frame and wheels that they currently have - most will be rendered not compatible - metal frames (steel, Ti. Al) could be re-jigged or welded to have the mounts - but carbon frames….
- jules
  
  have to disagree. hydro is brilliant - why compromise?
  - Dave
    
    Agree. I like it just as much for the ease of service as for the better performance, and that’s even without the annoyance of servicing internal cable routing.
  - KCR
    
    For touring applications, cable actuated brakes are more easily serviced in the middle of nowhere, especially when strapping bags to the front of the bike (things pressing against the hydro lines can let air in to the system). Hanging the bike upside down for long periods of time can have air float in to the caliper too if you’re unlucky.
    
    Outside of that, I’d rather have hydro any day.
- Dave
  
  I agree. Road racing requires a unified standard because of the requirement for race organisers to provide neutral service. Once a standard is in place the big players in the industry can present a united front to the UCI and threaten a breakaway league if discs aren’t allowed - the UCI needs the industry a lot more than the industry needs the UCI.
  
  As for older bikes, the same thing will happen as every other time a new standard has come along. Some consumers will stay with their old bikes, some will upgrade immediately.
jules

i think there’s a more fundamental question - is better braking always good?

in road racing, where you’re in tight bunches, i’d argue it can be dangerous. i’ve almost been put in hospital by someone who got nervous and hit the brakes on a fast downhill bend. would more powerful brakes help there? i’m skeptical.

on the other hand, for races which have long downhill sections, such as the Tour, you’d imagine brakes with better power, modulation and which don’t melt the rim can only be good. those guys don’t make as many rookie mistakes - as above - either.

the key benefit of disc brakes is really wet weather riding - when rim brakes just don’t work.
- haitch
  
  “those guys don’t make as many rookie mistakes - as above - either.”
  
  Except for Geirant Thomas.
  - jules
    
    is this a ref. to sunday’s race? :)
    - haitch
      
      Not even that, he fell off during San Remo, Flanders and Paris-Roubaix earlier this year!
- Dave
  
  The better modulation and control of disc brakes compared to rim brakes which are on or off should be an advantage for big bunch rides.
- Marcel
  
  The principle seems sound in theory - more powerful braking leading to more erratic braking- but in reality I dont believe it will be an issue.
  Skilled riders modulate braking irrespective of system. The rookies will be erratic similarly but perhaps with discs and easier and more controllable braking may in fact have more confidence and do the opposite.
  Rob Eva is right. Resistance comes from hang ups and inexperience. The majority of riders on the road who dobt compete in sanctioned events will love the huge improvement that discs provide. Our dream of tubular weight carbon rims with perfect aero and wide beads without the white knuckle wet weather braking sketchiness can come true. I look forward to attacking on the descents - see this years world champs - and doing so in any condition on any grade with confidence. The future is here for those who want it.
  
  But there should be no reason to change if you dont want to. Alu rims with da calipers and swiss stop pads will work near as the same if you know what you are doing. Its all good !
Tim Watts

I have a road bike, a TT bike and a mountain bike. By far I prefer the braking power and modulation provided by the disc brakes on my mtb. Rim brakes are old technology and are inferior to disc brakes in every performance category except weight. I can’t wait until I can get a road bike with a hydraulic disc setup on it!
- Dave
  
  Even the weight issue will get sorted out soon. The extra freedom with rims not being required to act as part of the braking system should allow lighter rims for disc wheels, and if you’re still left with a weight penalty at that point there are plenty of other parts on the bike that can go on a diet to fit in the disc and still get down to just scraping over 6.8kg.
  - JimmyMatamata
    
    Maybe. All the braking torque is being applied at the hub on a disc brake. The rest of the wheel (spokes and rim) may need to be stronger to handle the forces involved.
  - scottmanning
    
    Didn’t I read on here a rim manufacturer saying disc specific, clincher, full carbon rims, are no lighter (not much) than the current rim brake rims? You have removed the issue of heat, but the rim still needs to retain the tyre and that is the source of most of the weight.
    
    A diet to the rest of the bike? I’d love to know what part of a bike isn’t already trimmed to the minimum?
- velocite
  
  +1. From my distant perspective the UCI seems like an anachronism. Their arguments against discs, if they can be called arguments, are risible. Better brakes are more dangerous? Get out of it!
  - RayG
    
    Yep. No-one ever complained their brakes worked too well.
    - scottmanning
      
      Sure they did. In motor sport is a perfect example of the constant balancing act. Too much bite, not enough modulation etc. Get a brake working very well and you end up with wheel lock-ups and massive heat distribution problems = bigger disc = heavier etc. There is always a balance to be found here.
Ross

So why are disc brake equipped road bikes deemed to be safe enough to use in sportives but not in racing? Yes, I know UCI has no control over sportives but does this mean that sportive riders are more skilled and more in control (!) of their bikes than road racers and that they are also somehow impervious to disc rotors slicing off their limbs?

I guess until when/if UCI appove road disc setups bike manufacturers are having to bring out two seperate models, one with discs and one with rim brakes which could lead to prices of bikes increasing due to decreased volume of manufacture.
- Captain Buckfast
  
  “So why are disc brake equipped road bikes deemed to be safe enough to use in sportives but not in racing?”
  
  Although I can think of a few reasons, I don’t think it’s that simple. Possibly greater legal implications and potential litigation when it comes to both amateur and pro racing.
  - Dave
    
    UCI over-regulation.
LeeRoy

Commuter use only. They just don’t look “pro” :-)
- Marcel
  
  Perhaps not now but do MTBs with v brakes look PRO to you ?
  - LeeRoy
    
    No they don’t, but then again no MTB looks PRO to me. They just don’t have the beautiful lines that a road-bike has. Obviously very subjective.
    - Dave
      
      Yes, because mass-produced cookie cutter DF road bikes are *sooooo* interesting to look at. Seen one you’ve seen the lot.
      - LeeRoy
        
        Some assumptions there but anyways I still think that mass-produced cookie cutter CF road bikes still look better than mass-produced cookie cutter MTBs.
- Dave
  
  I guess a nice graceful slide straight on at a wet hairpin looks “PRO” to you as well.
  
  As the technology goes mainstream on road racers, nicer looking designs will come and in a few years you’ll be laughing whenever you see old rim brakes.
  - LeeRoy
    
    I can see the advantages of discs on a fast descent but sliding out on a wet hairpin is usually due to poor technique or excessive speed.
PatFitzy

After seeing the number of high end bikes at Eurobike with discs, it’s not a question of “is this is going to happen”, it has happened already for 2014 bikes.

Pro tour is the Formula 1 of the bike industry, but the general riding population will have access to better/safer equipment than the pro’s. Things will change quickly as they wont want the general population to toddling about on F1 equipment that the pro’s cant have.

On a side note for womens cycling, disc brakes will dramatically change confidence levels for many gals in the descending dept. Discs don’t require as much strength or force from the hands and arms on long steep descents.
- Dave
  
  No, mountain biking is the F1 of the bike industry, every innovation goes through there first before coming to road racing. Road racing is so ridiculously over-regulated that it’s more like V8 BoganCars in the technical side of things - fast, but conservative and behind the times.
  - Marcel
    
    And honestly how can a min weight regulation trully reflect safety? . The UCI,
    The Ostrich.
    - scottmanning
      
      Easily, I’ll give you just one example; alloy skewers. They are extremely light but prone to snapping. I agree it’s true that each component manufacture does it’s best to make it’s component as light as possible so at the end of the day the limit does nothing to ensure safety of the assembled bike.
DingoMan

These things are meat slicers attached to each wheel. Google “bike disc brake finger cut off” and you see what these things can do.
- Matt de Neef
  
  No thanks.
- Marcel
  
  Muppets will pucture fingers between chain and ring too. Darwins theory has failed modern humans.
- velocite
  
  This is nonsense. I just Googled as you suggested and the result is stories of drunks and dickheads. For instance “I spun the back wheel to check the rear disc rotor. Somehow i stuck my finger in…”
  
  Not a serious consideration.
  - bigwagon
    
    It will be a serious consideration when someone gets half their lower leg sliced off in a field sprint pileup like a meat slicer
    - velocite
      
      I’m thinking jockey wheels could be dangerous. Imagine if your testicles got tangled up in the derailleur. Now that would be serious…
echidna_sg

just like ABS brakes in cars - for a few years there was a steep increase in rear enders where the ABS equipped vehicle in front has far better stopping power than the non-ABS vehicle behind… but people learn to adapt or they join the herd. I can see mass pileups in bunches due to the odd disc equipt bike in a pack out-braking everyone else….
- runrider
  
  The same thing happened in the 1990’s when dual pivot brakes came in. Crashes in races began happening when riders started to lock up their bike when the bunch slowed during a race. With the older single pivot brakes you tended to slow but not stop as quickly. Dual pivot stopped you dead and the riders behind couldn’t react fast enough.
  So now that we have disc brakes, carbon wheels & electronic shifting - all that’s left is putting engines on push bikes like the invisible one Fabian had a few years back. Personally I think the UCI was right in making a track pursuit bike a “BIKE”. Hopefully it wont be long before there is a break away form of racing using steel framed bikes with 6 speed sprockets, down tube shifters and brakes with exposed cables again.
Tim

Hydro disc brakes (not cable) are the future. This talk of safety from the UCI is without basis. I distrust any reference to safety from the UCI. Consumers will lead the drive as they have in mountain biking. Consider change to 29 and now 27.5 inch wheels. Performance matters. Can you imagine your local club telling you to go home if your bike has discs? No - they need the numbers. My bike is due for replacement. I am now holding off until I can get a beautiful racing frame with disc brakes.
- Robert Merkel
  
  Can you imagine your local club telling you to go home if you show up on a tri bike for a road race?
  
  Bloody oath you could.
  - Tim
    
    Im not convinced that the comparison is fair. However, I would still rock up and test it out at the local race and see what happens.
- jules
  
  mate they tell you to go home if you have the wrong sticker on your helmet
  - Tim
    
    My helmets have never been checked in a road race. Have been in a mountain bike race though.
Neil

I think these could end up being a bit of a horses for courses type system. If I lived in a fairly flat area, I’d want aero, integrated brakes. If I was doing a lot of climbing (or more importantly descending), discscould be worth the coin.
I could potentially see one setup being used at pro level for flat stages, and another for mountains. Throw hydraulic rim into the mix and you have another option.
Clarence Laboranti

I think i’ll be convinced until i’ll try it. yes, i’ve tried hydraulic disc brakes on a mountain bike and it feels way more effective than mechanic rim brakes, and i’ve that’s bombing a fast and rocky downhill section on an enduro trail with 203mm front rotor and 185mm back rotor.

It does brake better, but a road bike has a different geometry, different turning response rate, different stiffness to weight ratio, even different terrain and use. this obviously means a different way of using a braking system which is designed to satisfy a certain criteria conforming to a range of riding styles [MTB, Cyclocross…] applying a MTB braking system to a road bike [or to a road ride better said] right now sounds like putting a Rally car spoiler to an F1 [it may work but maybe just not as it is supposed to?]. the hydraulic disc system may have a better or more concrete deceleration curve and modulation on a road bike, but there are other aspects that should be at least same or superior than the old school, traditional, but well adapted and perfected current braking system road bikes have now.

I think rotors on a Road frame it will most likely work and get official, just maybe not now. i’ll definitely will love to test ride a Bianchi with rotors anyways!

Out of the question btw, wonder what will Campagnolo do as a response to these technologies. im aware they designed some 35mm carbon rim brake wheels with a special finish that lets the rider brake in harsh wet conditions as if it were top quality aluminium on dry conditions. I just hope that if they decide to create hydraulic braking system that their sublime perfectly beautiful curvy awesome brake/shift levers won’t get that ugly ass absurd deformation the SRAM shifters suffered. just saying.
RayG

Anyone that’s ridden disc brakes in wet mud knows that some disc brake pads aren’t any less susceptible to wear than rim brake pads. Maybe even more so. But at least you’re able to stop when you want to with the discs, not several rim-drying rotations of the wheel after you want to.
If the UCI is worried about the differences in braking behaviour in the same peloton, they’d better outlaw the SRAM hydraulic rim brakes that Cav loves so much.
- RayG
  
  Actually, I’d have said they should also ban carbon rims in the name of equal braking, but I wouldn’t want to comment on technology I haven’t used.
dcaspira

If they nailed - a lightweight set for climbing cols, that removes the current compromises when descending - i.e maintaining brake temps / glue, slowing down during fun sections etc - then I buy a disc bike, no brainer.
Philipp Forstner

I think we all agree that Disc brakes are better breaking performance, I am just questioning if you really need better breaking performance that often…the main problem I see is, that first off all the whole peleton needs to change to discs or there gonna be major crashes due different braking speeds…and the other big issue will be changing flat wheels…changing a disc wheel is not that fast and easy and often the brake needs to be readjusted as far as I know…but thats about UCI races…

the other issue is with all the other small races, amateur UCI races…where no pros are competing. so that’s also a couple of riders who cannot change to discs…and also a lot of people got different wheels setups at home, for mountain, flat stuff, training, winter and so on…you would need to change all those wheels…also TT wheels won’t be compatibel with for example your Crit Setup. And also nobody things about the safty issue in Gran Fondos like the “Ötztaler Radmarathon” where is just going up and down and where Discs would make sense (especially this year)…but 4000 people crashing down Kuetal with 40k on wet conditions and all together different breaking speeds into the first corners…or those tours like Transalp, Big Break, etc. That really is an safty issue…

Also I am not sure, if the hubs and forks around discs are strong enough to hold the weight of a heavy guy like 100kg+ on a descent like the stelvio…this just sounds like more safty than a carbon clincher rim break…

and all that, weight discussion, to get rims even lighter…do we need this really? and just to safe weight and than we are putting heavy discbrakes on the bike…don’t get it…

I never had a problem with breaking performance nor with carbon…so I definitely won’t jump the disc train (besides on my crossbike, but this is a different story)…
- Philipp Forstner
  
  but I am sure a lot of people, who just got one bike and who about to buy a new bike, will be changing to disc wheels, because every shop gonna try to sell the discs versions…
- Marcel
  
  We also need to consider MTBs ride in groups, with discs, on all sorts of terrain with all sorts of differences in braking speeds and distances + add in sliding, skidding and slipping.
  
  Why can’t skilled road riders do it ?
  
  Of course we can !
  - Philipp Forstner
    
    with MTB if you really brake you gonna skid and the speeds are different, this is something totally different than going down a mountain 60-80kph and and than breaking on a solid surface like concrete. also not fan of the disc-rotors in crashes…
- Steve Brindle
  
  As a mountain biker with no road experience (so take this with a grain of salt), I think the weight is not an issue. The rotor (the only new rotating mass) is close to the axle, which isn’t as critical for acceleration as it would be if that weight was at the rim. Rims will be made lighter (better acceleration) and more appropriate for the aero and tyre demands. Say goodbye to your nice radially laced front wheels though. 2x or 3x cross lacing (on the rotor side at least) will be required to eliminate wind-up as the hub tries to decelerate quicker than the tyre can.
  
  As for different braking speeds for rim/disc and the effect in the peloton, the person on the stronger brakes will still be able to avoid someone braking earlier on rim brakes because they have the stronger system and can still see the person in front. If a person on rim brakes following a person on disc brakes runs into the back of them, then they have probably out-braked themselves for the corner anyway. If someone wishes to outbrake someone else into a corner, then they need to choose a clear line anyway, a no-brainer.
  
  Frames and forks will be engineered to be stronger where required with little weight penalty. Hub strength is not a concern.
  
  As for cuts from rotors in crashes, simply engineering rotors with rounded outer edges (most are like this now anyway) helps reduce the already remotely slim chance of injury.
  
  I suspect though that some of the more fashion conscious roadies will never get over the look.
  - jules
    
    the issue of wind-up is interesting. i would have thought that the objective of fitting disc brakes to roadies is not to access more braking power, but more controllable and reliable braking. the outright braking power can be moderated through careful selection of rotor size and master cylinder bore diameter/lever ratio.
    - Steve Brindle
      
      The wind-up issue is why you never see full radial laced wheels on mountain bikes. Some high end wheels have radial lacing on the non disc side of the hub.
      - jules
        
        my question is that if you can tolerate reduced outright braking power on roadies, would wind-up still be an issue on radially spoked wheels?
        
        Steve Brindle
        
        Not sure why there would be a requirement for reduced braking power. Seems to me, if you’ve got the grip on the road and the braking power to stop quicker, you (especially in a racing situation) will always want to maximise that.
        
        And the wind-up would always be an issue with radial because the opposing forces between the hub and the tyre have to be transmitted somewhere. The spokes hold it all together, and cross laced spokes leave the hub at a tangent (the resulting force on the spoke is a pulling one, nearly parallel to the spoke and inline with the nipple/rim/spoke interface) whereas radial spokes leave the hub at 90 degrees and the force is tangential to the nipple/rim/spoke interface. There’s way more to it than this, but I hope you get the idea.
        
        It’s why rear wheels are always cross laced, because there’s torque applied at the hub.
- sam
  
  You bring up a great point about the strength of carbon forks that everybody else has failed to mention.
  
  If a steel touring bike fork can snap under disc brake forces how are carbon forks going to go stopping a bigger rider from 90k + in a very quick amount of time.
  
  I think it is absolutely essential that frames are structurally redesigned for disc brakes. If manufacturers are just simply patching on carbon to an existing fork then we could see lots of high speed face plants…
NathanMerckx

Question: If I rock up at my local B grade ride with disc brakes, will I be allowed to race?
- http://www.cyclingTipsBlog.com cyclingTips
  
  No, not if it’s sanctioned by your state cycling federation.
- http://www.cyclingTipsBlog.com cyclingTips
  
  No, not if it’s sanctioned by your state cycling federation.
http://www.facebook.com/pmark1bike pmark1bike

Brakes only work as well as the grip between the tyres and road, once they lock up on a road fun is over, how many times in a race does one guy come off and the others following touch their brakes and go out in sympathy, it will this be worse with brakes that work better. Still a work in progress I feel.
- Dave
  
  The problem is that on a long twisty descent, cable-operated rim brakes aren’t allowed to work even as well as the tyre/road interface for a sustained amount of time. You get brake fade after a few hard corners in a row, run the risk of destroying the wheel/tyre interface, and they don’t work in wet weather.
- velocite
  
  I think I disagree with this. When you can go from a slight deceleration to lock-up with one finger you have a much better chance of modulating braking after an incipient skid.
Beautiful Bike

I like the idea of disc brakes and modulation benefits BUT
quit with the “Carbon Clincher” braking issue. It’s a joke b/c you see Zipp, Easton, Enve all talking about their designs,R&D and how prudent their testing is. Go to their websites! C’mon man. So these carbon wheel companies are going to say they were wrong all along?- “but here, buy this because blah blah blah.”

The real issues no one is talking about:
1)chain stay lengths and FD/RD shifting compromises in regards to height placement of FD plus chain alignment to chainrings and cassette.

2) Fork/Head tube safety.
a) wear and tear
b) brake chatter

It’s been two years and all the same people are using the same talking points? So nothing has changed developmentally?

IMHO
It’s weaksauce to “fear” people into buying security.

BTW,
If 29ers are so awesome, why is the industry bringing up 650 as the best of both worlds(26 vs 29)? Interesting how it all works, ya think they would have offered 650 first. Whatever, Eff me w/ disc, it doesn’t hurt anymore.
RayG

Get off of my lawn!
ultra

everybody banging on about disc or rim brake,the same thing happens when you apply to much braking force to a tyre pumped to 9 -10 bar in the dry or wet you skid, the thought of hundreds of sportive riders being able to apply more braking force in the wet is frightening !
marsci

Not sure yet about disc brakes on a roadie, yes they will grab better, but the contact patch of the tyre on a roadie is much smaller than that on an MTB so this could be a recipe for disaster, at least in the short term. How many riders that can’t brake for shit on their MTBs ripping up trails by losing traction through skidding or dragging their brakes, so transition that behaviour onto a roadie and when the disc brake bites they will lose their rear. That said, learning how to brake coupled with managing the power put into the brake should help. Will it happen, yes, do I think we really need it, not sold just yet.
MadBlack

Bring on the discs and forget about the backwards UCI! I’ve taken the liberty to rebut Mr. Johan Backwards in the following:

• higher speed
MTB’s consistently get up to 80 - 90km/h. The very few races on the road where one might get 10 or 15km/h more won’t be an issue because it’s well within the safety in design.
• longer braking time
I have never seen anyone riding downhill constantly engaging the brake. Plus higher wind speed = enhanced heat dissipation. There are MTB downhills of comparable length to the descents in the alps or Pyrenees all of which are mastered by current MTB disc brake systems without any issues!
• higher temperature accumulation
see above. No an issue on any current MTB disc brake design. There are cooling fins on the brake pads as well as on disc. Also designs allow for fluid expansion.
• bigger disk which means bigger safety issue in case of crashes
I would argue that we’re talking about small discs for road use (140 or 160mm) compared to downhill MTB (>200mm).
• braking behaviour that may block the wheel and make the bike slip
I’d argue the opposite here. Once a rider is accustomed to the brake’s performance there’s no reason to assume that a wheel would be blocked. In fact the contrary is the case the superior modulation of the discs will prevent a wheel from blocking.
• difference of braking performance between disc brakes and rim brakes that may cause crashes inside the peloton.”
Well, he does have a point here but this one is the only one that actually REQUIRES rectifying. Come on UCI please legalize the braking revolution!

In closing I’d go as far as to say that Uran wouldn’t have crashed on Sunday if his bike was disc equipped.
- Dave
  
  That one point that does need rectifying would be easy to deal with - demerit points on riders’ licenses for causing crashes. Cause too many and you sit on the sidelines for the next race you get selected for and the team goes one rider short.
JWLane

The aero issue is a designer chore someone will take care of in an admirable way, eventually. Most of the concern is about near term implementation, or ‘it looks funny’. Most people will migrate when it’s right for them. Having to wait for heat to dry your rims in a down pour - sucks. Bikes are a beautiful, evolving art form, and one day ‘your’ issue will be addressed.
bbbici

I have been racing for 25 years, and I can expertly say that in road racing I barely even use the brakes let alone need stronger ones, and certainly rim brakes are strong enough to exceed the traction of the small tire contact patch and low momentum of lightweight wheels. However, for cyclocross where you have frequent aggressive braking, a much larger tire contact patch, and consistently dirty/wet rims, disc brakes are a great idea.

The aesthetics of road discs will certainly be improved and I am sure we will see some smooth aero calipers in the next few years. Discs are also quite ugly, but easily made prettier.

As someone who has cut his finger on a disc while servicing his mtb, safety is definitely a concern for road racing. However, all that needs doing is the discs having radiused edges rather than simply stamped from a sheet and left with razor sharp edges.
Ian TheMusette Walton

Glad to say I have mechanical shifters and I don’t have an iPad. I don’t wonder what I do without them, on the contrary, happy to not have either. (but I get your point Wade;-) )
- scottmanning
  
  This! Where is the like button? :-)
  
  My wife has had an iPad since Jan. I’m still trying to come up with a use for it!
Jon Thornton

I had a very scary rear tube blowout earlier this year while descending Baw Baw. Braking heated my rim. The rim heated the air in my tube causing it the air to expand. BANG at 40km/h. Fortunately, I was able to wrestle my bike to a safe stop.

I might have been able to avoid my Baw Baw blowout by lowering my tyre pressure, fitting softer break pads, or just by braking smarter.

I really worry about rim heat on descents like Baw Baw and Mt William above the carpark. Disc brakes would greatly reduce my worry.
- jules
  
  one thing that CT didn’t touch on in his article here is the purported risk of overheating in the form of boiling brake fluid. i recall discussing this here in a previous blog post and was left with the impression that the consequence was just as severe as a blown tube. the question is - is that outcome still a risk? (obviously cables are a solution)
  - http://www.cyclingTipsBlog.com cyclingTips
    
    I’ve never heard of that - even with DH mountainbikes. How does the fluid overheat and boil?
    - jules
      
      good discussion here (read shimano guy’s comments). http://www.bikerumor.com/2013/04/11/tech-speak-brake-fluid-break-down-and-implications-for-road-disc-updated/
      
      essentially he says the pads will fade before boiling becomes a problem, and that the risk is not so much the fluid itself boiling as vapor lock due to vapor ingress (same outcome though), which is eliminated by using mineral oil rather than DOT brake fluid (although my Avid systems all use DOT)..
Ben Shane

In a way, there are three brakes on every bike - two are at the wheels, while the rider’s awareness, skill and instincts form the other brake. If the rider sucks, the other two brakes wont keep him/her safe, regardless of what part of the wheel they grab onto. My prediction is that cx and fondo bikes will go entirely disc and hords of recreational road riders will choose those bikes as their go-to road rig. But seriously, putting disc brakes on a venge, evo, or scott foil just seems silly, so each company will leave at least one “pure” RACE bike in the lineup, for at least another decade. Also, dude from SRAM comparing the application of discs on the road to discs in mtb had me LOL’in.
Dr.Ferrari

I think we should leave it to Cipo to decide….
Mike Hogan

One point not being discussed Is Tire contact patch Dual pivot calipers can already lock up the wheels And tire adhesion will be the limiting factor.
- Rohan
  
  Ding Ding Ding - we have a winner!
Indrek Narusk

It could get tricky when UCI will lower the 6.8kg weight limit, and allow discs… Then you have the option to use discs in a race, but then again you’d want the light bike (5kg) with rim brakes…
RickH

When did cars lose their drum brakes and why?
Several things come to mind with bicycles though.
Weight. Overall there is little extra weight with the high end hydro road brakes from Sram. Less than a quarter bottle of water.
Wheels. I would not like radial lacing of a front wheel with the power of disc braking from the hub.
Aero disadvantage. The human body creates more than 80% of the aero drag on a moving bike and doubles exponentially with the increase of speed. In saying that where less than a second can make the difference in a TT I wouldn’t have discs.
Braking in all kinds of weather. Disc brakes for sure.
Mountain descents. Disc brakes.
Non UCI racing. Disc brakes.