disc brakes for road bikes?

[rinconryder]

http://www.bikerumor.com/2011/05/23/stevens-carbon-disc-brake-cyclocross-bike/

I think it is only a matter of time until they become a regular part of road bikes. Maybe five years? I realize that the stays and forks need to be beefier to support the caliper mounts, but with the advances in carbon and bikes getting so light as is the weight penalty will really be minimal or offset. The rotors would obviously be smaller, maybe 100-120, but it would also alleviate the headaches with carbon wheels - although I think that issue will be solved within the next two to three years.

Maybe I am totally off, but curious to see thoughts on this?

[eddief]

weenies won't buy em...no matter how well they work. unless wet is an issue.

[jpw]

I can imagine that Di2 sti levers are being prototyped with master cylinders under the hoods for hydraulic disc braking. In the absence of mechanical gear changing components a lot of space becomes available in the space for braking innovation. Now that the UCI, that august body of unimpeachable reputation, has changed the CX braking rules expect new products to show up at the end of this summer season.

[cmg]

if this happens, then rims could get lighter both in aluminum and carbon, which would be the driving force. the only thing that would wear out the rim would be when you rolled over a rock and damaged the surface.

[sbparker31]

Disk brakes work well in the mountain bike set because of smaller (26") wheels with shorter spokes and beefier wheel builds. When the braking occurs at the hub, all the forces have to travel through the spokes to the rim to the contact patch. That said, braking power depends on the stiffness/strength of the overall wheel, which is not a problem with the stouter wheel.

Taller wheels present a problem (700c, 29er wheels) with disk brakes. This has already been observed with the trend to 29ers in Mountain bikes. 29er wheels have to be built up pretty strong and stiff (read: more spokes) to work well with disk brakes, or strange things begin to happen -- I've heard people say they can feel the wheel flexing and hear spokes making popping sounds on hard braking.

If you translate to the 700c road bike realm, I'm sure that lightweight, low spoke count wheels that are so popular now won't be able to handle the braking forces.

If you think about it, a wheel with a rim brake serves as one giant rotor -- think 160mm rotor vs. 700mm rotor. 29er wheels with rim brakes actually have much stronger braking than 29er wheels with disk brakes, without the stress on the spokes/hub.

Rim brakes on road bike wheels already provide a very efficient braking design, particularly with modern dual pivot brakes, newer brake pad compounds and aluminum brake tracks. Also much lighter than disk brake setups, easier to adjust, etc. Anything else is probably a step backward.

[Mark McM]

if this happens, then rims could get lighter both in aluminum and carbon, which would be the driving force. the only thing that would wear out the rim would be when you rolled over a rock and damaged the surface.

The 'lighter rims for disc brakes' claim has been around since disc brakes started becoming popular for MTBs, yet the weight savings has never materialized. The extra material added for brake tracks on rims weighs a few dozen grams at most, and quickly gets overcome by the flange material required to mount a disc to the hub. If you compare disc brake specific wheels to rim brake specific wheels, the disc brake specific wheels are already heavier even before you add the disc and caliper.

[Sheldon4209]

The Avid mechanical disc brake has become popular on tandems. It stops faster than other brakes, works when wet, and does not build up heat in the rims to blow a tire. Spoke breakage does not seem to increase with the disc brake even when used with wheels with low spoke count. If a bike is used in conditions such as higher weight, rain, steep hills, or any combination I could see their value.

[xjoex]

I have a disc brake equipped cross bike. Its great, I'll never go back to canti brakes. They just work so well.

If you live in a really wet area I could see them catching on for road bikes.

-Joe

[cmg]

The 'lighter rims for disc brakes' claim has been around since disc brakes started becoming popular for MTBs, yet the weight savings has never materialized. The extra material added for brake tracks on rims weighs a few dozen grams at most, and quickly gets overcome by the flange material required to mount a disc to the hub. If you compare disc brake specific wheels to rim brake specific wheels, the disc brake specific wheels are already heavier even before you add the disc and caliper.


heavier overall. i was just talking about decreasing the weight of the rim as a result of not having the rim brake wear, but as stated by sbparker31's post the rim thickness may have to increase.

[AngryScientist]

don't need 'em, dont want 'em.

[the ill postino]

On the weight question, I was interested to see that the new disc brake Gunnar Hyper X (cross bike with road geo) uses lighter tubing than the canti brake Cross Hairs because, they say, brake chatter isn't an issue. The stays and dropouts are heavier for the disc brakes, but there is still some weight savings on the frame. My guess, though, is that the weight of the disc brakes themselves then neutralize those weight savings.

(FWIW, I have a canti brake cross/road bike, disc brake mountain bike, and caliper brake folding bike, and can't say I have any complaints with any of them.)

[mjb266]

The 'lighter rims for disc brakes' claim has been around since disc brakes started becoming popular for MTBs, yet the weight savings has never materialized. The extra material added for brake tracks on rims weighs a few dozen grams at most, and quickly gets overcome by the flange material required to mount a disc to the hub. If you compare disc brake specific wheels to rim brake specific wheels, the disc brake specific wheels are already heavier even before you add the disc and caliper.

I'm thinking that the Stan's line of rims are the first to really go after the weight savings that are possible with disc brakes. A pair of ZTR crest rims in the 29" size are under 400 grams with the 26" rims under 350 grams. They are pretty durable to boot. Add to that the weight reductions way out on the rim versus the weight penalty for a disc mount and the moment of inertia is significantly reduced.

I'm not saying that they have the best system figured out yet for discs, but it will get there. To date, cost and braking have been the acheilles heel of carbon wheelsets. A disc rotor would allow one of those drawbacks to be addressed.

[jmason6]

I have had no problems with my niner and disc brakes. No flexing, that being said would have to agreed with those above unless water is an issue would prefer rim brake over disc for road. it is just a giant 700mm rotor. Thankfully in FL don't need to use brakes much, flat road and most of the roadies just run the lights. Hence all of those hit by cars.

[torquer]

... but it would also alleviate the headaches with carbon wheels - although I think that issue will be solved within the next two to three years.
One headache would be the reputed heating problem with all-carbon clinchers. That issue didn't get discussed much in recent reviews of carbon clinchers that I've read, though, so I don't know if that means rim makers have solved it, or the reviewers accepted it as an inherent limitation. FWIW, the manufacturers' previous common work-around, aluminum braking tracks, seems to be on the decline, so maybe this headache is going away without discs.

[RPS]

The Avid mechanical disc brake has become popular on tandems. It stops faster than other brakes, works when wet, and does not build up heat in the rims to blow a tire. Spoke breakage does not seem to increase with the disc brake even when used with wheels with low spoke count. If a bike is used in conditions such as higher weight, rain, steep hills, or any combination I could see their value.
A disc (or two) can eliminate or replace other types of drag brakes used on tandems which can therefore reduce overall weight. On single bikes which don't normally have overheating problems and therefore don't require drag brakes this benefit isn't as much of an advantage; if at all. Old drum drag brakes used on tandems were quite heavy.

[RPS]

...snipped.....
If you think about it, a wheel with a rim brake serves as one giant rotor -- think 160mm rotor vs. 700mm rotor.
....snipped.....
+1

Also, at the front a disc introduces asymmetrical spoke tension which must add some additional weight. It’s probably minor, but must be there. Another concern of mine is greater asymetrical flex in one fork blade which may affect steering under hard braking. Also minor, but it's got to be there.

[jblande]

the cases in which i would consider disc brakes on a road bike are also ones in which i would not consider greater weight a penalty

[benb]

They can make it work and I'll be all for it.. consistent braking, improved braking performance, and maintenance periods measured in years instead of weeks or months are all benefits as far as I'm concerned..

The amount of time I spend cleaning, maintaining, adjusting, and replacing brake pads & calipers on my road bike compared to my disc equipped mountain bike is just ridiculous, and the mountain bike is the one that gets used in bad weather and gets abused. I'm fine with the rim brakes when they are brand new, the rims are spotlessly cleaned, the brakes are perfectly adjusted, and the weather is good. But that never lasts long.. the disc brakes are just perfect every time, and I'm totally confident I can descend any road in the US in any weather even if one of the brakes fails completely and be perfectly safe.

This would be an example of real innovation.. not going to cry about a few grams if that's what it takes. I find rim brakes to be the highest maintenance item on my bikes..

[Mark McM]

the cases in which i would consider disc brakes on a road bike are also ones in which i would not consider greater weight a penalty

But can't that be an assymmetrical equation? Sure, there may be greater advantages than disadvantages to disc brakes when coming down a steep technical descent; but descents don't usually exist in isolation, you usually have to climb the other side first, where (at least in competition) disc brakes may have greater disadvantages than advantages. In races, you can usually lose more time on a climb than you can gain on a descent, so I don't see disc brakes taking over the pro peleton anytime soon.

(Of course, outside of racing, the advantage/disadvantage equation can be quite different.)

[flydhest]

weenies won't buy em...no matter how well they work.

I somewhat disagree. Integrated shift levers took over and they weigh more than DT levers and simple brake levers. Weenies have embraced them (if not always at the vanguard).

[eddief]

and it seems as if integrated brake/shift levers represented a pretty radical and (for me) much more significant change from what came before...as compared with the differences in braking that would come with discs over rim brakes. i'm open and loved the disc brakes on my recumbents, just not enough to embrace them for my mostly fair weather riding on diamond framed road bikes.

I somewhat disagree. Integrated shift levers took over and they weigh more than DT levers and simple brake levers. Weenies have embraced them (if not always at the vanguard).

[that guy]

New technologies don't replace current ones, they only supplement them. Sometimes they overshadow them, but they never replace them (http://www.npr.org/blogs/krulwich/2011/02/04/133188723/tools-never-die-waddaya-mean-never) .

There will always be rim brakes, but make no mistake, there are a LOT of disc-brake equipped road and 'cross bikes headed our way. As the market expands, product innovation will accelerate until the weight and performance issues are insignificant.

[oldpotatoe]

New technologies don't replace current ones, they only supplement them. Sometimes they overshadow them, but they never replace them (http://www.npr.org/blogs/krulwich/2011/02/04/133188723/tools-never-die-waddaya-mean-never) .

There will always be rim brakes, but make no mistake, there are a LOT of disc-brake equipped road and 'cross bikes headed our way. As the market expands, product innovation will accelerate until the weight and performance issues are insignificant.

Cross, you bet, MTB? absolutely, touring? great idea but on you basic 16-17 pound road machine fashioned after the rigs raced in Europe...I don't see it anytime soon.

Frame and fork makers have to embrace it(and before you mention BB30, etc, that frame is cheaper to make, not more expensive) and making a frame and fork handle disc brakes is going to cost them more, not less. Same for hub makers and lever makers.

Somebody mentioned stuffing a disc brake reservoir in a Di2 lever, maybe but into a lever with shift guts..gonna have to be external and at least today, those aren't pretty.

Same thing was said about another MTB technology that morphed into road bikes and many said, tubeless road is gonna be everywhere, but 10 years on, one tire maker, a handfull of wheel makers.

It answers no big question, solves no big problem. Marketeers will embrace it, but that's all...IMHO.

[Bob Loblaw]

It's been alluded to before, but to accomdate a disc brake, a wheel has to be different (heavier) in some key ways.

First to go is radial lacing and low spoke count. Cross-lacing is necessary to handle the torsional loads associated with disc brakes, and I am pretty sure 20 or 24 spokes wouldn't be enough to handle the torque generated by braking loads on a long, technical descent.

Rims would have to be stronger around the spoke holes, which would mean more weight. Rim brake wheels only have to handle as much torque as a person can dish out, and that only at the rear. Disc brakes generate much higher torque than that at both the front and rear, and on a standard rim, I'd predict cracked rims and spokes pulling right out of the holes.

Then there's the aerodynamic disadvantage. In addition to losing radial lacing, you'd have a disc and disc hub out in the breeze, plus the caliper and associated bolts and mounting hardware.

On the flipside, the only real advantage I can see would be in wet weather performance.

I admit to a tendency towards retro-grouchiness, but I think rim brakes are generally so good, disc brakes are pretty much a solution without a problem. In the pro peloton, you might eventually see them on special spring classics bikes, but IMO, that would pretty much be the extent of it.

BL

[zap]

A disc (or two) can eliminate or replace other types of drag brakes used on tandems which can therefore reduce overall weight. On single bikes which don't normally have overheating problems and therefore don't require drag brakes this benefit isn't as much of an advantage; if at all. Old drum drag brakes used on tandems were quite heavy.

Disc brakes should not be used to replace drum drag brakes. The Avids BB7 for example are designed to be used as normal brakes, not constantly "drag-ing".

Rolf offers a tandem disc wheelset with not a whole lot of spokes and appear to hold up well.

http://www.rolfprima.com/products-TandemDisc.php

[RPS]

Disc brakes should not be used to replace drum drag brakes. The Avids BB7 for example are designed to be used as normal brakes, not constantly "drag-ing".

Rolf offers a tandem disc wheelset with not a whole lot of spokes and appear to hold up well.

http://www.rolfprima.com/products-TandemDisc.php
If not disc then what? :confused: Just don't use a tiny disc meant for a single bike which has little braking needs at the rear.

I haven't seen a modern tandem with an Arai drum brake in many years. Granted discs can overheat when undersized, but drum brakes could get hot too. Originally small discs overheated and warped, but that's been corrected as far as I know. The Santana WEB page shows a 10-inch rear disc option which can be added as stand alone or used at rear with DA front caliper on high-performance road tandems.

[jpw]

A wet Paris Roubaix (i.e. a mud bath) will be the perfect cross bike/ disc brake marketing debut. There hasn't been one for years. I vote to push it back to March, but after Milan San Remo :-)

Expect disc brake innovations to start popping up in three months to three years. As soon as Di2 gets the mud treatment I'm buying.

[d_douglas]

I don't race, so I cannot comment on the relative advantages.

BUT from my own perspective, I welcome the innovation. I have discs on my Redline and they are awesome in bad weather and on a trail.-

Yes, once Shimano goes hydraulic, I will convert fr Campy. Even better, let's see Campy make a hydraulic system!

[jamesutiopia]

If the cable and hydro products we have today are all that will be available then clearly disc brakes will not be a viable choice for the road and a less-than-compelling choice for cross. I don't doubt the ability of the major component makers to get the weight (to UCI minimum) and modulation under control through product development and look forward to seeing if they can make discs a compelling proposition.

If a yet-to-be-revealed disc brake can be shown to have better power and modulation than a rim brake and coupled with Di2-style electronic shifting I can see how these features could drive an entire sales cycle of new frames, forks, and wheels in 2012 and beyond...

Can't say I am chomping at the bit for this, but we'll see what they come up with

[zap]

If not disc then what? :confused: Just don't use a tiny disc meant for a single bike which has little braking needs at the rear.

I haven't seen a modern tandem with an Arai drum brake in many years. Granted discs can overheat when undersized, but drum brakes could get hot too. Originally small discs overheated and warped, but that's been corrected as far as I know. The Santana WEB page shows a 10-inch rear disc option which can be added as stand alone or used at rear with DA front caliper on high-performance road tandems.

Let me start right off and state that whatever Santana say's or writes about or posts is not relevant. Too much nonsense and poor product selection that no one with any serious tandeming in mind would consider any of it, atmo.

Tandems typically use 203mm discs. One of our tandems has such a disc (rear) and am ready to add front disc as well.

The real issue are brake pads. Just like in an automobile, pads are designed for harder efforts. Drag a disc and the pads will become useless when you realy need it.

But really, with discs who needs a drag brake. Ride the tandem like you would a single, just faster;)

[RPS]

Let me start right off and state that whatever Santana say's or writes about or posts is not relevant. Too much nonsense and poor product selection that no one with any serious tandeming in mind would consider any of it, atmo.

Tandems typically use 203mm discs. One of our tandems has such a disc (rear) and am ready to add front disc as well.

The real issue are brake pads. Just like in an automobile, pads are designed for harder efforts. Drag a disc and the pads will become useless when you realy need it.

But really, with discs who needs a drag brake. Ride the tandem like you would a single, just faster;)
Agree on both counts. Santana oversizes things like steerers and rear wheel spacing to a degree that makes little sense to me -- unless you have very specific heavy-duty needs like triples or quads, or super loaded touring.

At a combined weight of 250 to 260 pounds, Nancy and I mostly ride a Co-Motion with standard Ultegra road calipers and that's plenty for us -- no drag brake at all. I feel I can stop just as fast as with my single since the rear brake can actually contribute to panic stops. My Cannondale is set up for an Arai drum but I never installed one for the same reason. If I rode mountains out west I'd probably want one, but thus far never had the need.

At our weight I have mixed feelings about discs even for a tandem. If I were buying a new tandem today I'd stick with road calipers although I'd have provisions for a future rear disc. just in case.

[FlashUNC]

Its a solution looking for a problem on your standard road bike, I think.

For cross and other applications, I think it definitely makes sense. But your usual Saturday morning hammer fest? Dunno why anyone would want them.

[Seott-e]

I wouldn't be without them on my mtn bike, but on a road bike I just don't see the need.....

[T-Crush]

For me, it's not a case of need (I don't race so I clearly don't need Record, or a 14 pound bike, etc.), it's a case of lust. I just think it looks incredibly trick.

[Volant]

I wouldn't be without them on my mtn bike, but on a road bike I just don't see the need.....

Unless you're in my neck of the woods and have 7 mile descents at 6% grade and you ride in the early a.m. when the mist is still hovering which means your rims are wet all the freakin' time. Then they make perfect sense on a road bike.

[Germany_chris]

I'd put them on any bike, disc's are just that much better.

[bicycletricycle]

does anybody here feel like their modern road calipers don't stop well enough?

most product developments do not come around to address needs these days so it is not a requirement for there to be a problem for someone to try and fix it but i am still curious.

[oldpotatoe]

does anybody here feel like their modern road calipers don't stop well enough?

most product developments do not come around to address needs these days so it is not a requirement for there to be a problem for someone to try and fix it but i am still curious.

Geeezz, I use Deltas and they stop just fine and dandy. Modern DP calipers do too, better. For commuters, tourers, where you ride in the wet and crappy, tandems(heavy), MTBs, places where you would wack a rim..all great applications for discs but on your group ride, enthusiast bicycle, don't see the need. BUT some will get them just cuz it's new and whizbang.

[bicycletricycle]

i kinda feel like modern dual pivots are more than enough power, expecially shimano. carbon rims and rain would be a couple good arguments i guess.

[A1CKot]

i kinda feel like modern dual pivots are more than enough power, expecially shimano. carbon rims and rain would be a couple good arguments i guess.

I wonder what carbon rims would look like if they didn't have to work around a brake surface. I feel like the rims would be lighter and stronger and possible cheaper.

[jpw]

does anybody here feel like their modern road calipers don't stop well enough?

most product developments do not come around to address needs these days so it is not a requirement for there to be a problem for someone to try and fix it but i am still curious.

Yes, when it's raining they're crap. :D