[Closed] Why dont road bikes have disc brakes????

Because designing the forks to cope with the additional strains and stresses is quite tricky.

Arguably they are overkill - v-brakes do a perfectly good job.

The roadie market is pretty conservative (apart maybe from carbon fibre).

Tyre contact patch is tiny - I can comfortably lock the wheels using my Ultegra brakes, and they modultae just fine. Why would I want to add more weight for unnecessary levels of braking?

That's why!

Because they don't need them.

As above......
My road bike is a MTB h/tail with slicks,rigid forks & disc brakes.First time out in the wet was very interesting 😕

Some do

[img] [/img]

Well I would like to have some disc brakes that work well despite the weather as a road bike can be really quick and get quite scary sometimes.

But like Ourmaninthenorth mentioned try to get some proper braking without locking the wheels when Your tires are 23mm wide and pumped up to 120psi. Just too much in my opinion.

My 105 brakes were just fine with shaving off speed but current Tektro Oryx work better when it rains/snows 🙂

But thing is, Druidh Your bike has drop bars, but is that Kona a proper road frame or a CX frame? XT on rear as well. Just some roadies would not qualify it as a 100% road bike.

But if I had a bike like a tourer/commuter with ability to put panniers wider tyres, than to stop all the extra weight I think I would like to have discs as well.

Yeah that's not a road bike, there's no point at all in discs on a true road bike. On touring bikes they make sense. They would add a lot of weight and probably make the bike less controllable.

mieszko - Member
But thing is, Druidh Your bike has drop bars, but is that Kona a proper road frame or a CX frame? XT on rear as well. Just some roadies would not qualify it as a 100% road bike.

But if I had a bike like a tourer/commuter with ability to put panniers wider tyres, than to stop all the extra weight I think I would like to have discs as well.

It also has a triple chainset - to most roadies, that's also against the rules 🙂 But your thinking is the same as mine - added weight deserves better breaking. And for those that want to start on about "lack of modulation" / "disk brakes locking up too easily", then I'd just suggest you're a bit ham-fisted. You need the hands of a lover, not a fighter.

Because the bike would be significantly heavier to allow for the additional loads that disc brakes put forks and frames under in places that they currently don't have. Also hubs, wheels and brakes would be heavier as well.
Maybe, when a disc brake equiped bike can be produced under 15lb in weight then you'll start to see them be used, until then.

The brakes on my road bike work fine so I couldn't see any need for fitting discs and to be honset it would be too much braking. Also in general you can see whats up ahead much better than you can on an mtb so there isn't the need for last minute braking.

I'll be fitting a front disc to my cx commuter though but its got 32mm slicks and I ride it a lot in the rain.

Put discs on this..

[url= ]Nice road bike[/url]

And I for one would give you a good shoeing.

😉

God! It looks like the cat threw up over that bike. Ugly isn't the word.

why don't road (racing) bikes have discs? most importantly, the UCI rulebook I'd guess

I reckon someone could produce a disc-braked bike that was at the weight limit if they were allowed, though I doubt there'd be much advantage in braking performance - I certainly think you would need the hands of a druidh if you were using discs on a high speed alpine road descent in the wet. Also, if it was dry I wonder how badly a minimalist disc set up might overheat (then again, I don';t do this riding so I don't know how badly conventional brakes suffer either)

Conventional brakes can get very hot, hot enough to melt tubular glue and roll tubs off the rim, or cause blowouts in clinchers. Like MTBing though, if you brakes properly you'll be fine, if you drag the brakes the whole time, you won't be!

How many more times do we have to see that picture druidh? I wish I had a quid for everytime I had seen it, could probably afford to buy you a proper road bike with the proceeds 😉

Disc brakes would be a welcome addition to my touring tandom; it's a nightmare to stop on steep/wet descents with a lot of luggage on the back (no not you dear - panniers I mean)

Basically because it's lethal. I put 25mm tyres on my 29er with discs to commute and the power overwhelms the contact patch on anything other than dry, smooth roads. Don't do it, no point.

Mister P - Member
How many more times do we have to see that picture druidh? I wish I had a quid for everytime I had seen it, could probably afford to buy you a proper road bike with the proceeds

I have others. . . .

[img] [/img]

It's not really about UCI rules, or weight, or the conservatism of roadies. they simply don't need them. I doubt any roadie coming down a 20 mile alpine descent would ride any quicker with discs. they often accidentally lock up with rim brakes. discs would just be too much braking power for the available tyre-ground grip.

if you have normal road brakes and they're not enough, try cleaning/scouring the braking surfaces or maybe switching to some better pads.

tourers and tandems are a different matter though - fatter tyres with bigger contact patch, bike weight less important but load weight much higher.

they often accidentally lock up with rim brakes

what, the front ?!!!!!!

I don't think many people would suggest discs purely for absolute power - other than in wet or clag, either of which would potentially make road descents dangerous with discs as I suggested above. Think it's more to do with consistency, self-adjustment (could you wear out a set of blocks so as to affect lever function on a single mountain stage, for example ?) and, if done well, resistance to overheating

it's very easy to throw yourself over the bars with good road brakes (i use dura-ace) and the back can be locked up easily. if you run fat tyres 38c + then maybe disks would be useful but for ordinary road bikes they are not needed.

i can't see a set of pads being worn out enough on a mountain road descent to affect braking, i'm still on a set of pads that have lasted a year and 6000+ miles.
some tandems do have a disk 'drag brake' for speed moderation on long downhills
or a drum based one
[img] [/img]

6000 miles on a set of blocks - blimey, might cut some down & superglue onto my worn disc pads (if only someone would make disc pads where the material could easily be removed from the backing...)

I reckon the over the bars tendency is quite strongly linked to position too though - arse high, hands low etc. Maybe all tour de francers should use discs AND adjustable seatposts

"[i]Maybe all tour de francers should use discs AND adjustable seatposts[/i]"

they don't need to, they know how to ride a bike

🙂

they don't need to, they know how to ride a bike

aye, such is their unmatched skill, I've seen them combine it effortlessly with abseiling, ice skating, skittles, ...

:winkythingy: :bigkiss:

"what, the front ?!!!!!!"

Yes, it happens from time to time. you'll see someone braking hard into a corner and the front wheel just locks and goes from under them.

"Maybe all tour de francers should use discs AND adjustable seatposts "

I'm sure you're right. To be fair to them though, they just use whatever bike they can get their hands on. if only they had bikes designed perfectly for the job at hand...
🙂

you'll see someone braking hard into a corner

now you're just trying to upset JoB, suggesting they don't know how to ride a bike like that

:dontlikethosescaryfaces:

The popular answer seems to be that disc brakes are tod heavy and too powerful for road bikes. So make smaller, lighter less powerful ones for the road that give as much stopping power, still work in the wet and don't wear out your rims. Maybe not for racers where forks may need beefed up and dropouts redesigned.

They are dangerous in a bunch racing situation, there is too much risk of a tyre/ disk contact/ overlap in large racing bunches where the riders are very close..

and they are too much for skinny tyres

good for tandems though

The limit to road bike braking is tyre grip, not brake power. Proper dual pivot rim brakes work well enough and are lighter than discs for reasons others have gone

I've got a CX with disc brakes on and it is great offroad but in the wet with 25mm slicks things can get very spicy very quickly, especially when you add in a bit of road film to make the discs all grabby. It's OK with wider semislicks or proper 'cross tyres though.

Proper road bike with 105 brakes is perfectly adequete, I have ridden it in the Alps on long hairpin descents and been just fine and I'm quite heavy (15st). Can't say I've ever wanted more brakes on it.

[img] [/img]

Uuugh, that's wasn't originally designed to take the Arai was it? You do know your bolt holding the torque arm to the pacman has fallen out don't you? Oh, and who invented a combination ladder/tandem? 😆

Here's a good'un.

6.8kg, with disc brakes.

And three calipers...

[url= http://www.canyon.com/_en/technology/project68.html ]http://www.canyon.com/_en/technology/project68.html[/url]

The spoke/rim loading is also reduced, as the spokes on both sides of the wheel only have to carry half of the braking force.

I have not had particularly good experiences with disc brakes on my mountain bikes, and am not a convert particularly. My road bike's brakes work absolutely fine. In the sense that they do not require any attention at all and work well all the time (braking distances may be increased on very wet roads, but you knew that anyway, right?).

Obviously when someone produces super-light disc brakes allowing for lighter rims saving rotating weight blah blah blah so that they are widely taken up at the top of the sport that will all be very positive I'm sure. It is unlikely to make the £1,000 bikes of Sunday club run enthusiasts like me any better or cheaper or better value I suspect.

🙂

"make smaller, lighter less powerful ones for the road that give as much stopping power"

Less powerful but with as much stopping power? Eh?

I think the basic answer is actually "it aint broke..."

But I think there may be advantages.

What about tiny little discs, for road bikes? 100,120 or 140mm? Think of long, steep, alpine descents, in the rain. Plus, you'd be able to produce lighter rims (use of disc brakes has led to lighter rims in MTBs), less rotating weight, therefore greater acceleration and more efficient braking. Then, you could have ultra-light carbon rims.

Makes a lot of sense, to me.

I think it's because roadies are snobby bastards, who wouldn't want to be seen following MTB technology; that's really what it is.

There are already road wheels with carbon rims......

Yes- carbon rims that have to be built tough, to withstand braking forces, and weigh as much as alloy rims. thus negating the benefits of using a lighter material.

No good reason why no road discs, though, is there? Let's be honest.

I'd put discs on my roadie, if the products were available, no question. I don't accept for a second the argument that road bikes don't need them.

Bike design and uptake moves slowly, that's just the way it is. And roadies are conservative types at heart. Until the hardware is available and of a decent spec then it's difficult to make the shift. But it will happen.

"[i]No good reason why no road discs, though, is there? Let's be honest. [/i]"

yes, for all the reasons just given

reggiegasket - Member
I'd put discs on my roadie, if the products were available, no question. I don't accept for a second the argument that road bikes don't need them.

Bike design and uptake moves slowly, that's just the way it is. And roadies are conservative types at heart. Until the hardware is available and of a decent spec then it's difficult to make the shift. But it will happen.

LOL. Remind me again - which discipline of cycle sport banned skinsuits because they didn't fit in with the "image" despite their performance advantage?

As professional road racing is currently a richer sport than mountain-biking, with a substantial global recreational market full of people who are just as susceptible to buying the latest must-have item as the posiest mountain-biker (and indeed many of them are the same people), I rather think it likely that there is no good reason why road discs, actually.

🙂

It's possible to suggest reasons why they might be good, but bottom line is that there is a lively international racing scene performing at a very high level wityhout the assistance of this vital technology. The teams and manufacturers competing have the money and know-how available to use the technology if it would give them an advantage in extremely competitive competitions. I'm sure the UCI currently doesn't allow it, and there may be an element of snobbery there, but I suspect if good designs were being brought forward by the main component makers they wouldn't stand in the way. Afterall, it's a safety thing, and it dfoesn't make the bikes look stupid.

"[i]And roadies are conservative types at heart.[/i]"

no they're not, they'll try anything to gain an advantage, which is why there aren't discs on road bikes

Have you seen how much carbon road forks flex when you hit a bump though? It really is quite surprising if you watch it.

I guess it should be possible to make carbon forks that can take all the extra force on them, but they'd have to be less bendy than existing ones, which are apparently designed to be bendy to reduce the effect of bumps in the road.

On the locking up thing - I locked up the front just after hitting 75km/h once, it skidded a tiny bit, but in a straight line, just like a back tyre skid. That was jolly scary. It was because we were aiming to hit silly speeds down this particular descent where you get up to full speed just before a 120 degree turn, marked for cars as a recommended speed of 20km/h. The later you slow down for the corner the faster you can go, I just left it a bit too late.

Joe

it skidded a tiny bit...I just left it a bit too late

Yeh, that'd be pretty scary
I revise my previous suggestion:

... discs, adjustable seatposts and ABS

and armour, maybe

I assume that this means that my out of date, heavy, uncompetitive 12/ 20 spoke carbon wheelset will be made even lighter than the 960 grams that they weigh currently with the introduction of lightweight disc specific rims?

you guys are mixing up road riding with racing

just cos the racers don't want/need it doesn't mean regular road riders are the same.

take compact cranks. Racers didn't use them so nobody else did, and five years ago you couldn't even buy a road compact. Times change. Regular riders started to realise that 39/53 was too high for them so started a shift towards smaller rings. Now you can get the new Dura Ace in 34/50.

Same thing with discs. I don't care what the racers run. I don't race. The 'sport' is irrelevant. I value good brakes, simple as that. And discs are better than DPs, in lots of ways.

reggie - you're confusing riding on the road with riding on a road bike. The latter is done largely for sporting reasons - if not racing then fast training in groups, or sportives - and a lot of the people buying those bikes want their bikes to look the same as the pros. Also for those purposes there really aren't any advantages to disc brakes (compact chainsets are a totally different issue, and have also been used by pros in mountain stages). Maybe you should enumerate some of the "lots" of ways discs are better in the context of road bikes.

** cough **
I've been using road compact since 1996, and so has my SO. All of my road bikes have compact gearing, and the same with my SO. That'd be 6 bikes then 3 of which date back to the 20th century.
I don't road race, and I value good braking, but I find that DP/SP (Italian you see) brakes work pretty damn well. I can't imagine riding the routes I've done in the Pyrenees or Alps with a road bike with disc brakes, certainly not with the technology available at the moment.

I think it's because roadies are snobby bastards, who wouldn't want to be seen following MTB technology; that's really what it is.

Good one that. Most unfriendly cyclists I have met have always been on mountain bikes.

Ever wondered why the MTBers you meet on the trails never look you in the eye? It's because they're checking out whether you've got brakes they approve of....

I think reggie makes a fair point, and is right about compacts, but I'm not sure the logic applies to brakes. Compacts allow weaker amateur riders to get up big hills easily with their spindly little legs. Disc brakes appear to be overkill given the limitations of traction for professional racers descending the highest passes in Europe at absurdly high speeds on closed roads. It is not clear to whom they offer an advantage therefore.

🙂

The latter is done largely for sporting reasons

it's not confusion aracer, it's just an assumption. I am assuming that most road riders are not racers, just regular riders. I may be wrong of course but of all the road riders I know the majority don't race.

That's not to say they don't want to look like the pros though! 😯

In the club I sometimes ride with there are plenty of 'professional' jerseys being worn but only a handful actually compete.

I think for racers the addition of discs is marginal, as weight will be a big issue. But for me, I'd give up, say 200g, to have better braking.

[i]yes, for all the reasons just given[/i]

Which were?

'Too powerful' - use smaller diameter discs, reducing the power compared to a MTB disc.
'Lock the wheels' - all brakes will, if applied strongly enough. Relatively easy to design more modulation into the lever.

So, the advantages (again):

Less material at rim = lower mass = less rotating weight = greater acceleration + increased braking efficiency.
Better in foul wet weather.
Rim brakes rely on very true rims, to be fully efficient. Discs do away with this issue. Dent a rim/snap a spoke on a 100 mile ride, no worries.

You could probably design little discs and caliper systems that would weigh as much, if not less, than rim brakes. imagine; really cute little mini caliper systems. Maybe even little carbon caliper housings! More bling! You could even house the caliper in the fork leg!!!!

See? Makes perfect sense, and youse all know it.

Any manufacturers out there; this is my concept, so don't nick it, or I will want loads of money.

Happy happy joy joy! [img] [/img]

Have you looked at a modern road frame recently? Do you really think any of them will run with a rim which is more than about 1-2mm out of true? I can't think of any time that I've managed to significantly damage a road wheel sufficiently for it not to be rideable - I'm still riding a 10 year old Campag Electron climb-dynamic wheelset that has had one problem and that was due to me sticking a metal sign into the spokes by accident - its still true to within 1mm after 10 years and over 25,000 miles of riding.
Oh, and you'll also need to redesign the forks and frames to take disc brakes.

Oh, and are there any 12 spoke disc wheelsets out there?
Didn't think so.

"[i]'Lock the wheels' - all brakes will, if applied strongly enough.[/i]"

exactly

"[i]Less material at rim = lower mass = less rotating weight = greater acceleration + increased braking efficiency.[/i]"

more material in hub and frame to deal with the different forces disc-brakes exert = greater mass = more weight to drag along = slower everything

"[i]Rim brakes rely on very true rims, to be fully efficient. Discs do away with this issue. Dent a rim/snap a spoke on a 100 mile ride, no worries.[/i]"

in over 20 years of road riding i've had precicely one snapped spoke meaning i merely undid the brakes a bit, this isn't really an issue

"[i]Makes perfect sense, and youse all know it.[/i]"

if it made sense it would already be done, the technology is out there, it just isn't necessary

you sound like you've already made up your mind and are merely being confused by the facts

(knowing wink)

Can't see why not. Headset designs/sizes have changed a fair bit over the last 10-20 years, so why not integrate disc mounts?

Since no-one has actually come up with a good reason NOT to have little discs on road bikes, I'll assume that there is none.

Or, has it more to do with UCI regulations, which ban the use of discs on road bikes?

Eh? Eh?

Got to love all you armchair experts, though. Keep it up, people, you're amusing!

This is now officially dull, although I am glad it amuses Rudeboy.

UCI regs prevent the use of discs on CX bikes. There are plenty of CX bikes around with discs. They are presumably ridden by people who do not ride UCI regulated races, and perceive performance benefits to discs.

UCI regs also prevent the use of disc brakes on road racing bikes. There are practically no road bikes with discs. We accept that their benefits to racers would be dubious. Someone has suggested they would be helpful for fat guys who don't race. Perhaps this is right, but UCI regulations are not the reason fat guys who don't race don't have road bikes with disc brakes. There must be another reason.

It is possible that fat guys who ride road bikes but don't race are idiots, although it does account for a lot of people who are otherwise quite clever. It may be that they want to look "pro", although god help them, watching the chubby guys in their sausage-skin outfits churning around Richmond Park it's difficult to imagine they think the illusion that they are a pro is maintained when they're on the bike, even if it doesn't have disc brakes.

Or, just possibly, loads of people who do and don't race, and are of a fair old range of sizxes and abilities, including a fair few bike designers have thought about the issue and decided that fitting disc brakes does not give an advantage, or no cost-effective advantage for most people.

😀

Oh, and sorry. I do not believe I am going to see miniature ickle carbon disc brake calipers built into the fork legs of the £1,000 bikes that are entirely adequate for my not-racing-very-hard needs anytime soon. Although they do sound cool...

🙂

But there is an increasing number of hybrid and 700c 'sports' bikes that are coming equipped with discs, and surely discs are what you'd want, on a CX bike? (Can we see a pic of your bike again, please, druidh?)

No, I'd say it's pretty obvious that the only reason we are not seeing little discs on 'racing bikes' (remember when all bikes with drop handlebars were 'racers'?): UCI regulations. As to why they aren't on lower end non 'professional' 'racing' bikes, is that people want something that resembles what the TDF guys have.

So, the main REAL reasons: Banned by UCI and fashion.

Thanks for the valiant attempts at answering the question, though, guys!

BD: Small things, and all that. I am easily amused, I must say. I nearly messed meself earlier, because some woman on the radio was talking a bout a mouse that stole a Malteser from her bag. It doesn't take a lot, I tell you.

But imagine, BD; really cute little discs and calipers, all shiny and nice...

I want them.

I am going to have them.

Oh, I've lost the will to live now.

there is a chicken and a egg thing going on here...

the negatives claim that, and I quote

bike designers have thought about the issue and decided that fitting disc brakes does not give an advantage

but what about the bike buying public? Why don't you let them decide whether they are a good idea?

The answer is that the bikes don't exist! You can't buy a disc-ready roadie. You can't even buy a decent disc-ready carbon fork (easily) and disc-ready 700c wheels are thin on the ground, and usually quite heavy. Only the commuter market is moving in that direction.

Oh don't be sad, aP. Do you want a hug?

[img] [/img]

Cheeze! I type in the word 'cute' in Google, and the filth! Bloody hell...

I've added another tag to this thread for you, RudeBoy.

This is a bit silly and some people are not thinking things through. Road bikes have thin little tyres that offer little grip. The brakes on them apply sufficient force already to overcome the low grip levels, so no more power is necessary.

Disc brakes weigh considerably more, they rub a bit etc. when 15 seconds separates a group of riders over a multi-week race, every gram and watt counts.

[i]I've added another tag to this thread for you, RudeBoy.[/i]

Which one???!!?

I am right and youse are all rong!

I like using my disc'd cx bike on the road (with 23mm tyres). Braking is the same whatever the weather and I can use the same wheels offroad without any issues with trueness. I don't have any interest in racing so I'm after a fast(ish) road bike with drops that can be used offroad and requires as little maintanance as possible (IME discs are always less hassle than rim brakes).

I've not had any issues with unwanted lock-ups - that's with 160mm BB7s.

I tow the kids trailer with my road bike. The 105 calipers work well enough if its dry, but discs would be nice. If I can persuade the Mrs to get me a Roadrat on her BTW scheme I'll spec that with disks.

I do not accept the argement that discs are too much for roadbike tyres. You can never have too much brake and if you lock wheels / go over the bars its not the brakes fault but your lack of skill.

Can't say I have any issues with braking with normal calipers even when towing. Road calipers do actually work remarkably well - better in general than cantis or even Vs. Meanwhile this mention of road bikes having little grip keeps coming up - strange comment when a road slick on tarmac actually has more grip than a knobbly either on road or on typical off-road.

The reason I have discs on my MTB isn't to do with power, modulation, or even working in the wet (all of which calipers or Vs are fine for), but working in mud and dirt and not wearing my rims out in said conditions.

I don't know about too much braking, TJ, but you can have sufficient, and if you can lock the rear or endo over the front then that is sufficient. A well set up caliper (which isn't that hard to manage) can do either.

aracer - even in the wet and cold? Its a long time since I have ridden with road calipers but I do remember them not working well in the wet and cold. Perhaps this has been improved greatly.

To me the main advantage of discs is not wearing rims out.

It's all down to having the right brake blocks - which have improved a lot in recent years. But even average (ie Shimano) blocks work fine in wet and cold nowadays.

Couldn't agree more with your main advantage of discs - is the principle reason I went that way on the MTB - but not a problem I seem to get on the road (some worn rims, but they are many, many years old). The only major problem I have with this now is on the cx-bike - would certainly go for discs on one of those if buying now.

The first attempt at braking after a long, non-stop ride on a cold/wet day can certainly be interesting. Seems to be much better when things have warmed up.

But I'm talking about both disks and calipers.

LOL! Love some of the tags at the top of this thread!

(Does a little dance, because none of the nay-sayers have come up with a conclusive argument against the use of discs on a roadbike)

Presumably you've missed or ignored all the comments pointing out that the system as a whole would be heavier and more expensive, and given the marginal benefits when riding a racing bike you simply can't justify those disadvantages?

What has expense got to do with anything? There are plenty of road bikes out there, that cost more than most MTBs. Which have suspension and all sorts of other gubbins, that you think would make them far pricier.

Weight? I think any weight penalty would be marginal, with careful design, and with new materials/production techniques coming out all the time, I would say that issue would be swiftly negated.

EG: XTR disc hubs are only marginally heavier than Dura Ace non-disc ones. And there are things like Tune disc hubs, that weigh less than most 'road' hubsets. Caliper/disc/lever sets, in tiny road bike rotor sizes, could be made as light as a set of road calipers, levers and cables, I'm sure. As for extra frame material, this would be offset by lighter rims, and not needing a mounting point for caliper brakes.

No, sorry, still not having it. The only real obstacles seem to be rules, stuffiness, and fashion.

Your weight calcs are out. Sure you can get disc hubs weighing not much more than 100g, but that's still 50g more than a non-disc hub. You can get caliper brakes for <200g a pair, and levers for <100g a pair, so a complete system for ~350g including cables, which is little more than one end of a lightweight hydraulic disc. How much lighter are MTB disc only rims (and how much do you reckon you could save off current <250g rims)? Have you not noticed that the mounting point for a caliper comes for free with a frame - arguably you're adding weight by not drilling the hole!

Main obstacle is still lack of any advantage.