momentum – Member

I love the idea that the main thing you'd be worried about in a 150 rider pile up at 40 miles an hour is little disc brakes – I'd be a bit more concenred about the ground!

😆

Moment of inertia? I would imagine any weight lost from the perifery of the wheel (i.e. being able to make rims with no lateral strength) would reduce moment of inertia of the wheel a noticable amount since inertia is a function of the mass and its radial position squared.

Although overall weight would be the same or maybe even greater, the advantage in acceleration would be well worth it for sprinters/ climbers i suspect.

So from my perspective as an armchair expert, I can conclude that all road frames are now strong enough to withstand disk brake use, hence why so many manufacturers are now producing road bikes with disc brakes.

Oh wait.

Have you seen this: http://www.canyon.com/_en/technology/project68.html
I think then main issue is that having disc brakes on Pro Tour level roadbike would require major changes in wheels, forks and frames. Not likely to happen anytime soon with UCI being very eh traditional about equipment.

btw, I have seen report about one local road race where one rider lost a finger in a big crash, can't remember which components caused the damage.

0091paddy – Member
So from my perspective as an armchair expert, I can conclude that all road frames are now strong enough to withstand disk brake use, hence why so many manufacturers are now producing road bikes with disc brakes.

Oh wait.

It'a quite simple. You say "road frames cannot take the forces of disc brakes".

I say "You don't know that do you?". I do not say "yes they can". Please don't mis-represent me.

As rehearsed many thimes there are ample reasons as to why no one makes high end road bikes with discs, and if you can read the thread you'll find them here…oh hang on!

It'a quite simple. You say "road frames cannot take the forces of disc brakes".

I say "You don't know that do you?".
Given I've not done a stress analysis of individual frames, no. Given disc brakes do require extra strength in the frame and forks, that extra strength means extra weight, and that low weight is one of the driving criteria behind high end frame design, then my considered opinion would be that it's so unlikely they are strong enough it's not even an interesting point of discusssion.

But disc brakes only need stronger frames if you want to slow down faster, which you don't as we've already agreed that normal calipers are powerful enough for the required rates of retardation. There's an apt word for this thread!

So you'd be designing discs with smaller rotors that would exert the same force, or bigger rotors that require less force on the bars. Where does this idea that riders pull on the brakes as hard as they can and are only saved from certain death by the poor performance of their brakes come from?

I've read everything on this thread!

I can only know what I know from what I've seen,heard and read, if a disc brakes advantages could outway the redevelopment and redesign costs of a bike, then why aren't they all over bikes that aren't intended for competition use? Audax bikes/touring bikes/sportive bikes/ etc. I know that some touring bikes have them, and the advantage there is greater modulation and power given the extra kilos carried, but that isn't the question here.

Creating a solution for a problem that doesn't exist springs to mind in this instance.

Given I've not done a stress analysis of individual frames, no. Given disc brakes do require extra strength in the frame and forks, that extra strength means extra weight, and that low weight is one of the driving criteria behind high end frame design, then my considered opinion would be that it's so unlikely they are strong enough it's not even an interesting point of discusssion.

*rolls eyes*

So if your top end road frame and fork package that your pro team are riding is 1kg under the weight limit, making you stick lumps of lead to it to make it UCI 'legal', adding 500g more carbon here and there to be able to run some newly developed road specific disks, further dropping rotational weight and massivly increasing brake performance, as well as gaining a reputation as an innovator and reams of media coverage is neither feasible, nor an interesting point of discussion?

I dont understand where this 'road frames are too light' idea comes from? and all this 'your a frame designer are you?' puffing of chests.

You simply need to look at what is out there now to see its entirely possible…

Plenty of race MTB frames can be had down at around 1kg, same sort of weight as most road frames. Road forks are around 300-400g for good ones, where as ritchey make a carbon Disc MTB fork for under 500g. Not exactly a leap up in weight (infact i reckon most stock road bike frame/fork combos weigh more than 1800g)

Indeed STRATO, I don't know where this idea that road frames are fragile comes from either, most really aren't.

Fair enough aracer, you seem to know somethng about engineering, I was having a go at paddy, to whom I would say:

How long did clipless pedals & suspension forks take to get accepted among the less change resistant mtb world? (& former in road world). How many relatively useless "innovations" are thrust upon us like smaller drive systems, low spoke count wheels, air/electronic shifting etc, in the name of coolness or progress? I'd be surprised if disc brakes don't make an entry at some point, once the market is ready and shimano don't have anything more sellable to force on us. Let's face it, micro disc brakes would look super cool!

But disc brakes only need stronger frames if you want to slow down faster

No, they need to be stronger because the forces come at a different place.

Plenty of race MTB frames can be had down at around 1kg, same sort of weight as most road frames

I'd dispute "plenty", meanwhile road frames of similar level to the 1kg MTB frames are down around 800g (conversely, I've got a 1kg Pedalforce road frame – the PF MTB frame is 1200g). I also reckon 300g to 500g is quite a significant difference in weight for a fork.

infact i reckon most stock road bike frame/fork combos weigh more than 1800g

Not high end ones – that's a good 50% more than one of those! Actually I wouldn't think even a mid/basic level carbon frame fork weighs as much as that – the ubiquitous Ribble Nero Corsa (also available with other decals) certainly doesn't.

Given disc brakes would be less aero, how does that work?

Well, if you designed a new fork with one leg (a la Cannondale Lefty) and hid the caliper potentially inside (maybe just the time trial bike) then I can see it being maybe more aero.

Kona Honky Inc Road bike. I'd buy that for a dollar.

When it come to replacing a wheel on a road bike – disc calipers are not ideal in race conditions too fiddly and not enough immediate adjustmrent. Traditional cantilever brake design wins. Otherwise valuable lessons could be lost.

I disagree, I'm pretty sure pro team mechanics could slap a wheel with a rotor into a frame in just as short amount of time as a traditional wheel, especially after some practice. If they're using a dozen sets of identical wheels, with a dozen set of idential rotors, there won't be any mismatch problems. They know which of their riders are on which wheels and would know which rotor sizes were in use by the team, so any rider using something special would be accounted for. If getting the pads snagged one side or the other while jamming the new wheel in became a problem I'm pretty sure they'd superglue the pads to the piston, or get the caliper manufacturer to come up with an integrated solution.

If the rider was unfortuante enough to need a wheel off the neutral support, they'd just be given a whole bike until they could locate the team car.

I love how road bikes are simple to look after and easy/quick to fix.
Servicing my mtb. susp. forks after 30 hrs of riding is a joke.

I hope the UCI never allows disc brakes on road races-tradition.

But it shouldn't stop us when commuting or training-but thats when cx bikes/mtb with disc brakes come in useful.

zaskar – Member

I love how road bikes are simple to look after and easy/quick to fix.
Servicing my mtb. susp. forks after 30 hrs of riding is a joke.

I hope the UCI never allows disc brakes on road races-tradition.

But it shouldn't stop us when commuting or training-but thats when cx bikes/mtb with disc brakes come in useful.

Never quite understood this logic – they should be able to use what the hell they want to use (fair enough, keep the min.weight limit) – makes life more interesting

If the rider was unfortuante enough to need a wheel off the neutral support, they'd just be given a whole bike until they could locate the team car.

I'm sure that they'd really love riding an ill fitting bike with toe clips when all they needed was a spare wheel!

they should be able to use what the hell they want to use

Fully faired recumbents for the TTs then. Or do you think there should be some rules?

Can't see it happening personally, just the ramblings of an ex-champion with too much time on his hands, a bit like LeMond really. 🙄

Agree with ADH, the amount of time lost during a race whilst compatible wheels are located would certainly outweigh the gains.

aracer – Member

they should be able to use what the hell they want to use

Fully faired recumbents for the TTs then. Or do you think there should be some rules?

within reason 🙂 Double diamond frame, min.weight limit, drop bars – after that, free reign to be be imaginitive. TT bikes are compeltely different to standard road racing bikes anyway

Fully faired recumbents for the TTs then. Or do you think there should be some rules?

Why not recumbents for the time trials? I can understand wanting something draftable for the main race, but I don't see why if there is a vastly superior type of bike for the riding you're doing, they don't want to let people use it. Assuming they're not going to make everyone ride a single completely standard bike with no component choices that is.

All that happens with all the limits, is that we get fancy bike designs that are designed to be as close to the rules without breaking them, like the various hour record breaking machines. It just means that the record is a bit slower (roughly 60% of the distance) than the unlimited hour record.

Joe

I guess the big problem with recumbents is that if they allowed them for the TT, then it'd be strange not to allow them for the race, and if they were allowed, a good rider would probably ride faster than the standard peleton, meaning it'd become more of an individual race than a tactical thing as everyone would have to have their own recumbent (can recumbents draft recumbents?).

Joe

joemarshall – Member

I guess the big problem with recumbents is that if they allowed them for the TT, then it'd be strange not to allow them for the race, and if they were allowed, a good rider would probably ride faster than the standard peleton, meaning it'd become more of an individual race than a tactical thing as everyone would have to have their own recumbent (can recumbents draft recumbents?).

Joe

You'd probably have to be mentally close together. Recumbents are ace…and utterly mental at the same time. I really want to have a go on one…just not on the road!

I'm sure that they'd really love riding an ill fitting bike with toe clips when all they needed was a spare wheel!

Well that'd be their option until they became more prevalent. Its an unlikely occurance anyway. The option to keep moving is the important one.

Agree with ADH, the amount of time lost during a race whilst compatible wheels are located would certainly outweigh the gains.

This is the opposite of what I was arguing … I doubt there would be any time lost in reality. Its just the fumbling mechanical spasticity of STW forum dwellers for you.

Fully faired recumbents for the TTs then. Or do you think there should be some rules?

They're racing 'safety' bicycles, not penny farthings, or bone shakers, or cross bikes, or recumbents, or tandems, or hippos. If you wanna race them, go race them.

i want to race hippos

They're not very good on the climbs.

he he he

i got fairly bored reading page three so i apologise if i repeat anything that has already been said.

a couple of issues i can think of whilst looking at this from a design point of view.

Where would a relatively sized reservoir be placed around the already tightly tucked internals of a road gear/brake lever?

how would you fit a rotor into a 130mm spaced rear end without flaring the chainstays and affecting q-factor as a result.

the other thing i'm thinking is that when riding in the hoods, the amount of pressure the user is able to exert isn't that great either so a more powerful brake would be a bonus.

I'm not a fan of the idea on a racebike as i'm a sub 11stone rider who's never had trouble in wet or dry.

the idea would have to be standardised completely in order for it to work as wheels would have to slot in, mm perfect in the case of a puncture. neutral vehicles carrying spare wheels wouldn't have to time centre a caliper.

I'm really neither for nor against the idea, i see it as possibly a little overkill but have nothing to back this up. i just don't need it.

It's certainly *feasible* to make a lightweight road race bike with discs but it's just not practical.
The UCI wouldn't allow it or, if they did, it would take years of discussion with riders, sponsors and manufacturers to agree to a standard and then for them to do the R&D, construction and testing. Trying to get Shimano, Campagnolo and SRAM on board to do all that would be a logistical nightmare.

Normal calipers are already more than powerful enough with loads of modulation available.

The weight thing isn't really an issue. It'd be easy enough to build a perfectly safe disc-equipped road bike at 6.8kg. A lot of pro riders now use SRM cranks or a PowerTap hub because it actually helps bring the bike inside the weight limit. There are loads of other tricks like cheaper heavier front mechs or pedals (eg Ultegra instead of Dura Ace), fitting computers or a slightly more padded saddle: it all helps with building the bike up to 6.8kg. It WAS originally due to safety concerns about drilled components but with carbon fibre and titanium it's just not an issue any more.

I'm not saying it'll never happen it's just that at the moment there is absolutely no incentive to make it happen.

Havent read the whole thread but surely the most important thing about having discs on a road bike is that they just look nice?

Tim – Member
i want to race hippos

With disc brakes… 😆

one sensible reason for not having disc road brakes is that it would be another varible for the mechanics to contend with – remember that races supply wheels in the event of punctures to riders (those yellow cars in the TdF) so it would be another complexity

They'd look terrible..

I suppose the UCI could standardise the kit (rotor size etc) so that the issues of technical support go away to an extent – everyone has the option of running discs but they have to use a standard rotor/pad arrangement so that wheels are cross-compatible – neutral support vehicles could carry both rotor and non-rotor wheelsets although you would still have issues of centering it perfectly.

That said I can't see any real chance of doing it in the short/medium term given how conservative the sport is generally and the lack of clearcut need, plus standardisation would limit innovation.

Just came across this thread, i read the whole thing as i was bored. It's interesting to read the perspective of mostly mountain bikers on a the subject of racing bikes, i'm wondering what the reaction to the idea would be a soley road forum.

Being a bit of roadie i can see some pretty glaring problems with this idea, a few of which have already been mentioned.

1) the Mavic (or other) support vehical would have a nitemare trying to get the wheels to fit your bike without the disc rubbing (any long term bike mechanic on here will vouch for that, as even same model hubs from the same manufacturer will occasionally rub the disc when swapped)- so that would cause really issues.

2) The danger aspect. Yes a spoke could cause injury, but they arn't as dangerous as a red hot (at bottom of decent etc)spinning piece of sharp steel.

3) Where are you going to use these disc brakes? coming down a mountain pass? Well you'd have to go up it first and the riders want the lightest wheels possible, so ad to the weight of the wheels a disc plus the extra spokes needed, as you can't run straight pull spokes with discs – so there go's your lightweight wheel set! (yes the rims could be a little lighter, but only by a small amount.

4) loss of areo advantage – as your now running a 2 or 3 cross spoke pattern so you'll be getting dropped on decents, not going faster due to being able to brake harder into corners (which isn't a problem anyway)

5) integrated implication – as far as i can see only the likes of cannondale would attempt it – cos they are a bit 'special' like that.

6) They just ain't needed. 😆

I still want one.

So whats the decision? XT or Elixirs?