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Disc brakes on road bikes...

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Disc brakes on road bikes...

17 Dec 2011 21:49

Velonews has a good article regarding disc brakes on road bikes. Seems carbon wheels (I know there was discussion about his here earlier) might help force the switch.

http://velonews.competitor.com/2011/12/bikes-and-tech/the-torqued-wrench-disc-brakes-coming-soon-to-a-drop-bar-near-you_200057
richwagmn
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17 Dec 2011 22:21

Yep, we did discuss before, been a while tho. D-brakes are coming to road as soon as the standards for rotor size and hub spacing are figured out. The biggest problem with carbon rims has been the braking performance, D-brakes solves that. Weight issue is zero, if riders are willing to take on the heft of a power metering system, D-brakes are a drop in the bucket in terms of total added weight.
User avatar RDV4ROUBAIX
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18 Dec 2011 00:01

Interesting read there, including the comments in the link. Seems like the spacing issues would be much easier to overcome for the front wheel. This might sound a bit crazy, but how about putting the disc on the front but keeping the rim brake on the rear? That might have helped poor Beloki in the 2003 Tour.
User avatar on3m@n@rmy
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18 Dec 2011 00:18

on3m@n@rmy wrote:Interesting read there, including the comments in the link. Seems like the spacing issues would be much easier to overcome for the front wheel. This might sound a bit crazy, but how about putting the disc on the front but keeping the rim brake on the rear? That might have helped poor Beloki in the 2003 Tour.


Yes, a few commenters suggested just that.

I wonder if a hydraulic system is really necessary. Do they not operate well with cables?
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18 Dec 2011 00:19

I'm sure we have a thread on this already. Some mod should find it :D
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User avatar ElChingon
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18 Dec 2011 05:43

richwagmn wrote:Yes, a few commenters suggested just that.

I wonder if a hydraulic system is really necessary. Do they not operate well with cables?


The general consensus is hydraulic systems are smaller/lighter than trying to do the same thing with cables.

I don't know how they could get the hydraulic stuff inside a brifter though. My guess is the cylinders will be inline somewhere for quite a while.
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18 Dec 2011 14:01

RDV4ROUBAIX wrote:Yep, we did discuss before, been a while tho. D-brakes are coming to road as soon as the standards for rotor size and hub spacing are figured out. The biggest problem with carbon rims has been the braking performance, D-brakes solves that. Weight issue is zero, if riders are willing to take on the heft of a power metering system, D-brakes are a drop in the bucket in terms of total added weight.


But of the road bikes sold in the US or anywhere else, how many have carbon wheels? Seems like a BIG change, to the forks, frames, hubs, levers, for a relatively small segment of the bicycle 'population'. Very marketing driven, or it will be.

I see real advantages for segments of bicycles. Cross, touring, MTB, tandems, not so much for that $1500 road bicycle with aluminum rims.
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18 Dec 2011 15:41

Bustedknuckle wrote:But of the road bikes sold in the US or anywhere else, how many have carbon wheels? Seems like a BIG change, to the forks, frames, hubs, levers, for a relatively small segment of the bicycle 'population'. Very marketing driven, or it will be.

I see real advantages for segments of bicycles. Cross, touring, MTB, tandems, not so much for that $1500 road bicycle with aluminum rims.


By removing the need for a wheel to also be a good brake surface, wheel materials and design can adapt to the mechanical side of holding a tire on the rim without also needing to dissipate heat and last long enough to not wear out from the brakes. By removing that 1 parameter in design manufacturers can explore other materials that would be lousy at friction or heat but might add strength to the wheel? Maybe the other result is cheaper. Plus the makers are not worked about the braking skill of their customers either.
Disk only wheels are more and more common amongst MTB riders and they are lighter for the design change.
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18 Dec 2011 16:31

on3m@n@rmy wrote:Interesting read there, including the comments in the link. Seems like the spacing issues would be much easier to overcome for the front wheel. This might sound a bit crazy, but how about putting the disc on the front but keeping the rim brake on the rear? That might have helped poor Beloki in the 2003 Tour.
It wouldn't have made a blind bit of difference to Beloki. His crash wear due to the tarmac melting not to his rims overheating.
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18 Dec 2011 16:46

ultimobici wrote:It wouldn't have made a blind bit of difference to Beloki. His crash wear due to the tarmac melting not to his rims overheating.


Yeah I knew the tarmac was hot and melting. But I never heard the final conclusion on why it happened. In the replays you could see the rear tubular coming off the rim, but I did not know if it was because of the tarmac causing the bike to fishtail or the rim glue getting too hot and melting. I was thinking maybe the latter.
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18 Dec 2011 16:59

on3m@n@rmy wrote:Yeah I knew the tarmac was hot and melting. But I never heard the final conclusion on why it happened. In the replays you could see the rear tubular coming off the rim, but I did not know if it was because of the tarmac causing the bike to fishtail or the rim glue getting too hot and melting. I was thinking maybe the latter.
That would fly if we were talking about an inexperienced rider who used his back brake to that extent. But we're talking about a professional so it's unlikely. With sticky tarmac the tyre wouldn't skid, instead it would catch and rip the tyre off the rim. Beloki was simply unlucky that he hit a wet/sticky patch of tar and Armstrong & co lucky they didn't.
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18 Dec 2011 17:07

Funny thing about disc brakes is that despite them being legal to race on in cross, not one top level european circuit rider is using them. Why is that?
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18 Dec 2011 19:16

Bustedknuckle wrote:But of the road bikes sold in the US or anywhere else, how many have carbon wheels? Seems like a BIG change, to the forks, frames, hubs, levers, for a relatively small segment of the bicycle 'population'. Very marketing driven, or it will be.

I see real advantages for segments of bicycles. Cross, touring, MTB, tandems, not so much for that $1500 road bicycle with aluminum rims.


I get what you're saying, but I'm just trying look ahead a few years when the inevitable happens and D-brakes become more refined for CX and road use, more options than just the 2 from Avid at the moment. I'm sure we're all in agreement that it d-brakes benefit carbon wheels the most, but I think D-brake specific alloy road rims are going to be plentiful as well. I bet some very cool designs will come out of this too.

It's all about options for whatever situation, rim brakes aren't going to disappear anytime soon, they'll have their place for a long time. I for one would love to have a CX/Gravel racer with D-Brakes. Santa is almost here, Moots' PSYCHLO X is on my list. ;)
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18 Dec 2011 19:34

Master50 wrote:By removing the need for a wheel to also be a good brake surface, wheel materials and design can adapt to the mechanical side of holding a tire on the rim without also needing to dissipate heat and last long enough to not wear out from the brakes. By removing that 1 parameter in design manufacturers can explore other materials that would be lousy at friction or heat but might add strength to the wheel? Maybe the other result is cheaper. Plus the makers are not worked about the braking skill of their customers either.
Disk only wheels are more and more common amongst MTB riders and they are lighter for the design change.


Vast majority of aluminum rims hold the tire fine, don't heat to the point of blowing off tires and die when they get bent or dented, rather than wearing out a sidewall.

PLUS the advantage to MTB are things that are seldom seen on a road bike, a road bike, not cross or tourer...wet, muddy, crappy conditions and high chance of wacking a wheel.

Disc brakes, wheels, frames, hubs will never be as cheap as rim brakes. I've seen rim brakes for $15, new, Tektro and they work OK.
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19 Dec 2011 01:28

it took a while for elite xc racers to shift to disc brakes too. weight was an issue initially. in addition, as far as i know, only avid makes road-specific disc calipers so if a rider is sponsored by shimano or colnago, he or she probably isn't going to use them.

ultimobici wrote:Funny thing about disc brakes is that despite them being legal to race on in cross, not one top level european circuit rider is using them. Why is that?
funnytanlines
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19 Dec 2011 02:11

Will the front disc change the ride quality in anyway? Just curious because it seems the fork would need to be beefed up to handle the stresses which may impact feel. Heavier, more rigid front end. Or maybe this is all a non-issue.
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19 Dec 2011 03:58

Bustedknuckle wrote:Vast majority of aluminum rims hold the tire fine, don't heat to the point of blowing off tires and die when they get bent or dented, rather than wearing out a sidewall.

PLUS the advantage to MTB are things that are seldom seen on a road bike, a road bike, not cross or tourer...wet, muddy, crappy conditions and high chance of wacking a wheel.

Disc brakes, wheels, frames, hubs will never be as cheap as rim brakes. I've seen rim brakes for $15, new, Tektro and they work OK.


Lets look at the equipment racers are using and not how cheap a part can be made. No one is racing on 15 dollar brakes nor are many top racers using aluminum rims. So we aspire to greater access to exotic materials at lower price points. A lot of modestly priced road bikes are less than 20 pounds but not cheap bikes yet.
In the sport of cycling the rules shape the material to a large degree. Frame shapes, weight and in this case brakes. There has been no demand for road bikes with disk brakes but at some point racers will chose based on performance and weight will be a moot argument.
As the parameters change so will the result. As it stands today disks are a weight penalty. They are currently not much of an advantage for most courses but are much less a penalty today than a year ago and 2 years ago it was against the rules.
In another year the equation will have many new variables.
One other point about price.
Take the most technically advanced bike from 1986 and compare it to a $2500 bike of today. I think the bike of today will be as light or lighter, will be stiffer, will have 4 more cogs, and enjoy a lot of things that were not available in 1986 at the dawn of clippless pedals and index shifting.
Actually this argument is inane and almost every time somebody demands a technology is a waste of effort or it won't take hold or it is too expensive that they get proven wrong or miss the mark. Eventually all technology gets cheaper as it gets more expensive and exotic.
You can still buy $5000.00 computers but almost any $500 computer built today outperforms a 5 year old computer that was $5000 new
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19 Dec 2011 06:27

craptastic wrote:Will the front disc change the ride quality in anyway? Just curious because it seems the fork would need to be beefed up to handle the stresses which may impact feel. Heavier, more rigid front end. Or maybe this is all a non-issue.
Definite issue. The forks need to be reworked to take the extra stresses of the brake.

With rim brakes the strength needs to be concentrated at the crown/rim area, with discs this area still needs to be strong but the fork blades need reinforcement at the mount as well.

I think what many are overlooking is that the braking needs on a 7kg road bike is very different to that on a slightly heavier mountainbike. A lot of work still needs to be done on the modulation of disc brakes for road use for starters, as well as the actuation method. With electronic shifting taking appreciably less space in the levers, hydraulics can't be far away.
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19 Dec 2011 09:48

there are already full carbon cross country and cyclocross disc forks out there, so the technology is available. there are lightweight carbon 29er rims as well, which, when adapted to road widths, should be lighter the current carbon rims because they won't need a brake track. the only obstacle right now is the availability of mechanical disc calipers from shimano & campy, or hydraulic + electronic sti/shifters from the shiimano, campy & sram.
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19 Dec 2011 13:48

craptastic wrote:Will the front disc change the ride quality in anyway? Just curious because it seems the fork would need to be beefed up to handle the stresses which may impact feel. Heavier, more rigid front end. Or maybe this is all a non-issue.


There are going to be a lot of frame and fork changes if road discs happen.

PLUS the issue of aligning the rotor size to the caliper position, sometimes an issue with MTB. PLUS hubs, levers(if hydro), etc. MUCH bigger change than to MTBs.
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