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Disc brakes and road bikes...(19 posts)

Disc brakes and road bikes...Black Johnny
Nov 12, 2002 11:21 PM
Evening everyone.
So I had a chance to ride a friend's disc brake specific Gunnar fixed gear tonight and it was really nice. Really, really nice. Now I am ready to do up a road bike with disc brake wheels but am having a hell of a time finding a disc hub that will take Campy 10. Anyone have any ideas? What is the general concensus regarding disc brakes on road bikes anyways?

Thanks,
bjb
what about you put disc only on front ?PeterRider
Nov 13, 2002 12:15 AM
re: Disc brakes and road bikes...{sarcasm warning}Spunout
Nov 13, 2002 4:54 AM
What do you dislike about a Chorus/Record brake caliper?

Can you: Break loose the front tire and skid into a ravine?

Can you: Hope to get enough braking power to go over the handlebars and faceplant the asphalt?

Can you: Get similar performance in wet weather?

Can you: Get excellent modulation in order to hang in the pack on a mountain descent?

I can do all the above without discs. Disc brakes will do all of the above, just a bit sooner though.
I'm with Spunout on this oneAllez Rouge
Nov 13, 2002 5:42 AM
Disc brakes make sense for off-road bikes when the going gets sloppy, but for road bikes they've always struck me as the answer to a question no one asked. After all, road bikes already HAVE disc brakes. Think about it: what else would you call a 700c wheel being pinched between a pair of lever-actuated shoes?.

If you're unhappy with your current braking performance or characteristics, I would recommend trying different brake shoes.
Disagree with you both.Winona Rider
Nov 13, 2002 6:38 AM
With respect of course.

If you are riding lots in the rain on dirty roads, and are fairly big, you will fully appreciate the benefits of a disc as you head downhill on a winter's night.

Wet riding/commuting = oil on the road = on your rims/brakes = poor performance, even with the best well adjusted calipers and shoes. Cleaning it all off after ever journey is just not an option for most folk.

A disc solves most of that. I would find one a real bonus for winter riding. I do in fact, when I ride my MTB on the road.
you said it besttrekkie1
Nov 13, 2002 7:02 AM
If you need disc brakes, you probably also need a mountain bike, with it's wider tires -- and likely fenders, too.

Road tires are just too darn skinny to really take advantage of disc brakes. The weakest link in the braking chain is traction on a road bike, and better brakes won't do a thing. There may be exceptions in very unusual circumstances, but it's sort of like getting full time 4 wheel drive when you live in Miami.
Still don't agreeWinona Rider
Nov 13, 2002 7:40 AM
I commute on 28s. They grip plenty. However, on a wet winter downhill even the cantis on my CX can run out of grip - they take a long time to bite and haul up my 230lbs -they are the weak link, not the tyres. Plain road brakes don't have a chance.

Furthermore, I don't wanna have to be in the drops hauling levers with 4 fingers to get my breaking in.

Some folks have different requirements.
230 lbs?Straightblock
Nov 13, 2002 9:53 AM
Geez, Winona, I never would have guessed. And they say the camera ADDS 10 lbs!
All that shopping in my pockets is heavy. nmWinona Rider
Nov 14, 2002 1:37 AM
Clueless in Miamigrzy
Nov 13, 2002 9:23 AM
It appears you've never driven a Subaru WRX, or similar, on "normal" roads. Otherwise you'd know the advantages of full time AWD under *any* conditions.

The key with disc brakes is the increadible amount of control and modulation that they provide. Not everything is a panic stop at the limit. On the contrary, disc brakes allow a much more precise level of braking under any conditions. I know this is a little hard to accept in the pure roadie world, but those of us with one foot in the MTB world and have messed around with various braking systems over the years have a different view on this.
you know what they say about assumptionstrekkie1
Nov 14, 2002 8:46 AM
Actually, I drive a 220 hp AWD car (albeit 500 pounds heavier than a WRX) with traction control and stability control - almost idiot proof. I've also driven everything from FWD to 4WD, RWD, and mid-engined cars, including formula race cars (in the rain, no less).

Yes, AWD is helpful. Is it necessary? Hell no. Plus, it adds weight and complexity. While it is helpful in certain conditions, many cars can be faster in some conditions without it. Check out 911's. To make a fast car for most drivers, they use AWD. To make a really fast car, they omit it.

No doubt certain conditions and types of cars merit AWD. Rally cars, high powered road circuit cars -- sure -- but these are more analogous to mountain bikes and cross bikes. Road race bikes are more like light weight formula cars, at least in my view/experience. Try adding AWD to a 110 HP Formula Ford and the car would get slower in all conditions, save pouring down rain.

Disc brakes on a road bike could be nice, but what is the cost/benefit? The cost is likely more money, more weight, and compatibility issues. The benefit is better braking in some limited conditions. I've road races for 20 years, and I can think of extremely few times when better braking would have made even a few seconds difference in a race.

I will concede, though, with the new all carbon rims, particularly ultra light tubular ones, disc brakes will make more sense.
Limited conditions?Winona Rider
Nov 14, 2002 9:04 AM
I assume that it's nice and dry where you live then? (Or at least you don't ride in the rain much).

Cost? Seen the price of campy/DA capplipers - you can get a cable disc set-up cheaper.

Weight? Who cares - what's the point of being light weight and stuffed into the side/back of a truck? And what are we talking - a lb, mebbe 2? And that's without carbon discs and Ti bolts/capliers.

Compatibilty? MTBers seem to manage fine.

Look ahead - they are coming to a bike near you soon. They are on MTBs. They are on CXers. They are on hybrids. They are only moving one way...

You are right about AWD though - it will be years before we see that on bikes :-)
big concession heretrekkie1
Nov 14, 2002 10:42 AM
If were are not talking about racing, they who gives a rat's ass about weight. For joe club guy doing centuries, an extra 100 grams (or whatever) due to the disc brakes or beefed up frame/fork to handle them is pretty much irrelevant. Also, even for racers, if I rode in mountains, especially rainy weather mountains, I'd strongly consider them, too.
...and limited experience! ;-)grzy
Nov 14, 2002 10:46 AM
Trekkie1 doesn't seem to have much in the way of disc brake experience on bikes. Kinda wonder if he'd be willing to drive any of the mentioned cars with drum brakes and forgoe the discs? All the power and speed is nothing without control. That he's willing to drive a heavier AWD car lends credibility to the idea that people will accept the higher weight of a disc brake ride. My full suspension MTB with disc brakes checks in at 25 lbs. - less than many hard tails and not too far from some road bikes.

I guess one of the bigger issues is the fact that most of the roadies seem to think that they all know better....on just about everything. Talk about resistant to change - you practically have to beat them over the head with a better solution and then pay some pro to ride and win with the product. In the end they'll all line up like a bunch of lemmings and fork over all of their money for the latest gadget even if it's based on junk science and pure hype.

One doesn't need to be a rocket scientist to realize that the MTB has probably been the best thing for the road bike. A lot of the long established assumptions have been tossed in the trash. Where did the threadless headset come from? Splined BB - you saw it first on XTR. Ksyrium wheels are just a road version of the MTB wheel. Remember all those people that didn't think you'd even need a suspension fork on an off road bicycle or that full suspension would never be light enough or efficient to be a good cross country ride - where are they now? Avid already makes a cable disc caliper that will work with normal road levers. All that's needed is a suitable frame and fork which can be obtained by a custom builder.
ya ya yatrekkie1
Nov 14, 2002 11:25 AM
You are right that mtb's have heavily influenced road bikes in the last 10 years or so. However, I don't think that necessarily means that everything good for mountain bikes is also good for road bikes. There are some key differences, the primary ones being surface smoothness and traction.

Smoothness, or the lack thereof, means suspension and better brake modulation is helpful, even with added weight.

Also, mtb trails require tons more braking than just about any road I've ever seen; I've done a bit of mtb racing, too (nope, not with disc brakes), and you damn near can wear your hands out braking, especially if you are a big chickenshit on the descents; I've never experienced anything even close on the road. Heck, there are times I've ridden a century on a road bike and never would need to touch the brakes if it weren't for stop signs (and how often is emergency braking power/modulation necessary pulling up to stop signs?).

Suspension, as well, can help on some road bike conditions, but what are we talking about here, 1% of riders or conditions?

Yes, I use an AWD car. However, it's certainly not a race car, so extra weight is damn near irrelevant.

As to your inquiry about driving a car with drum brakes, yes, I have. They totally suck (even Enzo admitted as much after getting his butt kicked)! However, two things: 1. caliper road bike brakes are not the equivalent of automotive drum brakes; and 2. cars have tons better tire adhesion available for braking compared to a bike, and have tons (literally) more momentum requiring better heat dissipation and braking power. Road bikes have little bitty contact patches (like 1 square inch, I think) and rarely challenge the heat dissipation properties of conventional brakes/rims.

Yes, again, I'll concede disc brakes for road bike can be beneficial in some circumstances, I just doubt they will ever become ubiquitous. It seems the first place you'd see them, actually, would be tandems, where even now they generally only appear as auxiliary drag brakes.
ya ya yaweiwentg
Nov 14, 2002 12:24 PM
also, heavier rims will be required, as well as hubs. I do ride discs on my MTB, but in their present incarnation I don't really see them as necessary on road bikes. the aero drag factor would also increase.
of course, if someone designed a 60mm rotor and very small caliper, they might catch on.
Two thoughts....TFerguson
Nov 13, 2002 7:21 AM
1 - It seems that the debate on whether they are worth the effort comes from center pull (road/narrow tires) saying you don't need them and canti (touring/CX/wider tires) saying yes I do. This really isn't a debate.

2 - I've been trying to watch the disc/road developments closely (I ride cantis/Vs with travel agent) and it seems that the fork may be the problem everybody runs into. You need a very stiff fork so that all the torque applied at the end doesn't shove it right back into the downtube. A fork this stiff probably weighs as much as a rigid MTB fork and rides like a tank when compared to a common road fork.

As far as your Campy 10 speed - The only way I know would be to use a Shimano compatible disc hub and one of the Shimano to Campy cassettes (i.e. Wheel Mfg). The hubs, however, will be spaced at 135 mm so you would need to use a 135 mm road frame, stretch a steel 130 mm frame or modify the hub by removing spacers and/or changing out the freehub body.

TF
Interesting comments from many.Black Johnny
Nov 13, 2002 1:29 PM
I would agree strongly with the above post regarding the possible fork issues and the weight. There are no complaints though, with the Record calipers in the dry but the disc out perform them in the wet hands down. In the end this may make this application of disc brakes somewhat regional. Never the less the trend is growing. Heavier riders would very much appreciate the additon of disc wheels I think as well. Thanks for the Wheels Manufacturing idea for the cassette. I may just end up building a 9spd rig for this instead.

Cheers all.
bjb
Just do it!Jaybo
Nov 13, 2002 4:02 PM
I have disc's on my mountain bike that rock! I love 'em. Why not put disc's on road bikes. I like to stop quick when road biking; however, those darn brakes love power in anything but dry weather. Even then, I yearn for more power. Disc's on road bikes would rock! End of story