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Old 04-02-08, 11:55 AM   #1
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disc brake pro's and con's for road bikes

There's A LOT of hype, and missinformation me thinks, concerning disc brake applications for road, commuter and touring bikes. Most heavy dudy touring riders say no. Then again, quite a few of them swear up and down that cantilever's have been 'state-of-the-art' since their inception and evey other type of brake is a pointless exercise in futility. And I can understand gram conscious racers sticking to rim brakes to save weight. But can anyone offer genuine, factual pro's and con's

Pro's: great stopping power, good wet weather performance, no rim wear

Con's: heavier, more expensive (depending on model), fewer compatible racks

I am alos interested in exactly what forces disc brakes feed into the wheel, as opposed to rim brakes, and whether or not they are necessarily harder on wheels in that respect. Do wheels need to be laced differently for disc brakes than they do for rim brakes?

Thanks. DanO
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Old 04-02-08, 03:31 PM   #2
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In my (amateur) opinion

Pros : as you have pointed out they give much better stopping power.

Cons : Alot of frames won't accept disk brakes, they aren't as user-serviceable as rim brakes/cantilevers (which is why tourers generally prefer v-brakes or canitlevers).
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Old 04-02-08, 04:30 PM   #3
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they aren't as user-serviceable as rim brakes/cantilevers (which is why tourers generally prefer v-brakes or canitlevers).
Nonsense! I don't know any brake that's easier to install and adjust than Avid's BB7 mechanical disc brakes.

And it's more than just stopping power they're good at. The power modulation and the consistency in different weather conditions are far more important factors. The lack of wear on the rim is another...

I really hope the big bike companies get going with disc brake-ready frames as soon as possible. All to gain and almost nothing to lose.
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Old 04-02-08, 05:59 PM   #4
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Discs do take a few minutes longer to service when they need servicing. But those occasions occur so much less frequently that overall discs end up being more trouble free than my Vbrakes and calipers.

Add to that the extra stopping power, linear and consistent modulation during a stop and the improved wet weather performance and we have a winner in my books.

But oddly enough I totally enjoy my rim brake bikes as well. I do it for the minimalist aspect as well as the cleaner look and to some extent the small weight advantage on a couple of my bikes.


As for the wheel loads the only real issue is that you need to stick to crossover spoke patterns on the front since the brakes are introducing drive line like torque loading through the spokes to the tires. So radial patterns spokes cannot, or at least sure as blazes SHOULD not be used with disc brake setups.
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Old 04-02-08, 06:02 PM   #5
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Another pro for disc brakes: no pad rub from an out of true wheel.
Another con for disc brakes: no brake pad to sight true on the road.
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Old 04-02-08, 06:31 PM   #6
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Another con for disc brakes: no brake pad to sight true on the road.
Uhm? Just spin the wheel and see where it moves from the middle. You don't need pads to do that!
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Old 04-02-08, 07:00 PM   #7
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My current bike is the first I've had with disc brakes. Granted, I've never had a high-end cantilever system, but on my bikes in the past, I've put on some decent brakes. In my opinion, disc brakes are it, period. The even stop, and the difference in wet conditions are really all it takes.
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Old 04-02-08, 07:13 PM   #8
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The reason there aren't more disc brakes on bikes in general = Stodginess.

Bicyclists are a very traditional crowd and "unfamiliar" technology like discs really throws a lot of folks for a loop. Once you work with them, see the advantages and learn the very little needed to maintain them, you'll use them everywhere they make sense.

For mountainbikes they are a Godsend. I raced DH on discs and can't see how you could do without them. The increased control, power and modulation once mastered will make you a better and faster rider in any discipline.

For racing bikes...no, there's no real advantage considering that braking is so sparse.

For commuter bikes...definitely nice in all weather conditions, heat or cold and may be easier to deal with regarding removing and installing the wheel.

For touring bikes...maybe not. Since discs are still a specialty item for road bikes (700c) you may not find support out on the road, though you may not need it.
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Old 04-02-08, 09:45 PM   #9
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MY TURN:

Pros: Stronger braking. Multiple pad compounds. Cable or hydraulic. Rotors take the wear as opposed to the sides of your rim, extending wheel life. More consistent stopping power in wet or muddy conditions. Cable types are pretty user friendly.

Cons: Price. Requires that you use special hubs [ adding to cost of upgrade ]. Hydraulic disc brakes can have issues with leaking [ at lever or at caliper ]. 2 different types of rotors. 2 different mounting types w/regards to frames and forks [ you don't know if you need an adapter until you try ]. Not compatible with some types of trailers or racks. If you can't work on cantilever or linear pull brakes, you won't be able to work on your disc brakes. That nice frame you have may not be designed to work with them. Weight. No standards pads, different manufacturers use different pads [ vs threadless stud canti pads or bolt on pads for some cantis and linear pull brakes ].

More when I remember.

P.S. If you were touring around the country on a bike and you had brake issues, cantilever or linear pull brakes can be repaired or replaced by a lot of mechanics. Not all of them could service or install cable or hydraulic disc brakes competently in a timely fashion. And most shops would stock more stuff for canti or linear pull brakes.
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Old 04-02-08, 09:51 PM   #10
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One other thing.

Cable disc brakes are meant to work w/ linear pull brake levers [ like the ones you see on most linear pull brake euipped mountain or hybrid bikes ]. Only one company, Dia Compe, makes a road brake lever that is compatible with linear pull or cable actuated disc brakes.

Shimano STI levers are not meant to work with cantilevers, let alone cable actuated disc brakes.

Also don't know that there is a road style hydraulic brake lever.

That's why my Trek 520 came w/Shimano bar end shifters and the Dia Compe road levers that are linear pull brake compatible [ my bike came w/Avid linear pull brakes ].
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Old 04-02-08, 10:24 PM   #11
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Cable disc brakes are meant to work w/ linear pull brake levers [ like the ones you see on most linear pull brake euipped mountain or hybrid bikes ]. Only one company, Dia Compe, makes a road brake lever that is compatible with linear pull or cable actuated disc brakes.

Shimano STI levers are not meant to work with cantilevers, let alone cable actuated disc brakes.

Also don't know that there is a road style hydraulic brake lever.
Actually, the Avid BB7 now comes in a "road" version which is meant to work with the cable pull offered by standard road levers, such as the STI, Ergo, or whatever. You can use whatever road levers you want when you use the road version of the calipers.

It is true that there is no hydraulic road lever available right now. But that is much more niche of a product. There are lots of "road" riders that could benefit from disc brakes, but very few that could benefit from hydraulic disc brakes. For myself, even if hydraulic road levers were available, I still would have gone with the cable actuated BB7s.

-Sam
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Old 04-03-08, 12:46 AM   #12
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Kona built a bike called the Sutra that we stocked at a shop I worked in. It was a full 105 touring bike with Avid BB-7 road brakes. This was a great seller here in Washington because the discs added better wet weather performance and less rim wear for winter commuting. They do weigh more. And any decent shop will be able to work on a cable brake. They are as simple to adjust as a linear pull brake. The pads will last longer on a disc than any caliper brake. For a touring or winter commute bike, disc brakes make a lot more sense to me than calipers.
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Old 04-03-08, 12:53 AM   #13
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.... For a touring or winter commute bike, disc brakes make a lot more sense to me than calipers.
Ah yes... The famous Pacific North"WET" region... That's why I went to discs on a couple of my bikes. The good ones don't even know when they are wet. You gotta luv that!
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Old 04-03-08, 01:02 AM   #14
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MY TURN:

Pros: Stronger braking. Multiple pad compounds. Cable or hydraulic. Rotors take the wear as opposed to the sides of your rim, extending wheel life. More consistent stopping power in wet or muddy conditions. Cable types are pretty user friendly.

Cons: Price. Requires that you use special hubs [ adding to cost of upgrade ]. Hydraulic disc brakes can have issues with leaking [ at lever or at caliper ]. 2 different types of rotors. 2 different mounting types w/regards to frames and forks [ you don't know if you need an adapter until you try ]. Not compatible with some types of trailers or racks. If you can't work on cantilever or linear pull brakes, you won't be able to work on your disc brakes. That nice frame you have may not be designed to work with them. Weight. No standards pads, different manufacturers use different pads [ vs threadless stud canti pads or bolt on pads for some cantis and linear pull brakes ].

More when I remember.

P.S. If you were touring around the country on a bike and you had brake issues, cantilever or linear pull brakes can be repaired or replaced by a lot of mechanics. Not all of them could service or install cable or hydraulic disc brakes competently in a timely fashion. And most shops would stock more stuff for canti or linear pull brakes.
Ever heard of mechanical disc brakes? No problem with leaks or brake fluid. Simple cable stuff, just like vees and cantis.
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Old 04-03-08, 04:23 AM   #15
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You also have to give the fork some consideration. You need a somewhat chunkier fork design to cope with the forces generated by a hub brake as compared to those generated by a rim brake.
There are also those rare but highly publicized cases where front discs are suspected of contributing to front wheel ejection during braking ASO.
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Old 04-03-08, 05:07 AM   #16
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I have had horrible experiences with hydraulic disk brakes. The bleeding is hard enough, but then there is pad alignment which I can never get to work, either the pads are too close or too far from the disk. Sometimes they engage the disk at different times so they push the disk slightly.
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Old 04-03-08, 05:21 AM   #17
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Shimano STI levers are not meant to work with cantilevers, let alone cable actuated disc brakes.
My 105 STIs work just fine with my cantilever brakes. I think it's V brakes that STIs won't work with.
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Old 04-03-08, 05:52 AM   #18
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Yep, I have a few bikes with Cantilevers and aero road brake levers. Good to know STI's work too.,,,,BD
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Old 04-03-08, 07:33 AM   #19
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Riders in hill country may find the heat rejection to be superior with discs over rim brakes. I have seen rim brake equiped bikes with tires that were partially melted onto the inside of the rim. This is very close to a blown tube at speed.
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Old 04-03-08, 08:10 AM   #20
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My 105 STIs work just fine with my cantilever brakes. I think it's V brakes that STIs won't work with.
Mine do too and you are correct. V-brakes won't work with STI/Ergo/road levers unless you use Travel Agents or a similar cable travel adapter.
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Old 04-03-08, 11:05 AM   #21
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You also have to give the fork some consideration. You need a somewhat chunkier fork design to cope with the forces generated by a hub brake as compared to those generated by a rim brake.
True, but not that much.

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There are also those rare but highly publicized cases where front discs are suspected of contributing to front wheel ejection during braking ASO.
Yes, but that is easily solved by making the dropouts point forward and a little bit down, instead of mostly down. The force of the disc brake will then act almost perpendicular to the dropout.
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Old 05-20-08, 12:57 AM   #22
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I love the idea of road disc. I set up my rain bike with them, and they are GREAT.

I am a mechanic of about 2 years now, and I know that one negative of the bike industry is Dogma. MANY people rip on new ideas without any knowledge or experience with the the technology.

Pro's: STOPPING POWER in any weather, no rim wear, last longer in bad weather, (all of which really help here in seattle.).

Cons: Weight, price(IF CONVERTING, not soo bad if using initially), Compatibility issues.
However; compatibility is a bad reason to avoid a good idea. Like BB30, which people still reject because of compatibility/specialty, but is catching on FAST. Road disc is catching on.
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Old 05-20-08, 01:36 AM   #23
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Weight has been coming down to a point where disc brakes isn't that much heavier than rim brakes. Just check the numbers at weight weenies.

Like rim brakes, disc brakes are not all equal. So it would depend on what the bike was equipped with or the components you plan to purchase/can afford.

I can see disc brake equipped or 'disc ready' bikes becoming more popular with the general public, with road and touring bikes included. Depends on the demand for it and of course...offering disc brakes at most price points that can fit into an individual's or family's budget.
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Old 05-20-08, 06:53 AM   #24
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I am a fan of discs. I dropped a lot of money on my Hopes and they are ruddy good. However, with the light frame and skinny tyres, surely discs would just mean that wheel lock up occurs faster and more frequently. I can easily lock up my rear with standard Ultegra STIs and calipers. Do I ever? No, because I like my tyres to be round.

I also think that discs look really good on mountain bikes (especially on my MTB ) but I really don't think they would look good on an elegant road bike.

Just my opinion but I think a lot of roadies would agree.
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Old 05-20-08, 06:58 AM   #25
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Cons: Both wheels have to be built with enought dish, both front and back to accomodate the disc. Weaker (somwhat) front wheel, can't use radial spoking. The back will have to have dish both sides and make for a weaker wheel laterally.
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