disc brake on touring/commutor bike
 

Looking at a new Gunner Sport and wondering if mechanical disc brakes would be a better choice. (LBS has Tektro 521AG long reach brake calipers speced). What are pros and cons of discs. Because I do ride alot of the "Rails to Trails" with the limestone gravel I do get alot of dirt onto the rims and the brakes tend to grind it into the rims. Also assume discs would work better in wet weather. Do discs add significant rotational weight. Is that why they are not used on road bikes?
Mostly shimano 105 or Ultegra components on the rest of the bike any other thoughts on specing, only going to get one chance to do this correct the first time.
Point me in the correct direction!!!!!!

This has been debated into the ground. And you won't find any absolute truths with regard to disc brakes, except the fact that they stop better in the wet. Maybe you should try a search?

Disc brakes are not commonly found on road bikes because they are not commonly needed or desired. They add expense, complexity, and weight. They are also banned from UCI racing events.

My opinion - if you plan to ride often in gravel and the rain, then disc brakes are a good idea. There is a small weight penalty and your bike may ride a bit rougher due to the stiffer fork, but this will probably be a worthwhile trade-off for you.

Disc brakes make sense on all bikes, except for a very small number of special cases (pure climbing bikes and track bikes for example). It's really only fear of change that prevents universal adoption of a vastly superior brake technology for all bikes.

If they indeed are banned by the UCI, then it's a tragedy. That will delay disc brakes many years longer than necessary.

I would even go so far as to say that it should be LAW that all bikes operated on public streets/roads should be fitted with a disc front brake (minimum).

Just FYI... UCI bans disc brakes in mass start races due to concerns over riders getting cut up from the disc rotors during accidents. I think the ban makes sense... I'd hate one of those rotors to sink into my calf, Spartacus-chariot style.

Like the chainrings are any less dangerous in a crash, it's not like the discs are razor sharp.
UCI was never about innovation, besides, there is a big market for discs in the mountain category.

Whatever. I'm not here to argue... it's pointless anyway. Just stating the facts.

Why I will only use disc brakes:

no rim wear so no rim replacement every 6 months
consistent braking no matter what the weather and roads/trails are like
masses of power and great modulation
VERY simple to setup, adjust and use
no hassle changing/removing wheels (open skewer, remove wheel, replace wheel close skewer - no F. about with cables or brake release)
no rim contact so no worries with out of true wheels
no grabbing or pads wearing so fast you have to replace every 2-3 weeks (especially with wet, gritted roads or muddy trails)
MUCH easier than cantilevers to install, adjust and maintain

disc brakes only

road bikes with disc brakes

trek portland - http://www.trekbikes.com/us/en/bikes...land/portland/

cannondale cross xr7 - http://www.cannondale.com/bikes/08/c...del-8XR7C.html

Brodie romax - http://www.brodiebikes.com/2007/2007_bikes/romax.php
brodie ronin - http://www.brodiebikes.com/2007/2007_bikes/ronin.php

lemond poprad disc - http://www.lemondbikes.com/bikes/cross/poprad_disc.php

rocky mountain sherpa - http://www.bikes.com/bikes/2007/TOURING/sherpa-10.aspx

kona sutra - http://www.konaworld.com/08_sutra_w.htm

orbea diem drop disc - http://www.orbea.com/ingles/interior...ilia=6&gama=13

focus cross disc - http://www.focusbikesuk.com/focuscyc...cross_disc.php

devinci caribou2 - http://www.devinci.com/10479_an.html

raleighusa sojourn - http://www.raleighusa.com/items.asp?deptid=5&itemid=427

rei novara element - http://www.rei.com/product/744808

co-motion mazama - http://www.co-motion.com/mazama.html

rocky mountain Solo CXD - http://bikes.com/2008_preview/2008_preview.html

rotwild rs1cx - http://www.rotwild.de/en/ (street bikes section)

fixie inc. pureblood - http://www.cycles-for-heroes.com/200...pureblood.html

maxx roadmaxx custom (you choose the color and parts at the LBS and the factory puts it together, i.e., not a custom frame) - http://www.maxx.de/frmain_bikes.htm (road - roadmaxx custom)

Salsa la Cruz - http://www.salsacycles.com/laCruzComp08.html

I couldn't have said it better myself!

Besides, I doubt a road-specific disc brake would be that much heavier than the extra mass on the rims to allow for wear, the brake caliper itself and the brake pads. Also, more of the mass is moved to the hub, lowering rotational intertia, which should make acceleration a bit faster in the ideal case.

Better modulation on a road bike would probably mean more efficient braking, which could be used to go faster into a turn, saving time.

Thanks everyone for your input. I will check out some of the links.

TMK most laws ban disc brakes because of their tendency to not lock the front wheel. Bicycle break laws, when they exist, often state it must be capable of locking the front wheel while moving at speed (see: Bicycling and The Law).

But seriously, please don't talk to anyone in legislature or city council, EVER. We don't want to be told what kind of brakes we have to have.

Get the Gunnar and a cx disc fork for the front.

I guess that goes for every piece of equipment then, eh? Maybe no brakes at all, no lights, no reflectors? No, I really would like to see a front disc brake as a legal requirement for regular bikes. Bikes taking part in bike races would be exempt.

Well, I use discs and really don't want to switch back to rim brakes, for all the reasons given above. However, seems to me it's not "all gain, no loss". With f/r discs, you inherently have much more dishing both front and rear, in addition to rear drive-side dish if running a cassette. Thus, wheels are inherently quite a bit weaker -- no way around this. I don't worry much, running 26" (559 rims) wheels, but I would think a bit more of an issue with 700c?? Dunno, but intuitively strikes me as a consideration. I also second the comment about fork rigidity and ride quality; any rigid 700c bikes running discs that I'm familiar with do seem to have to have an overbuilt fork, to cope with the braking forces, relative to a version with rim brakes. Compare, e.g., a Trek Soho/disc with, e.g., a Trek fx bike, which uses v-brakes.

I would even go so far as to say that it should be LAW that all bikes operated on public streets/roads should be fitted with a disc front brake (minimum).

I think all bikes should be equipped with brakes but legislating the use of one good brake over another good brake would be ridiculous.

It's the other way around - disc brakes mean less wheel dish. The hub flange spacing may be slightly narrower than a non-disc hub though.

This is a good post... a really balenced point of view. I would like to add that rim replacement need not be more expensive than disc replacement, if you can build your own wheels.

But honestly, despite their drawbacks, I would love to have a disc brake equipped bike to use on rain days or in snowy weather. I'm buying an IRO Rob Roy frame as a part of the BF group buy. My plan is to get a Surly disc fork and run a front avid disc, and keep the rear wheel brakeless (as a fixed gear).

States which require brakes have vague requirements, usually just outlining performance. And the way they outline it isn't even very good. But thankfully they never specify a technology!
Mandating disc brakes now would be akin to mandating rim brakes at the turn of the last century (and yes, it was a big battle over whether or not bikes should have them). Had those brakes been mandated you wouldn't see disc brakes now: Because it'd be illegal to put them on a bike since they're not rim brakes.

While I can't tell you what the next big braking thing will be, I can tell you there will be another big braking thing. And it might not legally be disc brakes. Since law is notorious for being unable to keep up with technology why mandate a technology?! You'll do more to hold technology back than save anyones suicidal butt.

Some places don't require lights, and reflector requirements are a joke: THEY DON'T WORK. That's why light requirements are as common as they are. Equipment requirements suck.

Anyway, my rim brakes will lock both wheels. I have never had a problem stopping quick enough on my 23's with caliper rim brakes.
I wouldn't mind seeing a regulating body do something about low end bikes with brakes that just aren't very effective. The minimal thing would probably be to keep a list of bikes with ineffective brakes so LBS can skip buying those models.
I get tired of reading low end reviews that list the only con as "it doesn't stop."

My singlespeed commuter has a beefy Surly Instigator fork. Straight, thick steel. I don't feel any difference in comfort compared to my road bike, which has a thin, curved steel fork.

And the dishing is a minor problem. In fact, for a rear wheel, there would be LESS dish, although the flange-to-flange distance would be shorter.

You can't be serious!? Do you actually believe what you just wrote? Lights and reflectors are OUTSTANDING for making a cyclist visible to other traffic. Either one on its own would not be as good as half of both combined.

Lights make cyclists visible. Reflectors work at small ranges of angles. When I see a cyclist at night with no lights I identify his shirt long before his reflectors (unless he's wearing a black or blue).

I never said anything bad about lights. I apologize if my grammar was misleading.

You can lock your front wheel? How do you lock it without the rear wheel coming up? I have done many panic stops and have even tried to lock the front wheel... all I've ever been able to do is a stoppie.

You decrease pressure when it locks. It's called modulating I do believe. Disc brakes supposedly do it for you, although I don't understand how.

I generally try not to lock my front brake, but it has briefly happened.

Edit: Also, it's usually late in the stop, and by this time my back wheel is 30 degrees out. I hate those stops. Stupid dog handlers (I like the dogs).

What I mean is, my front wheel doesn't lock at all. Ever. On any one of my 7 bikes. And I hope it never does.

In that case, your area lacks decent reflectors.

Reflectors available here are generally highly visible within a 140 to 160-degree sector. Lights, on the other hand, are often weak LEDs that are barely discernable in anything but unlit roads outside urban areas.

Lights are good for those cases where the other vehicle doesn't have a light pointed in your direction, but that's rarely the case in the real world.