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Context:

I have a commuter/crossover bike with disc brakes, and a daily commute of ~20km. I upgraded to a bike with disc brakes after standard caliper brakes kept losing their stick and requiring pad replacements, as my rims became coated with oil from the roads (I commute past a diesel truck depot, and the road is nasty for about 1km).

Problem:

Since I upgraded, I have the opposite problem: literally every day in the winter, my disc brakes get full of mud, road salt, and sand. That stuff gets on top of and behind the (magnetically attached) brake pads, and makes them drag on the rotor. At best, they make the brakes constantly pull as if they were about 1/2 engaged. At worst, the water in the mud freezes and expands over night (I have a tiny apartment, and the bike sleeps outside), and the brakes are completely locked in the morning.

What I've Tried:

At first I thought it was the cables that were freezing with tension on the brakes, but after replacing and oiling them, I isolated the problem to the brake rotors/pads themselves.

The roads where I live are pretty much always covered in debris all winter, so changing my commute to avoid that stuff doesn't really work.

I've tried adjusting the brake pads farther away from the rotors. This works a little, but to fully prevent sticking, I have to adjust the pads so far out that I can't fully engage the brakes when I want to.

Up until now, I've been washing the bike with water every night (annoying, since during the winter the outside faucets don't work), and rinsing the brakes with warm water every morning to unfreeze them.

Question:

This is getting really old, so my question is: without obsessively cleaning them 1-2 times a day, how do I keep my disc brakes from getting gummed up? If the answer is "buy better disc brakes", that's fine. I just have no idea what to look for.

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That is very interesting question! What kind of brakes do you have? Never encountered that kind of problem with disk brakes. –  trailmax Feb 6 '13 at 15:32
    
I'm really not sure, honestly; whatever ships stock with a Trek 8.3 DS from 2012. –  Zac B Feb 6 '13 at 19:02
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evanscycles.com/products/trek/… says you have "Tektro Novela mechanical disc brakes" which are cheap and nasty breaks. I'd strongly recommend replacing them if they cause you a headache. –  trailmax Feb 7 '13 at 12:07
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2 Answers 2

I think that cleaning with water is the problem. You wash them overnight, leave the bike outside. Water freezes inside of the breaks. You splash hot water again in the morning and get more water on your breaks and behind the pads that will freeze later on.

I would try avoid using water in your daily clean. Just try it for couple times. Clean the pads with dry cloth and make sure there is no water in the system. And see how it works next day.

To be honest, I have never experienced this kind of problem. And I've used disk brakes for the last 10 years in very different conditions, including thin wet mud all over the bike, brakes and pads. And I never got mud between pistons and break pads. So I think the problem with "magnetically held" pads. My pads always been held in place by a spring.

So if you have this option, try changing the breaks, but make sure that new breaks hold the pads with a spring, not magnets.

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Just to add another point why debris or dirt seem to be not a good reason for your problems: as the rotor of the disc brake is placed at the center of the wheel, it should net get much dirt. I ride a MTB with disc brakes myself and even if the whole bike is covered with dirt, the only dirt that you can see at the brake rotor is the wear debris. So if there is not rivers of dirty water running down your fork and frame I wouldn't think that debris is the major reason. –  Benedikt Bauer Feb 6 '13 at 20:00
    
What he said ^^^! The major point of disk breaks is that they get less crap on them because they are further away from the surface. –  trailmax Feb 7 '13 at 12:10
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I think you need to find a balance between pad clearance and also the lever configuration. You haven't mentioned what brakes that you have or what levers. For example, Avid BB5's only have one adjustment knob, whereas BB7's allow pad adjustment on both sides of the disc. This can make a huge difference in the flexibility of your setup (BB7's being much better in this regard). The other variable is levers. Standard brake levers might have little control, but an Avid SpeedDial7 (SD7) lever, for example, gives you control over reach and leverage with adjusters right on the brake lever. This could allow you to maintain pad clearance but also give you the stopping power that you want while keeping pads further out.

Last variable in all this are your cables. Have you lubed the cables to keep them moving freely? Are you running full length housing to keep dirt and gunk out? Some cable have the option of having little rubber sheaths at the ends to keep grime from getting pulled into the housing. Compressionless housing (like Jagwire ripcord) will also improve disc brake performance on mechanical systems.

Hope this helps.

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