tcfh

Hi,

I have a problem with my rear mechanical disc brakes on my hybrid bike. Every time I press the brakes, it works, but the cable doesn't seem to retract to its original position and remains squeezing the disc brakes even though I release the brake level. I'd have to manually pull the caliper back to its original position to stop braking. Would this be a cable issue? I have never lubed my cable since I got my bike (had it for 6 months and practically used it everyday biking in the rain and snow).

One thing I notice, when I bring it indoors, the rear brakes work fine. Outside is -7˚C.

Summary:
1. Squeeze and hold on rear brake lever
2. It is a little stiff and difficult pulling the lever
3. Rear braking occurs
4. Release brake lever
5. Brakes still remain braking on the disc brakes (rear brake cable not relaxing)
6. Have to manually pull the rear brake caliper to release cable tension and stop brakes from squeezing

Any tips on how to fix this problem?

Thanks!

Retro Grouch 

Check your cable housing ends. It's easy during the cutting process to leave a little burr that obstructs the cable. The easiest way to get rid of the burr is with a fine file.

Andrew R Stewart 

The obvious possibility is the brake cable is freezing in the casing. If this is the case the fix is to make sure the inner cable is rust/corrosion free, is smooth on it's surface and is lubricated in any casing. Expect the problem to return in time, moisture and cold temps. Even if the cable isn't freezing in place from water it's good practice to maintain one's bike. Andy

wschruba

If it's freezing, get a bottle of lock de-icer. Since it clearly moves both ways, you can force the water out that way.

dabac

Does your bike have the caliper mounted on the chainstay?
For mech brakes, that leaves the end of the outer cable angled up, not a terribly bright idea, as it tends to accumulate water.
One can try to seal it off using the rubber boot found on v-brakes.
Or use a Travel Agent to change direction and run the cable along top tube/seat stay instead.
A more industrious option is to mount a pulley and a cable stop on the chainstay, to let the outer cable end horizontally instead of at an upward angle.

dsbrantjr

With six months' of riding in rain and snow with zero maintenance, I think it would be fair to say that replacing the cable and housing with good quality lined housing and die-drawn stainless cables would be a good first step. Since the level of effort is identical and the cost low I just toss them rather than trying to clean/lube them.

JonathanGennick 

Everything works good in the warm? That would suggest some moisture in the cable that freezes when outside.

I favor dsbrantjr's suggestion. Sometimes OEM cables aren't exactly top shelf.

FWIW, I just replaced a friend's shifter cable using two weeks ago for the same problem. He rides in snow a lot, and as a result does tend to have to clean and replace parts more often than if he rode only in good weather.