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  1. #1
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    New question here. disc brake cable tension advice needed

    Im running front and rear avid bbdb 5 mechanical discs.

    I've decided to do the install myself and everything is cool, but the cable tension seems off.

    Initially I could pull the levers all the way to the handles, which I knew was a problem, so I went back, pulled the cable tight at the disc anchor, and then fine tuned with the cable adjust at the lever. However the cable adjust is now backed pretty far from the lever.
    I get a nice firm pull now, with the lever taught about halfway to my grip, and the discs bite hard with good modulation, but I don't have much room to adjust for any future cable stretch and it makes me nervous having the the adjusters so far out. They seem pretty solid, but they are more then halfway out there.

    Any thoughts . . .


    lom

  2. #2
    nnn
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    You could loosen the retaining bolt on the caliper slightly so the cable only moves if you pull it with a tool then twist the barrel adjuster back and take off a little bit of slack from the caliper side so you don't overdo it. Maybe you could also attach the cable while squeezing the caliper arm slightly(with hands), then the spring return should take up some extra slack.

  3. #3
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    Quote Originally Posted by nnn
    You could loosen the retaining bolt on the caliper slightly so the cable only moves if you pull it with a tool then twist the barrel adjuster back and take off a little bit of slack from the caliper side so you don't overdo it. Maybe you could also attach the cable while squeezing the caliper arm slightly(with hands), then the spring return should take up some extra slack.
    this is exactly how I did the setup:

    1. screwed the barrel adjuster at the lever all the way down.
    2. loosed the bolt at the caliper
    3. with a small flat head wrench grabbed the brake cable and pulled while simultaneously pushing the caliper slightly through it's motion.
    4. while pulling hard on the cable, I then tightened the anchor bolt on the caliper.
    **. also- the cable housing is direct without kinks.

    after this the lever is very mushy without unscrewing the barrel adjuster at the lever pretty far. It seems I'm doing pretty much what you and others have suggested, but is it possible Im not pulling hard enough on the brake cable to create the initial tension?

    Is there a tip I can learn?

    thanks

  4. #4
    Unshaven Yak
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    Have you considered the adjustments of your pads? That is the other element. I run the inside pad as close the disc as possible without rubbing, then adjust the outer pad so it contacts the disc at the right point in the throw of the lever.

    Initial tension seems to be your issue though. With new pads (or close to new), I would unscrew the outer pad to the max, then screw the barrel at the lever almost (but not) all the way in, then adjust the cable attachment to the caliper so that you have good return tension all the way through the lever-throw, then adjust the outer pad so that it hits the disc in mid-throw of the lever. You can fine tune from there using the barrel adjuster at the lever, but it is just for the finest tuning for exact feel.

    When changing the cable attachment to the caliper, I tend to have it set up so that the leverarm of the caliper has just about 1/4 to 1/2 inch of throw left when it is engaged before contacting metal on metal between the arm & the other arm where the cable exits the housing. Screw in the outer brake pad until this is the engagement point at the caliper.

    That is on the older Avid BB's, I'm not sure if the BB-5's or 7's are any different (or if mine qualify as one of those models). Sorry if that sounds confusing or just doesn't work, but I'm so automatic at these things now that I have just developed a feel for it.

    If any one adjustment is in the extreme, things are not right & you should compensate by resetting that adjustment to where you think it should be & then messing with another that you suspect will have the same effect. I honestly think you probably don't have the arm on the caliper tense enough, it has a LOT of extra throw when the cable isn't bolted on in the right spot. Don't use the barrel adjuster at the lever for anything more than the finest tuning of lever feel.

  5. #5
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    ... and if we just ...

    [QUOTE]
    I run the inside pad as close the disc as possible without rubbing, then adjust the outer pad so it contacts the disc at the right point in the throw of the lever.

    When changing the cable attachment to the caliper, I tend to have it set up so that the leverarm of the caliper has just about 1/4 to 1/2 inch of throw left when it is engaged ...
    [QUOTE]


    great advice.

    I finally fixed the problem by following your suggestion of adjusting the throw of the caliper arm. I brought the arm up just until it brushed the disc and backed it off around 1/4 inch or so, just until it didn't rub. I only needed a simple, small tweak of the barrel adjuster after that to get the feel I wanted.

    thanks everyone

    -lo

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