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  1. #1
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    Avid BB7 - "Sticky" Lever & Can't Lock-up Rear Tire/Rotor

    I have a relatively new Civilian Luddite (rigid SS 29er) with Avid BB7 mechanical disc brakes. After approximately 4 trail rides, the next time I took it out, the rear brake was giving me trouble. Engaging the lever was not smooth. Best description would be sticky or not fluid.

    I've tried adjusting everything I know to do with the pad alignment, the position of the brake arm / cable, and the barrel adjuster, but no luck. The brake arm seems to work fine when disconnected from cable.

    And one more thing, when I get it adjusted as best I can, I can't lock the rear wheel. I can grab the front lever and can't physically push the bike and make the wheel turn, but when I do the same on the rear, no matter how hard I pull the lever, I can still push the bike and make the rear wheel and rotor turn through the pads.

    Any ideas? I'm clueless on my first bike with disc brakes.

  2. #2
    Just Ride
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    try turning in the pads on the rear one click at a time. But not to the point the pads rub when not using the brake. If they rub then back it off a click. The nice thing about BB7 is easily adjusted and tool free. So you could mess with em while on the trail. I have had to do that before. Due to installer error, i.e. I didn't adjust em right in the first place.
    SS ==> Nut up or Shut up!

  3. #3
    rebmem rbtm
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  4. #4
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    Thanks. Will check on that when I get home. Any chance it could be a cable problem? Maybe needs lube? It did get exposed to some heavy rain.

  5. #5
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by ply5013 View Post
    Thanks. Will check on that when I get home. Any chance it could be a cable problem? Maybe needs lube? It did get exposed to some heavy rain.
    I would say is most likely a cable problem.

    Any extra friction in the cable run greatly affects the performance.

    Make sure the housing ends are clean and square. No tight bends.
    I prefer full length housing and the most direct routing. Teflon coated cables without lube.
    mtbtires.com
    The trouble with common sense is it is no longer common

  6. #6
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    Any special tricks to cleaning the cable and housing? I guess that's the first place I'll be checking.

  7. #7
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by ply5013 View Post
    Any special tricks to cleaning the cable and housing? I guess that's the first place I'll be checking.
    By "clean" I mean the ends are free of burrs and the liner is not crimped. Nothing to restrict the free movement of the cable.

    If you have interrupted housing with housing stops on the frame, the cable can be hanging up on the stops and/or the ends of the housing. Can also be tight bends in the housing that increase friction.

    EDIT: I see that the Luddite uses full length housing. The routing on the website bike is a bit screwy. The housing could be smoother at the seat tube. Should skip the last guide on the seat stay. Puts too big a bend in the housing. Would have been better to have the guides on top of the stay rather than under it.
    mtbtires.com
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  8. #8
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    Shiggy - Thanks for going above and beyond and looking into that. I'm constantly amazed at how much knowledge there is on these forums.

  9. #9
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by ply5013 View Post
    Shiggy - Thanks for going above and beyond and looking into that. I'm constantly amazed at how much knowledge there is on these forums.
    Another thing to check:

    Do not tighten the zip ties in the guides too much. You can pinch the housing and bind the cable.
    mtbtires.com
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  10. #10
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    Do not tighten the zip ties in the guides too much. You can pinch the housing and bind the cable.

    Wha?? I never thought of that. Must check zipz!!

  11. #11
    rebmem rbtm
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    Are the ends of the cable housing properly seated in the brake lever, brake caliper and cable stops on the frame?

    Do all of ends of the cable housing have end caps/ferrules on them ?



    I can grab the front lever and can't physically push the bike and make the wheel turn, but when I do the same on the rear, no matter how hard I pull the lever, I can still push the bike and make the rear wheel and rotor turn through the pads
    It sounds like it might be something more then a cable problem.

    Have you had a good look at the pads ?
    Worn down pads or pads with no pad material left on them will have no stopping power.
    Riding in wet conditions where there's lots of sand/grit can wear certain types of pads down very quickly.


    Is the rotor warped ?
    If you adjust the pads so there is no rotor rub on a warped rotor the brake won't have much power.


    I've tried adjusting everything I know to do with the pad alignment, the position of the brake arm / cable, and the barrel adjuster, but no luck. The brake arm seems to work fine when disconnected from cable.
    The barrel adjuster on the brake lever should only used for taking up cable slack.
    The red adjuster knobs on either side of the caliper should be used adjusting the pads.

  12. #12
    Trail Tire TV on blogger
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    cable is probably the main issue,

    Guessing there is a thread unwound/broken somewhere in the middle. Pull the inner cable and inspect it.

    But also, if you can't lock up the brake it's often times oil or some other lube got on the rotor/pads.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  13. #13
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    Thanks for all the suggestions. Unfortunately I don't have time to investigate because of work and some personal stuff to take care of with family this weekend. I'll let everyone know the outcome when I figure it out.

  14. #14
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    Also try spraying WD40 through the housing when you have the cable out. I usually drop some lube into the housing too. The zip tie too tight is true, as is the post about bends that are too tight in the housing. Check that the housing is the right length.

    Also, did you break in the pads and rotor by doing 10 or so really hard stops?

    Tom

  15. #15
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    Disconnect the cable at the caliper, push it back and forth through the housing. It should move freely and smoothly. If it does, cable isn't the problem.

  16. #16
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    Update: Work schedule hasn't allowed me to investigate anymore. I live in a small town with a LBS that doesn't get much business, so I did us both a favor and dropped the bike off yesterday for them to work on. They have the same ideas as you guys. Will post the results...

  17. #17
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    One of the great things about BB7s is that if you can figure whats wrong with the cable/housing you can simply ditch it and get a new set for under $5

  18. #18
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    Alright guys, as most of you suspected,there verdict was a kinked cable. Not sure how it happened, but all is well now. Thanks for all the advise.

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