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  1. #1
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    BB7's: No Stopping Power?

    I've been running BB7's for a couple years now and I finally got fed up with not being able to lock out my back wheel. No matter how much adjusting I do, the rear brake doesn't stop worth a damn. I decided to get bigger rotors (203/185) to see if that would help. The front stops on a dime, but if I were to just use the rear brake, it barely stops me. Ideas? I don't like the idea of relying on my front brake if I need to stop short.

  2. #2
    g3h6o3
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    Quote Originally Posted by 99SX
    I don't like the idea of relying on my front brake if I need to stop short.
    And you think locking your rear brake will make you stop faster? Rely on your front brake for a short stop.

    So I gues you have 6 inch rotors front & back right now, is that it? That's what I have and can lock both brakes with 1 finger very easily. I weight around 160, how much do you weight?
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  3. #3
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    1st off, you need to get comfortable using your front brake because that is where most of your stopping power is.
    That said, a BB7 is plenty capable of locking up your back wheel. My guess is either your pads are glazed, contaminated, or you have crappy cables (does it feel spongy when you grab your brake?).
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  4. #4
    R.I.P. DogFriend
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    You're saying the rear wheel just keeps spinning no mmatter how hard you pull on the lever?

    Definitely not right.

    Take out your pads, knock the glaze off of them by putting some sand/emory paper on a flat surface and lightly rub the braking surface on it. Spray the pad with a couple squirts of brake cleaner. Clean the rotor with either brake cleaner or rubbing alcohol. Bed the pad back in gradually and see if the stopping power is better.

    I wouldn't put a larger rotor on the rear than you have on the front. In a properly working system, it would actually be better to have a larger rotor in front. You should be able to skid the rear tire pretty easily with a properly working system (not that it's the proper way to stop quickly).

    Quote Originally Posted by trailville
    My guess is either your pads are glazed, contaminated, or you have crappy cables (does it feel spongy when you grab your brake?).

    Good call, check the cables AND housings out too!

  5. #5
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    Quote Originally Posted by PissedOffCil
    And you think locking your rear brake will make you stop faster? Rely on your front brake for a short stop.

    So I gues you have 6 inch rotors front & back right now, is that it? That's what I have and can lock both brakes with 1 finger very easily. I weight around 160, how much do you weight?
    I weigh right around 200. I have the the 8 inch rotor up front and 6 inches in the back. The lever doesn't feel spongy, it actually feels pretty solid until it really start squeezing it and at full force I just gradually slow down. That's just using the rear brake only. I'm running Jagwire cables and so far so good. I could try cleaning them.

    As for trying to skid...I never because its a big fat no no on the trails, especially out here. But it would be nice to be able to lock up my back wheel with no problem. hmmmmmmmmmmmmmmmmmmmmmmm

  6. #6
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    you absolutely should be able to lock up the rear.. you should be able to lock up the rear really easily actually.

    im also 200lbs, also on a 6 inch rear rotor. that thing should lock easy.

  7. #7
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    Based on that feel, it sounds exactly like what happened when I got oil on the rear rotor. Any black gunk on the rotor? Definitely pull the pads, heat them with a heat gun or something until they mostly stop smoking, sand them lightly, clean the rotors and bed them in like new brakes.

    Also, your front brake is 80% of your stopping power. Rear brakes are used for some maneuvering (tightening up in a turn, other times when it's unsafe to use the front brake).

  8. #8
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    I am just going to get BB7's on my hardrock(185/160). I used to have shimano 415's and apearently the pads were contaminated and that resulted in no stopping power at all. Does anybody know how the pads can get contaminated?
    Thanks.

  9. #9
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    Quote Originally Posted by Jeremy3
    I am just going to get BB7's on my hardrock(185/160). I used to have shimano 415's and apearently the pads were contaminated and that resulted in no stopping power at all. Does anybody know how the pads can get contaminated?
    Thanks.
    Pads get contaminated when you get oil on them or on the rotor. Be careful when applying lube to your bike, don't touch the rotors with your fingers (you leave oil from your skin on the rotors).

  10. #10
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    Oh. Thankyou, I think I might have done that or someone else did.

  11. #11
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    Sounds like a cable setup/adjust problem.

    When you initially set up the cable length there should be a small amount of slack in the cable. The levers of the BB7 calipers always needs to return completely extended without any limit from cable tension when the hand levers are released. You can use the hand levers' barrel adjusters initially to fine tune the minimal cable slack. This specified cable slack set up produces the powerful leverage angle when the brakes are applied.

    After initial set up with minimal cable slack, NEVER adjust the brakes closer to the rotor by tightening the cables. Doing so reduces the leverage and power is reduced a lot.

    Only use the red knobs to adjust the pads closer to the rotor. It's a pain but it usually has to be done every couple rides front and rear to keep the hand levers from getting too close to the handlebar.

    Those red knobs can be removed for maintenance, just pull them off, and the screws they turn can be maintained carefully with a drop of lube if needed to turn easily. Be sure to not drip any lube near or on the pads or the pads will fail to work well.

    There are more powerful hydraulic systems now but the BB7's with good pads are very progressive, modulate well, and powerful enough to lock up easily when set up correctly with cable slack and adjusted close to the rotor only with the red knobs.

  12. #12
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    It sounds like it could just be a contamination problem. I'll clean the rotors and pads and see if that works.

  13. #13
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    Quote Originally Posted by derby
    Sounds like a cable setup/adjust problem.

    When you initially set up the cable length there should be a small amount of slack in the cable. The levers of the BB7 calipers always needs to return completely extended without any limit from cable tension when the hand levers are released. You can use the hand levers' barrel adjusters initially to fine tune the minimal cable slack. This specified cable slack set up produces the powerful leverage angle when the brakes are applied.

    After initial set up with minimal cable slack, NEVER adjust the brakes closer to the rotor by tightening the cables. Doing so reduces the leverage and power is reduced a lot.

    Only use the red knobs to adjust the pads closer to the rotor. It's a pain but it usually has to be done every couple rides front and rear to keep the hand levers from getting too close to the handlebar.

    Those red knobs can be removed for maintenance, just pull them off, and the screws they turn can be maintained carefully with a drop of lube if needed to turn easily. Be sure to not drip any lube near or on the pads or the pads will fail to work well.

    There are more powerful hydraulic systems now but the BB7's with good pads are very progressive, modulate well, and powerful enough to lock up easily when set up correctly with cable slack and adjusted close to the rotor only with the red knobs.
    This is something I've thought of but never seen written before now. I'm glad to hear it, makes me feel like I'm on to something. I adjusted mine so that it's getting maximum leverage from the "arm" on the caliper right as the brakes engage.

  14. #14
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    Quote Originally Posted by BuickGN
    This is something I've thought of but never seen written before now. I'm glad to hear it, makes me feel like I'm on to something. I adjusted mine so that it's getting maximum leverage from the "arm" on the caliper right as the brakes engage.
    Yes, the pads should engage the rotor when the caliper's lever arm rotates to near 90 degrees, but not past 90 degrees, to the cable. This brings the best modulation and most power. When I ran those brakes there was a little slack in the cable when released to obtain that most powerful mechanical leverage.


    Another problem could be worn cable housings or frayed cables which would cause more friction and binding.

    I doubt if he has a pad problem, but it's possible. Swap the pads front to rear to test that without spending money.

  15. #15
    Mr. Shibing
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    I'm having a set of bb7 on mine now.
    Front 185 mm, back 160 mm. I weight about 155 lbs. I certainly feel the braking power for a short distance is from the front.
    In a very short brake, my rear would lock up a little bit due to my adjusting and my weight is not totally put at the back, but i do not feel it's safe because it may cause you slide.

    By changing the brakes, I always make sure the cables are good or I will just change them. Since I ride in snow in the winter, and rainy days, plus the freezing rain in the winter, I just get the JagWire cords, which will have less troubles of rust inside of the plastic tube. I'm a college student who don't have a car, and I live about 2 miles away from school. You can probably image.

    Well, it's just what's on my mind. I would say your problem may come from either cable or adjusting of the calipers. Plus the disk brakes should not lock the wheels even in extreme braking conditions.(I forgot where I heard befire) Which can be a safer solution for all condition riding.
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  16. #16
    ballbuster
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    ^^^ what he said ^^^^

    Quote Originally Posted by derby
    Sounds like a cable setup/adjust problem.

    When you initially set up the cable length there should be a small amount of slack in the cable. The levers of the BB7 calipers always needs to return completely extended without any limit from cable tension when the hand levers are released. You can use the hand levers' barrel adjusters initially to fine tune the minimal cable slack. This specified cable slack set up produces the powerful leverage angle when the brakes are applied.

    After initial set up with minimal cable slack, NEVER adjust the brakes closer to the rotor by tightening the cables. Doing so reduces the leverage and power is reduced a lot.

    Only use the red knobs to adjust the pads closer to the rotor. It's a pain but it usually has to be done every couple rides front and rear to keep the hand levers from getting too close to the handlebar.



    Those red knobs can be removed for maintenance, just pull them off, and the screws they turn can be maintained carefully with a drop of lube if needed to turn easily. Be sure to not drip any lube near or on the pads or the pads will fail to work well.

    There are more powerful hydraulic systems now but the BB7's with good pads are very progressive, modulate well, and powerful enough to lock up easily when set up correctly with cable slack and adjusted close to the rotor only with the red knobs.
    Do not use the cable barrel adjusters to adjust the pad contact point. Use the red knobs.

    I would say I see more BB7s adjusted improperly with this issue than ones that are actually adjusted properly.

    What happens is you crank down on the bar lever, and the actuator arm on the brake hits the body before it can fully bite down on the rotor, limiting its power.

    Also, on a side note.... be sure to trim that extra bit of cable so it is short enough not to reach the rotor. I have a bud who;s BB7 ate the bit of cable, and whuped his brake and rotor up real good. He's lucky he didn't crash. He had total brake failure when his rotor sucked in the cable. IIRC, there was an Avid service bulletin on this issue.

  17. #17
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    Quote Originally Posted by kuratsunade
    I'm having a set of bb7 on mine now.
    ... I ride in snow in the winter, and rainy days, plus the freezing rain in the winter, I just get the JagWire cords, which will have less troubles of rust inside of the plastic tube.
    That will help.

    Also less expensive to keep water and dirt out of cables is to run continuous cable housing. You can drill out the cable guide stops for a clean finished look, or wire the housings outside the guides, or use these to route the housings: http://www.jensonusa.com/store/produ...ne+Guides.aspx

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