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  1. #1
    rmi
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    Having to tighten bottom bracket every 1-2 rides...Why?

    Hey all:

    So, my bottom bracket becomes loose again after every 1-2 rides (whether offroad riding or spirited road riding). I have a 2006 Trek hardtail and have never done any maintenance on the bottom bracket (sealed cartridge) since buying it, other than tightening it when it starts to pop/click/loosen.

    I should mention that I am tightening it down pretty good every time, although I am not using a torque wrench to make sure that I am tightening to spec.

    Any ideas what I should do next?

    Thanks- Ryan

  2. #2
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    I'd think you're not tightening the bottom bracket enough. Takes quite a bit of torque and while it doesn't necessarily take a torque wrench, what are you tightening it with? Is it the bottom bracket in the shell coming loose or just the crank arms? Are you completely removing the bottom bracket, cleaning and regreasing the threads before tightening?
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  3. #3
    rmi
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    The bottom bracket in the shell is coming loose. I made it a point to make sure that it just wasn't loose crank arms.

    I am tightening it with the special BB Park Tools tool, and a socket wrench that fits into the middle of the BB tool (I don't have a big enough wrench to fit over the outer hex of the tool). I am not babying it when I tighten it (and have a good idea of wrench torque through working on my motorcycle).

    The bottom bracket and threads have been greased once by me in 3 years, but never cleaned. Could some grit and gunk really contribute to this chronic "loosening"?

    Ryan

  4. #4
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    might wanna to replace the bb before it strips out the bb shell, this happened to my 2000 trek 6500,
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  5. #5
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    Quote Originally Posted by rmi
    The bottom bracket in the shell is coming loose. I made it a point to make sure that it just wasn't loose crank arms.

    I am tightening it with the special BB Park Tools tool, and a socket wrench that fits into the middle of the BB tool (I don't have a big enough wrench to fit over the outer hex of the tool). I am not babying it when I tighten it (and have a good idea of wrench torque through working on my motorcycle).

    The bottom bracket and threads have been greased once by me in 3 years, but never cleaned. Could some grit and gunk really contribute to this chronic "loosening"?

    Ryan
    From your description and timeline I'd think you should have removed the bb entirely a few times, at least I would have with every noise/loosening to inspect, if anything. For that much time involved with a single bike, or bike I'm riding most of the time, I'm doing a complete overhaul at least once annually anyways but I may be more into it than most and have the time/tools to do so. It's easy enough to clean and regrease while you go to the extent of taking off the cranks...

    I'm no thread expert but imagine contaminated threads may contribute to loosening if not thread damage. I always like to torque a fastener from install to the end at one go, rather than just add some tightening force to an installed one.

    How long a lever arm are you using? Might help to have an extender if you're using a short handled ratchet. Most cups should be tightened to a pretty high value, for example Shimano cartridges I believe are recommended in the range of 430-600 in lbs.
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  6. #6
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    Something sounds broken to me. The BB should not come loose repeatedly - unless it isn't tightened enough. And the assumption is that you do in fact tighten it sufficiently.

    I'd recommend taking the complete BB out and to give it a thorough cleaning and inspection. Something isn't right
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  7. #7
    rmi
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    Thanks for all the replies and advice. I am going to take time this week and completely remove my BB, inspect it, and clean/grease the area. If this doesn't solve the problem, I may invest in a new BB and see if that solves the problem.

    And I'll use my 16 inch "breaker bar" to tighten that damn thing instead of my socket wrench......and see if this does anything.

    Thanks- Ryan

  8. #8
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    You've got the right idea. Take it out, clean everything really really well, inspect all the threads, grease it all up and pop it back in.

    Bottom bracket loosening is pretty uncommon (usually they get stuck!) so it's definately worth having a good look.
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  9. #9
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    *Almost* not possible...

    Under normal conditions, a loosening bottom bracket is almost not possible. Your pedaling motion *generally* tightens it as you ride.

    You're on the right path based on the other posters' suggestions.

    I'd take a good hard look at the threads. It sure sounds like they're shot.

    Pictures would help.
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  10. #10
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    sounds like something is cracked. Nothing else I could think of would make it do that, outside of just not tightening it enough.

  11. #11
    rmi
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    So, after a couple weeks of riding, I think I solved my problem just by really tightening the BB (both sides). I think there was a couple of times where I thought I could get away with just tightening one side of the BB because I thought only one side was "loose." I now realize that this is not how BBs work.

    Anyway, thanks for the help all!

    Ryan

  12. #12
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    One thing comes to mind if you have to tighten it again:

    Tighten the drive side cup (fixed to the BB body) first. Get it all the way tight, then install and tighten the non drive.
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  13. #13
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    This is a good example of why torque wrenches should be used. Generally speaking, a person will over tighten a low torque part, and will not tighten a high torque part enough.

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