Help bottom bracket

Discussion in 'Cycling Equipment' started by bigkev, Oct 28, 2006.

  1. bigkev

    bigkev New Member

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    can anyone halp i have a giant boulder and i just smashed the bottom bracket its letting some bad grinding sounds what would be a better bottom bracket to replace it with a bit stronger the bike has only done 2000km . thanks
     
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  2. carbonguru

    carbonguru New Member

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    Is it an ISIS BB?:rolleyes:



     
  3. bigkev

    bigkev New Member

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    not shore i dont know my gear to well but it a standard one and told by the lbs its a cheap chinese one that come standard withe shamao cranks
    square ends i dont know if that helps.


     
  4. Retro Grouch

    Retro Grouch New Member

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    Bingo! Square ends is the exact bit of information that we need. If it was my bike I'd get a Shimano UN53 bottom bracket for it. At the low end lots of manufacturers cheat by using some pretty low end bottom brackets. The Shimano UN53 is a big step up in durability and is only a few dollars more expensive.
     
  5. bigkev

    bigkev New Member

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    is there one a lot stronger as i am a hard rider and 125 kgs i do stand on the pedals and av speed is 28 km and prob dont go down in low gears start in higher gears thanks



     
  6. bigkev

    bigkev New Member

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    i carnt seem to find un53 do you mean un25 i have checked the shamano website thanks



     
  7. nerdag

    nerdag New Member

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    What crankset are you using it with (double/triple)? I have a spare shimano BB-UN71 (105 grade, back in the day) that was pulled off an old road frame that was hardly used, before converting it to a trainer bike. Has boths ide of hte BB shell, and axle bolts too.

    Axle length is about 113mm (don't have calipers, so guesstimating from a ruler) - let me know if you're interested.

    n
     
  8. IEatRice4Dinner

    IEatRice4Dinner New Member

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    one note shimano is phaseing out square taper... it will get to be hard to get thay kinda stuff soon... stock up
     
  9. bigkev

    bigkev New Member

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    it is square it is a triple crank 113.5 wide the cranks are shamanio the chain guard has "dual sis index" on it nothing on the crank only brand thay are the ones that came with it any how oftern should the bottom bracket be changed.thanks



     
  10. nerdag

    nerdag New Member

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    I'd think the UN71 I have matches up in axle length with the one you have.

    Any idea on what your BB shell width is? That's probably the only other sticking point - this one is from a road bike with a 68mm english threaded shell. If yours is a little longer (eg. MTB shell of 72mm), then it may not work.

    You should replace them pretty much as soon as you start hearing signs of wear, like you're describing. How many kilometres this is depends on a whole lot of things.

    If you plan to keep your current bike for a few more years of lots of riding, it may be worth upgrading the whole crankset and BB to something that will be around for a while, like an ISIS setup or (if you have a lot of money to spend on a not so expensive bike) hollowtech. You could also upgrade to octolink, but that is being phased out as well.

    n
     
  11. Retro Grouch

    Retro Grouch New Member

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    Japanese spec square taper bottom brackets are one part that I don't anticipate being difficult to find for a long time.

    It's the high end stuff that disappears. 27 x 1 1/4 tires, which haven't been spec'ed on new bikes for probably 20 years, are easy to find but you can't get better-than-Sora quality 8-speed STI shifters.
     
  12. ralphcorrales

    ralphcorrales New Member

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