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  1. #1
    mtbr member
    Reputation: bega_ilidza's Avatar
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    BB Crankset compatibility

    Is there website or something where I can check compatibility between BB and cranks. In this particular case I would like to know what cranks I can use with DEORE XT BB-UN53.
    Thank you.

    Edit:
    Would any Shimano XT cranks work?
    Last edited by bega_ilidza; 12-04-2010 at 02:03 PM.

  2. #2
    Rub it............
    Reputation: frdfandc's Avatar
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    Since the bottom bracket you mentioned is square taper, you will need to find a square taper compatible crank set. The newer XT models use an external bearing bottom bracket and are not compatible with the square taper.

  3. #3
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    Thank you, does that mean that all square taper BBs support all sq taper compatible cranksets and all external bearing BBs support all external bearing compatible cranksets.

  4. #4
    Fat-tired Roadie
    Reputation: AndrwSwitch's Avatar
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    Sort of, and nope.

    Buying a crank to match a bottom bracket is a little bit of putting the cart before the horse. Bottom brackets are relatively inexpensive items and wear out - I think of them as being similar to a chain or a cassette. Cranks that attach to a bottom bracket, whether it's a square taper cartridge bottom bracket like yours or another standard, usually list a spindle length they're compatible with. You HAVE to get a square taper crank. If you get a new crank designed for a longer spindle than the bottom bracket you already have, it will probably install but you may have clearance issues and you'll probably have chainline issues. If you get one designed for a shorter spindle, it'll install and clear fine, but probably have chainline issues.

    There are a few different external BB sizes, but getting it right is a little easier IMO, unless you get FSA stuff. For the most part, just match brands. Shimano claims that they're road and mountain cranks and bottom brackets are not interchangeable, but I haven't had a problem interchanging them. Many brands claim to be compatible with Shimano - that information would be on the web site or in the catalog.

    parktool.com has some pretty good discussions and pictures of a lot of this stuff, so you can get a better idea of why certain combinations are and are not compatible.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  5. #5
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    Thanks a lot. Reading more about these standards I came across this
    WEBSITE
    Very useful

  6. #6
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    Shimano Road and Mountain BB's are NOT interchangeable (per the official Shimano party line. The road BBs are wider than the MTN BB's). Buy the crank that you want and the corresponding BB will be cheap/easy to find. One word of caution: Sram/Truvativ GXP cranks are not compatible with Shimano/FSA cranks, the bottom brackets have different bearing setups on the non-drive side. This also creates a scenario where if you want to overhaul a BB with new bearings, it's easier with Shimano because you can simply replace the bearings. With Sram you need to buy a shim for the non-drive side because they use a special asymmetrical bearing.

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