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  1. #1
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    2012 giant xtc 29er 2 bottom bracket

    ok guys i need some help. I have a 2012 giant xtc 29er 2. It has a bb91 bottom bracket. Im switching out the crank to a shimano xt m785. Im curious if the shimano bb91 is the only bottom bracket that will fit. Id like to use a different brand but shimano is the only bb91 I can find. Any input would be great.

  2. #2
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    I'm pretty sure your bike has a BB92 shell. BB91 is the series number that Shimano assigned to that design (like m785 for cranks). If you measure the bottom bracket shell width you can confirm this.

    Assuming it is a BB92, you can use any BB92 bottom bracket of your choosing.

  3. #3
    Rub it............
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    Here is a good article about Shimano's Press Fit BB's.

    BB91 and BB92 are the same thing regarding Shimano's PressFit bottom brackets.

    Park Tool Co. ParkTool Blog BB90, BB86, BB92, Press Fit Bottom Bracket Service

    Shimano BB92 Bottom Bracket | Competitive Cyclist

    That being said, you need to make sure that the bottom bracket you pick is compatible with the crank that you have.

    Shimano and Race Face will work with your Shimano crank, but a Sram will not due to the tapered spindle. A Shimano and Race face crank spindle is 24mm in diameter. Sram has a 24mm diameter spindle on the drive side, but it's 22mm on the non-drive side.

    Just buy the Shimano BB91(92) bottom bracket.

  4. #4
    DDG
    DDG is offline
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    Just curious, on my 2011 XtC 2, it has a threaded bottom bracket (Shimano External). Did they change this for 2012?

    I need to replace mine, and the LBS den't have it in stock.

  5. #5
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    Giant did change the bb in 2012. Your shop can order a bb or you can get other aftermarket bb's like Chris King, Race Face, Hope and others. Or it is also possible with the right tools to replace the bearings.

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