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  1. #1
    mtbr member
    Reputation: Yardstick's Avatar
    Join Date
    Jan 2007

    Sram/Truvativ GXP Bottom Bracket Engineering Fail

    I recently replaced my second Sram/Truvativ GXP bottom bracket because of play I could feel in the cranks. The first one was replaced under warranty. The bike shop couldn't figure out where the play was coming from. They could feel and see the play in the cranks with everything assembled. With the cranks disassembled, the bearings felt tight and smooth. They put it back together and the play was back again. They didn't do any further investigation and replaced the BB. Suddenly there was no more play! But why?

    A couple weeks ago I was riding a different bike with the same Truvativ GXP BB and felt that telltale play in the cranks again. This bike is out of warranty so I bought a new Truvativ GXP BB figuring it was the same issue and would require the same solution. Again, there was play in the cranks when assembled. There was no play in the bearings and the bearings felt fine when the cranks were disassembled. Put it all together with new grease and torque it down and there's play again. WTF?

    It turns out there's a plastic spacer on the drive side between the crank spindle and the bearing. It's there to take up the space between the two. So there's this piece of plastic with huge compressive loads on it sitting between two pieces of steel! Who's bright idea was that? Plastic, even really hard plastic, is very weak compared to steel. The plastic deforms relatively easily and eventually starts walking around causing even more wear. Eventually you feel it as play in the cranks.

    Is there an alternative to the Sram/Truvativ GXP bottom bracket that doesn't use a plastic spacer between the crank spindle and the drive-side bearing?

  2. #2
    ~ B A D A S S ~
    Reputation: car bone's Avatar
    Join Date
    Apr 2011
    I think both CK and enduro BBs are no plastic.
    Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.

    Quote Originally Posted by iheartbicycles View Post
    Specialized sucks ass.

  3. #3
    mtbr member
    Reputation: yourideit's Avatar
    Join Date
    Jan 2009
    i went through two gxp bottom brackets in two months and said no more. i put them in the toilet where they belong. i intalled a hope bb and have had zero issues. for the x0 crank i am using i did have to install a shim. easily pressed in with some blocks of wood and a bfh.
    "if you can't be good, be good at it."

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