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  1. #1
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    SRAM GXP crank width problem

    I have this SRAM GX crankset and GXP bottom bracket. When I put it on the bike (68mm bb shell), it ends up too wide.

    SRAM GXP crank width problem-dsc05747.jpgSRAM GXP crank width problem-dsc05748.jpgSRAM GXP crank width problem-dsc05749.jpg

    I took it off and assembled it on its own. With the two spacers included, it ends up at approx 72mm.

    SRAM GXP crank width problem-dsc05755.jpg

    So I figure it needs another two spacers to reach 68mm, but that just doesn't make sense. The numbers don't even add up perfectly.

    If anyone could shed any light on this, it would be greatly appreciated.

    I have another NX crankset and a similar bb as mentioned with the same problem. I have not found any docs at SRAM indicating the use of more than two spacers to fit 68mm.

    Help..

  2. #2
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    You have everything you need to install it. If the BB is 73mm then you use no spacers. If you have a 68mm BB (like you do) then you use one spacer on each cup. Have you actually installed this on the bike and had problems? If so, you are doing something wrong. As far as the last picture with the ruler, unless you have properly torqued the arm down (I think its like 55nm) then you are going to get a larger measurement.
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  3. #3
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    No. I've been through all the regular did-you-plug-in-the-power-chord type things. I'm strongly doubt I've done anything wrong here. Arm is torqued hard.

    I found this earlier post:

    PLEASE HELP!!! XX Crank (GXP) in a 68mm shell - spacer problem

  4. #4
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    Remember, a GXP crank doesn't float. If you assemble it and the chainline is correct, you're good. Spindle width is more or less immaterial.

  5. #5
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    Quote Originally Posted by nrwgnBlue View Post
    No. I've been through all the regular did-you-plug-in-the-power-chord type things. I'm strongly doubt I've done anything wrong here. Arm is torqued hard.

    I found this earlier post:

    PLEASE HELP!!! XX Crank (GXP) in a 68mm shell - spacer problem
    Not to be a jerk, but installing an SRAM crank is not rocket science. Just install it with the two spacers, torque it properly and go ride. What exactly is it that makes you feel that this does not work on your bike?
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  6. #6
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    Right. A gxp spindle is laterally located by the step in the spindle and the NDS inner race. The step and left crank arm tighten against the NDS inner race. It doesn't matter if there is a gap on the DS as far as the BB is concerned.
    Do the math.

  7. #7
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    Lone Rager is correct. An SRAM BB doesn't use side loading on the drive side bearing, so no contact needs to be made on the drive side. From the SRAM website:

    GXP is different — and better. Other systems rely on side-loaded bearings to eliminate play, causing bearing wear. GXP captures the left-side bearing between the spindle and the left crankarm and allows the drive-side bearing to float axially on the spindle. There's no need to side-load bearings during adjustment. No excess wear. And a much simpler installation. Just tighten to the proper specifications and you're ready to roll, worry-free.
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  8. #8
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    Thanks for the replies. I don't mean to be rude either, but so far the comments seem to suggest I am incapable of rotating a hex wrench until it stops. I don't think it's that simple.

  9. #9
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    OK, so it seems I'm wrong and you guys are right: There is a gap on the drive-side between the crank arm and bb cup which supposedly is normal. Strange design. I'll try putting it on the bike again. Thanks.
    Last edited by nrwgnBlue; 6 Days Ago at 11:52 PM.

  10. #10
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    Many other designs require varying numbers of spacers under the arms or BB halves, wavy washers on one side or the other, finger tightened plastic preload screws or rings, etc,. to laterally locate the crank. By comparison to them, one that doesn't is indeed strange.
    Do the math.

  11. #11
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    I contacted SRAM and got a pretty detailed reply confirming that the drive-side gap is normal. Always a positive surprise when you actually get proper support.

  12. #12
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    Not sure if this is good advice or not but I converted a 3x xt crank to have a 32t ring. On my 68mm BB I had no spacers on the drive side and 2 on the other side. The chainline and shifting are near perfect now.

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