GXP Bottom bracket spacer question

Stellite
Stellite Posts: 544
edited March 2011 in Workshop
My bottom bracket shell measures 70mm.
Im fitting an SRAM force groupset, and it indicates 73mm shell requires no shims, and a 68mm shell requires 2 x 2.5mm shims.

Take it I have to source 2 x 1.5mm shims and fit these to equate to the 73mm.

No sure why the frame is machined to 70mm if it causes all this hastle.

Comments

  • salsarider79
    salsarider79 Posts: 828
    It will be 68mm. I can say with 99.9% certainity.

    If it is 70mm then 1 x 2.5mm shim will be fine.

    If your fitting such a quaility groupset, why not get the BB faced first?
    jedster wrote:
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    FCN 3 or 4 on road depending on clothing
    FCN 8 off road because I'm too old to go racing around.
  • Stellite
    Stellite Posts: 544
    Ive checked the size with my vernier so its correct.

    Its a titanium frame, so I thought facing this would be a bit of a problem,

    Would it be better fitting a 2.5mm spacer on the drive side, or 2 x 1.5mm spacers, one either side.
  • rake
    rake Posts: 3,204
    Stellite wrote:
    Ive checked the size with my vernier so its correct.

    Its a titanium frame, so I thought facing this would be a bit of a problem,

    Would it be better fitting a 2.5mm spacer on the drive side, or 2 x 1.5mm spacers, one either side.
    depends on the chainline. if you get i faced they could probably take it down to 68mm, that may be why its a bit bigger.
  • synchronicity
    synchronicity Posts: 1,415
    Are you 100% sure it's not an Italian threaded BB? They measure 70mm wide. :wink:
    vertebr.ae | precision braking & shifting
  • Stellite
    Stellite Posts: 544
    Aye its definately English thread, ive got the cups screwed in finger tight at the mo
  • Monty Dog
    Monty Dog Posts: 20,614
    I would mount the spacers to suit the chainline.
    Make mine an Italian, with Campagnolo on the side..
  • bradz72
    bradz72 Posts: 3
    I have had problems installing a sram force crank on my frame the BB came with no spacers but am having the BB faced to 70mm.Will i need spacers ?

    Cheers
  • bradz72
    bradz72 Posts: 3
    Forgot to say its italian thread
  • rake
    rake Posts: 3,204
    the spacers have no effect on the pre load. so its just down to chainline really.

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