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Crankset movement in BB

wackawacka Posts: 169
edited April 2019 in Workshop
Hi,

I've fitted a CeramicSpeed GXP Pressfit BB86 to my Giant TCR and when I installed my SRAM Red 22 GXP crankset, there seems to be lateral movement either side of the BB cups. I've installed both as per instructions with wave washer drive side and weather seal non-drive. I cannot tighten the left crank arm any further to secure the gab.

Any advice?

Cheers

Posts

  • whyamiherewhyamihere Posts: 7,438
    What are you using to tighten the crank arm? It needs 50Nm, which is a fair amount. If you're using a smallish hex key you probably haven't done it up tight enough.
  • MatthewfalleMatthewfalle Posts: 17,380
    50 is a lot - 10 more than a cassette lock ring.

    big ratchet with allen key on the end of or - infinitley preferable - the same big torque wrench you would use for your lock ring.
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • pilot_petepilot_pete Posts: 2,002
    Sounds like you are missing a spacer, it shouldn’t take 50nm to take up a gap...check the bottom bracket manufacturers 8nstallation instructions for your frame as the spacers/ washers usually vary from frame to frame...

    PP
  • It's counter productive to use a wave washer to take up slack as the washer creates pressure (friction) defeating the purpose of the so-called benefit of ceramic bearings. Instead use spacers to eliminate the play.
  • whyamiherewhyamihere Posts: 7,438
    It's counter productive to use a wave washer to take up slack as the washer creates pressure (friction) defeating the purpose of the so-called benefit of ceramic bearings. Instead use spacers to eliminate the play.
    Always nice to see people who claim to know more about bearings and BBs than companies like CeramicSpeed and Sram...

    Don't put any additional spacers in. Use what comes with the BB. Sram BB86 BBs also come with a dust cover for the NDS and a wave washer for the DS, but they do require a lot of torque to get rid of all the play.
  • sungodsungod Posts: 13,350
    c. 50 is the specified torque for gxp, it really is that high

    with gxp, the axle is free to float on the drive side, with just a wavy washer to keep a bearing shield in place

    on the non-drive side the step on the axle clamps to the inside of the inner race, on the outside the shield is clamped to it by the crank as it's tightened

    if there's side to side movement, the problem is on the nds

    a few things it might be...
    - not clamped tight to the inner race, i.e. not enough toque used (or if all else fails add a thin shim)
    - the pressfit cup is moving within the bb shell
    - the bearing is moving within the pressfit cup
    - there's slack in the bearing itself
    my bike - faster than god's and twice as shiny
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