can a knackered BB make cranks feel like they have a wobble?

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  • can a knackered BB make cranks feel like they have a wobble?
  • andymac
    Member

    I certainly have had crank wobbles with worn external bottom brackets, not used a GPX though. In fact just had to send an isis bracket back because it caused a wobble when new!

    Premier Icon midlifecrashes
    Subscriber

    Could it be the pedal?

    Premier Icon tmb467
    Subscriber

    Check that the pedal isn’t starting to come lose first

    That ‘wobble’ can be more pronounced when using a square taper BB but I’ve also felt it if the pedal loosens or the pedal thread starts to go.

    Other explanations are also possible!

    Premier Icon unklehomered
    Subscriber

    Pedals are firm, and pretty new. Will double check but pretty confident on that.

    That’s what it feels a bit like, I knew I’d felt it before, it feels like a slightly loose square taper…

    Premier Icon krixmeister
    Subscriber

    I would normally go with the pedals with this description (as with other comments above), especially if you can’t recreate unless you are pedaling. If you are using SPDs or similar, maybe a worn cleat? Also, unlikely but worth a check – make sure chainring bolts are nice and tight.

    Premier Icon unklehomered
    Subscriber

    Stuck at work and it could be a couple of days before I can swap the BB and see for myself. I know the non drive side was fitted with the spacer off set for a while 😳 , so not doing its job evenly around the cup, the non-drive side feels like it wobbles just after its passed 12 o’clock, only slight, and I can’t recreate unless peddling. GXP BB too, so blaming BB seems a place to start. Am I kidding myself?

    Would prefer not to be buying new cranks just yet, as the bike has a question mark over its future. Your pearls of wisdom or scorning criticisms over slapdash BB fitting are awaited…

    Premier Icon unklehomered
    Subscriber

    Thank guys, will check all this tonight, and give BB swap a go when I get the chance! fingers crossed.

    Premier Icon craig5
    Subscriber

    What cranks are you using? Had the same issue 2 week ago. I thought it was my pedals, I knew the bearings were shot. After 100m it was getting worse & on closer inspection found out my crank had come lose very very slightly on the drive side axle. Race face cranks attach to the axle on the drive side and the movement has mashed ( only slightly) the splines inside the drive side of the crank. Now my crank is a write off, as no amount of tightening will stop the wobble and it will only get worse with every pedal stroke. I’m gutted

    Premier Icon unklehomered
    Subscriber

    Its external GXP BB cups, but the spline issue you describe is my fear. Here’s hoping its something else or one of the things suggested above.

    Premier Icon Pridds
    Subscriber

    With Gxp cranks you tighten them onto the non driveside bearing ( essentially sandwiching the bearing between the step in the axle and the non driveside crank) so if that bearing is on its way out it might cause a wobble

    Premier Icon unklehomered
    Subscriber

    Well I had a bit more time than I expected, its the cranks, even my powers of self delusion and denial can’t hide that fact… I knew it in my heart.

    Premier Icon iain1775
    Subscriber

    I had exactly the same as you describe on my CX bike
    It was the GXP BB

    andrewh
    Member

    1. Check all bolts are tight and pedals screwed in firmly.
    2. Grasp both cranks firmly and try to wiggle them. If they move togther in a uniform manner it’s the BB. If one moves it’s the crank. If neither moves check the pedals. Note loose BB feels very similar to knackered BB.
    From your description (one crank and only when peddaling) I suspect BB/crank interface.

    Premier Icon unklehomered
    Subscriber

    See you’re just trying to get my hopes up. I may one last fiddle, but its not the BB, I’ve swapped it out for a spare. Even found myself checking the frame in case BB shall cracked, cos that would be better ❓ – I’ve more or less decided to replace the summer season with a BFe no anyway, so wouldn’t mind getting some cranks as part of that operation really.

Viewing 14 posts - 1 through 14 (of 14 total)

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