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Can I adjust away a creak from a bottom bracket?

bucklbbucklb Posts: 296
edited May 2013 in The workshop
I've had an irritating creak/click from the driveset for a couple of weeks; it comes and goes. I've looked around the many forums for advice on diagnosis & likely causes. I'm absolutely sure it's not the pedals (as I've put a fresh set on today). It's not the chain wheel (as I get the crea with the chain off) and I also get the creak out of the saddle.

This bit from Sheldon's website seems to describe the problem - I get a likely sounding creak/click by following these steps.
Bottom Bracket Cups/Retaining Rings Loose?
Because of the threading of normal bottom brackets, the cups are self-tightening to a point. This sometimes leads to careless installation, particularly on the right (fixed cup) side. If the right cup is slightly loose, it won't necessarily unscrew itself, but it won't really tighten itself up fully either. The symptom of this is an occasional creak or clunk usually as the left crank goes "over the top" when pedaling hard.

This is a surprisingly common, and frequently missed, casue of unwanted noises. Generally you should check the items above first, because they're easier to deal with. You can't reliably check the tightness of the bottom bracket mounting without removing the cranks, but sometimes you can diagnose it this way:
Turn the cranks so that the left crank is alongside the seat tube, wrap both hands around the crank and seat tube ans squeeze the crank hard toward the seat tube.

Then turn the cranks so that the right crank is alongside the seat tube and repeat this. Listen for a creak/click.

It's a sealed cartridge, square taper BB (with max 5k miles on it) in a Revoution Courier, if that's relevant. Does Sheldon's diagnosis apply to such BB? If so, is there any scope to adjust it, or its installation, to get rid of the creak?

There's no play in the BB, or none that I can feel. The creak is more pronounced with extra pressure on the pedals (obviously) and more so with extra pressure on the right pedal in particular. Would that mean I should focus on the right hand side of the BB if I do attempt an adjustment?

Or do I bite the bullet and replace?

Thanks in advance for any hints
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Posts

  • thistle_thistle_ Posts: 5,597
    Often a mysterious creak from the bottom bracket can be fixed by taking the cranks off, taking out the bottom bracket, cleaning it a bit and reinstalling.

    My work bike had a very loud creaking under load and the above fixed it last night. The crank retention bolts seemed a bit loose, just tightening them up might have solved it.
  • bucklbbucklb Posts: 296
    Thanks for the response.

    I pulled the BB out, cleaned & reassembled & it seems have done the trick. But that said, last weekend when I stripped & regreased the pedals the problem disappeared for a day or two. We'll see.

    The existing BB is a Chin Haur, ch52-68, 116en, bc1.37x24t. Looks like the best bet for a replacement, when the time comes, is likely to be a Shimano un55, but they come in 115 or 118 (and not 116). Anyone have a suggestion which would be the better bet, please?
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  • NaugasNaugas Posts: 10
    I'd go for the 115.

    As for creaking noisec, they can come from the strangest of places and are very hard to localize. The saddle or saddle post creaking can be perceived coming from the BB area. Chainring bolts that needs to be tightened are another thing easily missed.
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