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Bottom Bracket Shell Issue

dee4life2005dee4life2005 Posts: 773
edited September 2016 in Workshop
Looking for some advice.

Had a creaking/knocking noise coming from my bike recently and after all the usual culprits were checked it was still there. I'd stripped, cleaned and greased the crankset and BB threads (hollowtech2) but that didn't cure it so I took them off again for a closer look. I then discovered a hairline crack around the circumference of the aluminium bottom bracket shell on both sides ... it's a carbon frame. On re-assembly and close examination of this area I can clearly see the shell moving up to 1mm when under load (weird though, it does it less with less load, so a TT effort produces little noise, as does a hard hill effort).

I can't feel the play when the noise occurs, but it doesn't change the fact that the shell is definitely moving slightly. It's not affecting riding or gear changing, yet.

I can't find much info online, and was wondering if the two sides of the shell are somehow linked together and therefore the worst I'm going to get is some dodgy shifting and a bit of a rocking feel ... i.e. it's not like whole shell is going to slide side to side in a catastrophic way.

I'm assuming it's not something that can be easily fixed, and unfortunately the bike only has a 2yr frame warranty and it's 4yrs old (Beone Diablo - it has done 32,000 miles though).


  • Also, this is maybe a long shot. But, if I was able to somehow remove the shell, could I clean up that area and install a press-bit BB instead ... or is that just wishful thinking. I'd be a shame to write it off.
  • keezxkeezx Posts: 1,316
    You might be able to install an adapter with BSA thread , that's what I would think of, if the original part is not available.
  • Try contacting BeOne. Even though it's out of warranty they may be willing to help, you've got nothing to lose by asking. CF repair shops often can install new inserts. You could also try removing it yourself, measuring the OD and checking with some frame building suppliers for a match and epoxying in place.
  • In some carbon frames the BB shell is a metal shell bonded into the carbon. I've seen a few Boardmans where the whole shell has come loose when trying to release the BB bearings.

    If it's properly loose you might be able to punch it out with a drift and rebond it with the right adhesive. After all, that's what was done in the first place.
  • Thats certainly my hope, although I've got a new bike on order ... it's a good excuse to N+1 afterall :lol:

    It does appear that the non-driveside at least is properly loose as the shell seems to rotate with the BB cup ... might make it difficult to remove the cup, but that's a different issue. Once the new bike arrives I'll give it a proper examination but if I can punch it out (carefully) then I'll definitely give a few things a try to fix it - nothing to lose after all. Would just need to find the right adhesive / epoxy to rebond it with.
  • If you are Midlands based, Carbon Bike Technics at Moira near Burton regularly re-bond bracket inserts
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