Author Topic: Bent BB shell  (Read 200 times)


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Bent BB shell
« on: June 15, 2020, 05:23:40 PM »
My wife's steel bike fell over whilst on a roof carrier (my fault, I'd clamped it in). It fell down onto it's drive side, and appeared to have bent chainrings. I replaced the chainset... And the front mech just to be sure... I thought I'd sorted it, but my wife said the chain rubs. I've yet to establish if it's througout the pedal stroke or only part.

I decided to replace the BB as its14 years old (and I was unsure whether it was bent). When trying to install, both halves thread in fine individually, but once the drive side is in, the non drive side just won't go in. It seems to rub against the rest of the bb. I'm presuming the drive side end of the BB shell was dented and has left the two faces out of true. Is that possible? Could it be fixed? Anything else to consider. Thanks.


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Re: Bent BB shell
« Reply #1 on: July 03, 2020, 11:29:24 PM »
I'm no expert but I would have thought it unlikely that the BB shell has been deformed to the extent that it will not accept a BB.
1 Does the old BB go back in OK?
2 Can you measure the inside of the shell with anything accurate like a vernier gauge?
3 if you can't use a vernier gauge then maybe cut something stiff to fit inside the BB and then rotate it to check if it binds? No exact but it might show a deformation.
4 can you maybe the drive side only half way and put the non drive side in and then do half a turn each side till it's fully in? I'd lube the inside the NDS cup.

Sorry not sure what else to add but I think it's unlikely to be bent shell.

good luck.