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I have a steel hardtail with an ovalised bb92 shell, it seems, from new.
I spotted it after the original stiff turning shimano BB failed in 5 months.
I've successfully installed a metal cupped BB which seems to have forced the shell round, but I'm clearly limited in BB choice.
The manufacturer has said it happens from the welding heat from the stays and seat tube, and have offered to ream the BB shell, but I'm unsure. Surely reaming an oval hole leaves two sides the right size, and two sides too large? Is this actually a problem in a BB? I would have thought it would be - do I run the risk of it being too loose after its been reamed?
No one?
manufacturing defect.
Return it under warranty and get a new one.
The effect of the welding is BS.
I wouldn't be impressed with that - but I think press-fit BBs are a silly idea anyhow.
Yes, reaming it round will mean that it's not a brilliant fit - and on something that's meant to be a press fit, making the hole bigger isn't a great idea. If they know that it distorts on welding, then the sensible thing to do would be to make it undersized and ream it to size after welding.
Yup, warranty.
Hmm. Thanks Ben. Confirmed my view on things.
Disappointing. I would much rather have a standard BSA BB, but that isn't an option with this particular frame.
Can't you get an adapter pressed in so you could use a standard BB?
I don't think there are adapters for PF92 - it's too wide.
The effect of the welding is BS.
Yes, as a framebuilder that kind of thing is my problem, not yours.
Could you not build the bottom bracket up with weld or brass, and then ream it out, meaning it ends up the right size?
My whole position on this has been that I was sent a frame that has been inadequately finished/missing quality checks, but they assure me that reaming the BB shell will be the end of the problem.
I've been asking for a new frame, a point that they've been either studiously ignoring, or assuring me is not that much of a problem to warrant a new frame.
If they dont offer a new frame then get your money back.
no messing about its a clear cut manufacturing defect.
Is this a frame that's actually made in the UK? If not, then I'd wonder about their ability to do reaming like that properly anyway - importers aren't manufacturers.
This is direct with the small manufacturer in Germany.
Anything can be fixed of course, but that's not the point - it should have been built right in the first place. Reaming it is not a proper fix, unless it's undersized.
I'm guessing it's not undersized because I successfully pressed in a replacement BB with alu cups!