wkatastrof

Greetings,

I've had a '76 Schwinn Continental for five years now and it has served me very well. I just recently overhauled the entire thing, but realized that the passenger side of the bottom bracket has widened, that is to say oval-shaped. It is every slight, but now the cup can move up and down in the shell.

Do I just ride it until it breaks?
or
Is there a way to repair this?

A machine shop would need to be involved, I suppose.

I ended up wrapping the cup in teflon tape, two passes. But there is still play and its worse than I thought.

Please share your ideas. I would like to repair this and do not care for those who suggest to get a new bike or a lighter one.


Attached is a poor phone photo of the bike.

Metacortex

I've never heard of this happening just from normal riding, those frames are built like tanks. Did you crash or somehow bash the bottom bracket against a curb? Are you sure the cups are not part of the problem, what happens when you swap them side to side?

If the BB shell has truly ovaled I guess I'd use a vise or set of channel locks (with wood shims for paint protection) to squeeze it back to round. A final option would be to replace the frame (or entire bike). Continental frames can be had for pretty cheap (and entire bikes can be had for not much more). For example here is a 22" Continental frame (same size as yours) that if it sells at all will probably sell for the opening $10 bid: https://www.ebay.com/itm/231041552639

Looks like they raised the opening bid to $40 after I posted this. You can get a whole Continental bike for that plus the shipping (or less)...

zukahn1 

Just a qeustion are you riding it as a normal classic geared bike or FG/SS? If a FG/SS you need to trash this frame and man up and get a better bike.

wkatastrof

No, I have not crashed the bike and there is no damage to the exterior of the bottom bracket shell. The bottom bracket is still the shape it should be. From normal use (thousands of miles)the cup has enlarged the bottom bracket shell ever so slightly (1/64 to 1/32 of an inch) so that the cup now has some play in it and the bb shell is thinner at the 6, 7, and 8 o'clock positions. The more play, the faster the wear.


My guess is that it needs to be filled in with something and re-drilled to 51.3mm.

I'm riding this as a geared bike.

gaucho777 

Did you see the thread I coincidentally started earlier today regarding my own bent BB shell? Some suggestions over there may be applicable in your case, too:
https://www.bikeforums.net/showthread...vice-needed%29

I do find it very odd that your BB became ovalized through normal usage. (In my case, the frame fell onto a cement garage floor.) Could your BB spindle be bent?

wkatastrof

The difference between the problem with my shell is that its too big so the (unthreaded) cup moves around while your threaded cup won't fit in the shell since your shell is bent.

On another note, it would be great if you share your steps for using oxalic acid. My biggest worry would be saftey, spillage, and proper disposal.