Mavic bb?
 

I just acquired a bike frame that has a bevel worked into the edge of the bottom bracket shell on both sides. Is this the infamous adaptation for the Mavic bottom bracket setup? BSC cups still screw into the shell, albeit with a little difficulty. Can I still use a conventional bottom bracket, or should I seek out the Mavic unit?

You can still use a regular bottom bracket -- the chamfer only affects the first couple of threads. Might need to get the threads chased, as the transfer from the bevel to the start of the threads can be a little rough.

All true, but I wonder whether the BB shell/threading was damaged, as that was why a lot of the Mavic BBs were fitted back in the day: to salvage a frame with screwed-up threads. Or the OP just wanted a sealed BB...I'd consider that the BSC fixed cup won't have a strong "shoulder" on the face of that BB shell to bear against, so rather than machine-down the face (and reduce the width of the shell) I'd just do a light facing to insure that it's square and apply Locktite Blue to that side.

Have you seen this?

http://tinyurl.com/dzbyc

yeah. I just bought one yesterday. I still haven't made up my mind what BB to use, though. I'll try the mavic when I get it - it looks to have the same taper as a Campy, but might be longer than I'd like. This one had very weird-sounding measurements...was a 631 (starfish) crank still in use in 1998?

I had the same problem. I tried a shimano UN73 BB with a plastic cup on the LHS and it keeps on slipping. I used an old shimano metal cup, found on with a longer sleeve and this seems to hold. The mavic BB tends to loosen the BB shell.

Isn't stronglight selling an unit similar to the mavic one?
http://www.zefal.com/stronglight/pag...keyProd=jp1000


Herve