so you might have seen my other posts regarding this issue. i finally took out the bb in my 50+ year old french frame. very very bizarre. check it out:

inside i found (like i expected) a shimano un-53 english thread bb. the cup was labeled a 73mm but the sticker inside reads 68mm. mislabeled? unless i did it wrong, the bb *does* measure 73mm. oh and the bb shell measures 68mm... can a 73mm bb even fit correctly in a 68mm shell? ok, moving on...

the bb came out just fine, not too easy but not difficult either. looking closely at the threads they seem fine!! after cleaning, i can screw both cups back in easily, no grinding or unusual resistance. once they are threaded in, they sit securely. however -- if only halfway in, there *is* a little play. that seems odd.... but i really dont know as i have never second-guessed a bb before or tried to check the play on it when only half-in the bb shell. is this sort of play normal?

at this point i am tempted to just get another english thread bb, maybe use some locktite when putting it in, and then just forget about it.

but i still dont understand why the threading is this way. could the shell have been replaced? could it have been originally english threaded in the 1940s? could it look as clean as it does if the threading was changed from french to english?

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and another note on bbs related to fixed gear use:

qbp no longer carries any adjustable bbs. this is because, without a fixed cup, they tend to come loose easier. seems like if this is a problem in general it is specifically a fixed gear problem. whats harder on a bb than fixed riding? thats too bad since i was all set on getting an adjustable bb so i could get my chainline perfect. now im not so sure thats a good idea. anyone use this sort of bb without problems? (specifically any of you brakeless riders who tend to be hard on your bike)

If it's of any use, I used a Superbe Pro Track adjustable BB with sealed bearings for a while. Sounds like the bee's knees, right? Nope... while it was indeed nice to have adjustable chainline (and I never had problems with loosening, but I wasn't brakeless then either) the bearings flat-out sucked. I killed one in less than a year. My LBS loaned me another one (they have an amazing collection of stuff) while they looked into replacement bearings, and I froze that one in less than a month. Turns out the bearings are an odd size, and would've been $50/pair to replace. Cheapo Campy bottom bracket works way better now anyway.

Way OT, and I don't have any advice on english threaded BB's. Sorry.