I had a RH cup loosen on a Gitane, so it can happen if it is not extremely extremely tightly screwed in.
I have also noted on a few circa 1950 Italian bikes that the edge of the bottom bracket shell has been given a hefty centre punching after assembly so as to deform the material into a C-spanner notch on the cup - obvioously only works with a cup designed to be wrenched with a C-spanner. This makes the cup hard to unscrew and is clearly intended to prevent loosening during use, so it was obviously perceived to be a problem. I concur that a securely fitted cup is hard to remove after it has been in a few years.
Hugh Thornton
Cheshire, England
From: dtshifter@aol.com <dtshifter@aol.com> Subject: [CR] RH (clockwise) BB Cups.....was Legnano BB Wuestion To: johnb@oxford.net, classicrendezvous@bikelist.org Date: Wednesday, 9 February, 2011, 18:05
In ~40 years of riding and working on bicycles, I cannot remember either an Italian or French bottom bracket fixed cup (RH) which had loosened!! In fact, as many of you can attest, many French threaded fixed cups seem to be somewhat "immune" to the removal process!!
Is this actually a problem??
Chuck Brooks
Malta, NY NEUSA