so I've trolled the forums and found no luck so here is my problem..
I have a late 80's Saintropez "La riviera 440" frame, and it has a mystery bottom bracket.
I know that It is not Italian, and no 35 x 1 stamp on the OG cups..so not french, it's pointing towards English threading, but I bought a Shimano UN25 cartridge BB and the removable cup threads perfectly into both sides but the actual cartridge itself wont engage the threads in the least. It also seems to sit funny in the BB shell (the spindle is not centered in the shell on the non drive side)
help please I'm bikeless until I can figure it out
Check and see if its a reverse thread. If the cup threads in on both sides the cartridge should as well. Did you grease it up before you put it in?
If the cup threads in on both sides then it's right hand thread on both sides. French threading is slightly larger than British, it would probably thread in pretty smooth, but I wouldn't want to put any torque on it.
If the threading is the correct direction for a British cup but seems barely the wrong size, it's likely Swiss threaded. But do I read correctly that you're able to thread the same cup into either side? In that case, French sounds likely -- British and Swiss have opposite threadings on the drive vs non-drive sides, so the cup should only thread on one and not the other. French and Italian have the same (right-handed) threading on both sides.