Bicycle Mechanics - bottom bracket threading questions???

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jtricer1973
11-06-08, 02:24 AM
Ok, I have some questions regarding BB threading. I know that in the old days there were several different threads used bike bike makers. English, Swiss, French, etc. Is there a standard thread that is now used by most, if not all manufacturers? Can threading be changed and if so how? Also, as far as threading goes, I assume we are talking about the threads that the cups screw into. Is this correct?

Reason why I ask is that I have an old Peugeot that I am building up. I want to replace the old cottered crank with an alloy unit. Seems like it shouldn't be that hard, but then you get into all the threading issues. This bike is an 81 model, so I think it has Swiss threading. I will confirm this if I ever manage to get the old cotters out. LOL! If it is Swiss threading (or french) it seems like I am severely limited as to what cranks and bottom brackets I have available to use.

Hope some of this makes sense to everyone. I have just never messed with replacing cranks and/or BB before, so I am kind of confused.

Unapomer
11-06-08, 03:05 AM
Messing with the old Peugeots are a real headache because of the French threads, if you want to upgrade the bottom bracket or headset especially. The bottom bracket thread is 35mm x p1. Info is available on Sheldon Brown website. When I upgraded my UO-8, I was able to get a Sugino 35 x P1 bottom bracket, I think Tange used to make them also, but good luck finding one. The stem size was also odd, 22mm, just a little smaller than the standard 22.2mm. If you google "Sugino 35 x P1 bottom bracket" you'll get some hits for people building fixies out of old Peugeots and the headaches they encountered. Good Luck !!
HillRider
11-06-08, 08:47 AM
These days English is by far the most common threading with Italian still around but increasingly rare. French and Swiss threading have disappeared from new bikes.

One possibility, if your frame is threaded French or Swiss (35 mm), is to have it reamed and retapped to Italian (36 mm). This is sometimes done to salvage ruined English bottom bracket threads too.