>Steve Leitgen wrote:
> A local shop guy has a Mondia and I have a Raleigh with french BBs.
>Finding parts can be a problem. (I'm missing the adjustable cup) An
>English cup seem so fit but.... Do I trust it?
English cups are a wee bit smaller than
French/Swiss, (34.8 vs 35 mm) but have a slightly
coarser thread (24 tpi vs 25.4 tpi0
>So, is it possible to tap the BB out to Italian thread? Will it weaken
>(or crack) the BB shell? French is 35X1 and Italian 36X1.
Actually, Italian is 36 x 24 tpi. (1 mm thread is 25.4 tpi.)
>Will that 1mm. be a problem?
Depends on the shell thickness. If you do it, I would highly advise using a cartridge type bottom bracket, not a cup and cone unit. Actually, I'd advise that anyway...
Jerry Moos a écrit:
>It is possible to tap out a French BB to
>Italian, but this is done mostly when the BB
>thread is badly damaged. I'd never tap a Mondia
>to Italian. And if it is Swiss instead of
>French, Italian won't work anyway.
Actually, it will.
>I think a better option is to install a Phil
>Wood BB. Phil still makes French, and Swiss,
>mounting rings. What really puzzles me is a
>French-threaded Raleigh. Never heard of such a
>thing. Raleigh did have their own thread on
>some models, which was different from English,
>but it shouldn't match French. In fact,
>according to Sheldon's site, the old Raleigh
>thread had a left-hand fixed cup, like English,
>so it cannot be tapped to Italian, which has a
>right-hand fixed cup. (Unless you can
>completely gind [ream] off the old thread, then
>cut Italian).
That's what you have to do with _any_ of these threadings, because Italian is a whole millimeter larger, 36 mm as opposed to 35 mm for French/Swiss, and 34.8 for English/ISO/Raleigh.
Whether this is doable depends not so much on the original threading, but on the thickness of the BB shell...some of them are not all that thick, and you can run short of material when you ream it out to Italian size.
Sheldon "http://sheldonbrown.com/cribsheet-bottombrackets.html" Brown
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