Re: [CR]Why 70mm for Italian BB?


Example: Framebuilders:Richard Moon
From: <Philcycles@aol.com>
Date: Mon, 4 Feb 2002 12:28:50 EST
Subject: Re: [CR]Why 70mm for Italian BB?
Cc: classicrendezvous@bikelist.org


In a message dated 2/4/02 9:10:36 AM, tom_s_dalton@yahoo.com writes:

<< What IS whacky is the mixing of, metric and "English" units on Italian thread specs. BBs are 36 millimeters at 24 threads per inch???? (Campy axles and hanger bolts are similarly confused). I think this is because many machine tools can cut an infinite range of diameters, but threading options are restricted by the lead screw pitch. >>

I believe at least some of this can be explained thusly: after WW2 American machine tools were sent to Europe to help rebuild their industry. This may explain the prevlance of non metric thread pitches. Phil Brown