[CR]Bicycle Threads

(Example: Framebuilders:Rene Herse)

From: <Hughethornton@aol.com>
Date: Thu, 30 Jun 2005 17:22:33 EDT
To: classicrendezvous@bikelist.org
Subject: [CR]Bicycle Threads

English bottom bracket and freewheel/fixed cog threads go back at least 100 years - my old BSA has these same threads except that the bottom bracket cups are both right hand threads and locked by cotters. Was the right cup changed to a left thread when cotters were dispensed with? Or was it later when it was realized that a right-threaded cup would tend to unscrew.

It was logical that ISO would, in effect, adopt the English threaded bottom bracket because of the left threaded right cup. The other common standards, French and Italian, both had the disadvantage of a right threaded right cup which had to be done up really tight or Loctited to stay put.

Hugh Thornton
Cheshire, England