Sheldon Brown to the rescue:
Freewheel Threading Type Thread Specification Equivalent I.S.O. 1.375" x 24 tpi 34.92 x 1.048 mm British 1.370" x 24 tpi 34.80 x 1.058 mm French 34.7 x 1 mm 1.366" x 25.4 tpi Italian 35 mm x 24 tpi 1.378" x 1.058 mm Metric BMX 30 mm x 1 mm 1.181" x 25.4 tpi
French and Metric BMX freewheels thread don't work with anything else. ISO, English and Italian are all semi-interchangeable, but it you shouldn't go back and forth between different types of freewheels on the same hub repeatedly.
There are subtle differences between BSA and ISO threads. There is also a difference in the pitch of the threads (one is 60 degrees, the other is 45 degrees? Am I right? Tom? Jamie? Other machinists??)
Sometimes it doesn't matter. There is a little resistance initally if you thread ISO and BSA parts together, but in some applications it is not ideal, specifically fixed gear cogs and lockrings. Aren't you glad there are so many different 'standards' to choose from? Why do they insist on calling it a standard when there are so many to choose from?
Tom Martin Geeking out on threading conventions in Oakland CA
-----Original Message----- From: speedaneze@tesco.net [mailto:speedaneze@tesco.net] Sent: Wednesday, June 29, 2005 5:14 AM To: classicrendezvous@bikelist.org Subject: Re: Re: [CR]What does ISO mean on a Regina Oro freewheel
Afternoon all, Sounds like the USA is ISO 9001 free you are lucky! This is how it all started. Electronics first. International standardization began in the electrotechnical field: the International Electrotechnical Commission (IEC) was established in 1906. Pioneering work in other fields was carried out by the International Federation of the National Standardizing Associations (ISA), which was set up in 1926. The emphasis within ISA was laid heavily on mechanical engineering. ISA's activities came to an end in 1942.
In 1946, delegates from 25 countries met in London and decided to create a new international organization, of which the object would be "to facilitate the international coordination and unification of industrial standards". The new organization, ISO, officially began operations on 23 February 1947. Best wishes Frank Ellingford London UK.
>
> From: "kim klakow" <Akimbo71@gmx.net>
> Date: 2005/06/29 Wed AM 11:58:20 GMT
> To: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
> CC: classicrendezvous@bikelist.org
> Subject: Re: [CR]What does ISO mean on a Regina Oro freewheel
>
> Not to forget that in the 19th and early 20th century all of europe
> measured in inches (or "Zoll").
> As a matter of fact, any faucet, bike part, pipe, you mane it is
> measured in zoll, which coincidentially also means "customs" in
> german. I wonder where the etymology comes in on that one ...
>
> kim
>
> --
> Kim Klakow
>
> Diplom Grafik Designer
> Akimbo71@gmx.net
> +49172-1786481
> Berlin - Germany
>
> 5 GB Mailbox, 50 FreeSMS http://www.gmx.net/
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>
Oil up! Frank Ellingford London UK