Joseph B. Reid wrote on 2002-07-12 00:19 UTC:
> The British bicycle industry has from its beginning been totally non-metric.
> The usual tire diameter was 28" or 26" with a 1-3/8" cross section. I believe
> European manufacturers have copied some of the imperial dimensions, such as
> chain link length.
The components used by the British bicycle industry are defined in BS
6102 "Cycles". The tyre and rim parts of that standard are identical to
ISO 5772 "Bicycle tyres and rims". I have copies of these standards, in
case anyone is interested in details. British Standards are commonly
available in many city council public libraries in the UK (you have to
ask the librarian usually).
ISO 5775 tyre specifications list the width and diameter in millimeters.
An example for a "wire edge" tyre from the standard:
A tyre having nominal section width 32 mm, nominal rim diameter 597 mm
and recommended inflation pressure of 400 kPa shall be marked as
follows:
+---------------------------+
| 32-597 inflate to 400 kPa |
+---------------------------+
The BS 6102-5 / ISO 5772-1 standard is around a dozen pages long and
contains a detailed specification of how to measure the section width
and rim diameter, as well as conversion tables to older tyre designation
schemes, including inch-based ones.
Markus
--
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org, WWW: <http://www.cl.cam.ac.uk/~mgk25/>
