Dear Pat,
This inch thing is to be replaced by an ISO
standard (formerly ETRTO metric standard) for tire- and rim sizes.
I have found some URLs about bike tire
sizes.
On this site I found another folly of this stupid
inch standard:
"Does "Point Seven Five" Equal "Three
Quarters?"
Note that the inch-based designations sometimes express the width in a decimal (26 x 1.75) and sometimes as a common fraction (26 x 1 3/4). This is the most common cause of mismatches. Although these size designations are mathematically equal, they refer to different size tires, which are NOT interchangeable. It is dangerous to generalize when talking about tire sizing, but I would confidently state the following:
Brown's Law Of Tire Sizing:
Note that even some tire manufacturers get confused about this. In particular, some Continental models are mis-marked, using a fractional designation where they should be using a decimal.If two tires are marked with sizes that are mathematically equal,
but one is expressed as a decimal and the other as a fraction,
these two tires will not be interchangeable.
Two more sites:
THe ETRTO European
Tyre and Rim Technical Organization standard:
Han
----- Original Message -----
From: "Pat Naughtin" <[EMAIL PROTECTED]>
To: "Han Maenen" <[EMAIL PROTECTED]>; "U.S.
Metric Association" <[EMAIL PROTECTED]>
Sent: Tuesday, 2004-12-07 10:14
Subject: Re: [USMA:31591] Imperial and Dutch
schools!
Could you give us some more information about this paragraph, please?
> These inch sizes for bicycle tires are condemned for the future. An
> international metric standard is slowly replacing them. This inch standard is
> really stupid: a 27� wheel has a larger diameter than a 28� wheel!!!
Cheers,
Pat Naughtin
Geelong, Australia
61 3 5241 2008
[EMAIL PROTECTED]
http://www.metricationmatters.com
