Originally Posted by
ClydeClydeson
The wiki article is wrong. If C stood for Crochet then what do A, B and D stand for in the same systems? Trick question - they don't stand for anything, but are codes for the different sizes that have the same nominal outside diameter.
If I am wrong, please link to the manufacturer FAQs that support your claim. I looked and could not find such claims except for in the erroneous Wiki article, which does not have a source linked.
Well here you go.....
Continental recommends that you mount bicycle tyres on hook edge type rims only. Hook edge type rims provide a more secure hold, especially with air pressures exceeding 44 PSI (3 bar). These advantages are safety-relevant. From 73 PSI (5 bar) onwards, the hook edge type rims are even stipulated by the ETRTO guideline. This rim type, for example 622 x 13C, is indicated with a rim base diameter in mm (size D), the rim width in mm (size A) and a “C” for crotchet (Illustration 6 ). If the size information on older rims is no longer legible, the rim width can simply be measured by using a calliper from one hook edge to the other. An overview listing the appropriate rim width for every tyre size is also available from ETRTO (also look at the chart 7 ).
https://blobs.continental-tires.com/...otice-data.pdf
To me it makes no sense that the mfr will care to put a C to make some vague reference to an outdated sizing mode. It makes more sense that they would put C after the width to tell you that it is only intended only for a crochet type rim. Some don't care whether you use them on a crochet, hooked bead or smooth rim.
Smooth bead rims have been fairly extinct since the demise of Schwinn and their 27 and 26 inch smooth steel rims. Perhaps since the tubeless crowd is now getting some smooth bead rims we'll see some more on what this truly means.
Maybe they'll clear up the difference between hooked and crochet too. Because while a crochet bead is a type of hooked bead, a hooked bead is not necessarily a crochet bead.