What does the "C" mean in tire sizes?
 

I am looking to get some new tires for my bike. My current tires are bontrager race lite 700x23c, on Bontrager Race rims. when I look at tires at some online shops I see 700cx23 or 700x23, but I have not seen 700x23c.

Could someone explain what the "c" means?

I don't want to get a tire that will either not fit or change the riding characteristics from being a different dimension. I understand that each tire has itsown characteristics but I want that to be the only change. :thumb:

Here's what I found in the Wikipedia article on bicycle wheel http://en.wikipedia.org/wiki/700c#70...eels.2FISO_622

• For rims the ISO designation lists the rim diameter (where the tire sits) and the rim's inner width, both in millimeters and separated by a cross, along with a letter code for the rim type (e.g., "C" = Crochet-type): 622x19C

I have no idea what "Crochet type" means, however. Perhaps someone else knows.

I found an explanation on another forum that suggests there used to be A, B & C width rims and the industry finally settled on the C size as the standard.

"C" is the letter after "B". Modern road bike tires are mostly 700C
http://sheldonbrown.com/tire-sizing.html

C just used to mean a certain tire/rim combo that are supposed to be 700mm in diameter, 622 rim + the rest tire. All the other letters are pretty much not used any more in 700 series wheels.

These days a letter is still a concern only for 650 series wheels. B and C are still around in that realm.

thanks guys. So essentially I don't need to worry about the C, so a 700x23, 700cx23 or 700x23c will all fit the same.

yeah.
just don't try it with 27"
but oddly enough, the germans use 28" instead of 700c

Italians have also been known to use 28", on tubulars.

23 is reserved for mm? It doesn't look like it wants that c.

23 is mm.

I need to go to Wiki. This is incorrect. ISO is meaningless. That is an ETRTO designation.

Crochet type means clincher rim. I just posted the ETRTO drawing for this in another thread (funny).

The explanation you found is correct. The 'c' designation is archaic and even '700' is a nominal size that has no meaning. The '23' designation does mean casing width but I've seen plenty of derivation there from brand to brand.

I think crochet, if found on some French rim marketing materials, might even specifically mean hook bead rims, since crochet hooks have, well, "hooks". But yeah, wiki's wrong about what C means.

I figured it was French but that makes sense as in crocheted sweater.

The 700c comes from the French sizing convention where there were four 700 designations that ranged from A to D (narrow to wide) and although each rim was of a different size, the effective diameter of the tyre was 700mm at the outside. The 700 A, B, and D designations are now obsolete although the 650A, 650B, and 650C sizing convention is still in use.

700c is now used for any rim that is 622mm at the bead seat or any tyre that fits this rim size and the secondary number denotes casing width in mm.

I thought it went fat to skinny, A-D. Least that's the way it seems with 650 B,C.

Tyre sizing is one of those things that could make one's head explode...

650A is the French equivalent to the 26 by 1 3/8 wheel / tyre used on most British 3 speeds but was also used for a narrower high performance wheel / tyre, 650B is a little smaller rim wise (584mm) but fatter tyre wise, and then you get 650c which is a designation for a smaller high performance wheel / tyre with a 571mm rim

650A is still used as a naming convention as it separates the 590mm / 26 by 1 3/8 from the modern 26 inch MTB wheel which is 559mm rim