Originally Posted by
noodle soup
This is correct.
Just to make things more complicated, "C" could also be an abbreviation for Celsius.
In fact! But don't.
Those of us in the small wheel world of folding bikes, trikes, recumbents, and minivelos are accustomed to talking in terms of ERTRO designations already, e.g. 406, 451, but wouldn't it be nice if we all dumped the whole 700C/27.5/29er thing and just talked ERTRO? It would make some discussions easier, anyway.