Actual Rim Size 700c vs. 27" Tubular vs. Clincher

Retro Bob wrote:
On Mon, 27 Sep 2004 01:31:12 GMT, Mark Janeba wrote:
I think the 622 (and 27"=630 IIRC) is the "bead seat diameter." That
is, the diameter of the tire bead and not the outer diameter of the rim
(which would be larger).

Yeah, I can see that. It would match my tubular measurements exactly
then. What's the "bead seat" on a clincher - the level the rim tape
sits at ?

Nearly. Mostly. The "bead" in a clincher is the sometimes-wire
sometimes-kevlar-cord hoop that circles the tire along the bottom of the
sidewall and is "hooked" by a similar bulge inside the rim side to hold
the tire on.

In a properly seated tire, the bead is *pretty* close to the rim tape,
but it varies with different rims (some have a deeper "spoke bed" than
others).

The "bead seat diameter" is just the diameter of the wire-or-kevlar
hoop, as I understand it.

Mark Janeba