the tubulars called 28" now are the rim radius 700c clincher tries to be interchangeable ,
OP, data offered is all kind of nebulous ... get out that metric tape measure..
what is the radius measured from the axle center to the brake post center , brazed on the frame.. ? 285mm on mine.
using the Mafac dimensions for a cantilever caliper [ I measured mine ] .. the frame boss post to the brake shoe post is 25mm ,
combining that should be the bead-seat diameter of the rim, roughly the center of the brake track .. 27"(630) would be 315mm ;
622/2 is 311, the 700c .. my roughly measured 285 + 25 =310mm
Last edited by fietsbob; 05-07-14 at 04:07 PM.