My sigma documentation calls my 26x2.0 apples a 2114 perimeter. Says 700x28=2149, 26x1.5=2026. The 30+mm discrepancy between cateye and sigma (and 2.35 vs 2.0 at that) is greater than the difference between 26x2.0 and 700x28 on the sigma doc, and if my sigma doc went out to 26x2.35, the real discrepancy would probably put the 700x28 and 26x1.5 pretty close together too.

Actually the sigma doc has 26x2.0=700x20, so there are some equivalencies that the algebra-minded could use to extrapolate the discrepancy among the documentations...