the bikes I have are 1980 and 1981 they measured 34. But hell it was dark... and my caliper is a Chinese cheapo digital... lol. Certainly close enough. The question really boils down to... will the 38mm gaiter snug down to a 33 or 34 mm fork tube? I think I will buy three pairs and if I have to I will slit the 38mm section and allow it to snug down to 34... Same for the 55mm end if needed.