The headset on a custom US bike went south. It's a one inch headset with a 26.4 crown race. The pressed races measure out to be 30 mm. I pulled out my trusty Sutherland's and I'm a bit confused. Isn't a 26.4 crown race most commonly found with a 30.2 mm pressed head tube race? I thought JIS was 30 mm head tube race and 27 mm crown race?