Originally Posted by moxfyre
Most low-end Japanese bikes use the JIS headset size
Hiya moxfyre,
JIS, Japanese Industrial Standard, was just that: a standard. Low-end, mid-level, and top-end frames were fitted with forks with a JIS crown that measured 27.0mm. I have a top o' the line Maruishi Pro w/ Tange Prestige frame and fork, an '85 Club Fuji(mid-level) and an '81 Panasonic Sport(low-end) that all use JIS headsets. Needless to say I have backup headsets for all my rides.
Originally Posted by rat_factory
JIS steertubes are still 25.4 OD, but the races have a different ID?
Threaded steertubes measure 1 inch in diameter. It's the crown on the fork that is either JIS(27.0mm) or ISO(26.4mm). It may not sound like much of a difference, but it is. I once made the mistake of trying to put a 26.4 Dura Ace aluminum crown race onto a 27.0 crown and ended up splitting the crown race
Here ya go miamijim: