1" threded headsets ??

knobby

Retro Guru
Meant to ask about this a while ago when I was putting my Rockhopper together. I was using a Stronglight headset for the build, but when it came to fitting the crown-race I was struggling. Eventually I took it to my LBS who also tried and failed, before discovering that the race ID was 26.4mm, whereas the Specialized fork crown OD was 27mm. So....is there more than one standard 1" headset fitment?
 
Had a similar problem. I bodged by sticking some 1 1/8 spacers on the fork, then putting the race on top loose, hoping it would be held in place by the bearings.
Worked well enough for what I used the bike for, but wouldn't recommend it for any serious downhill stuff.
 
It seems you need a Japanese Industrial Standard (J.I.S.) headset.

I qoute from Sheldon Brown:
"J.I.S. fork crown seats are 27 mm in diameter, instead of 26.4 mm. J.I.S. head tube inside diameter is 30 mm, instead of 30.2mm"

In this table he mentions four different 1" sizes.
 
While he says the
Older or lower-quality bicycles from Asia
top quality headset where still made in that size
JIS (27.0 race) is is the 2nd standard amongst the 4 he mentions.

Shimano's XTR and Suntours XC Pro both came in both ISO and JIS headset formats. (so be carful when you buy 1" btw).
 
Thanks for the info chaps. All a bit too late for me though....I seem to have persuaded a pair of 30.2mm cups into the 30mm headtube of my frame apparently! And in the end I resorted to using crown race from the old headset I was replacing.

JIS items seem to be rather thin on the ground.
 
Damn, this happened to me on my Rockhopper too! Took it to the LBS, he couldn't get it on either. Never did get an explanation though, he simply dug up a crown race that fitted and slapped it on. Good to know.
 
This is unbelievable. I just attempted to fit a 1" threadless headset I got off here a while ago into my Breezer only to find that it seems to be a JIS one (threadless not mentioned in Sheldon Brown link though) so the cups are 0.2mm too small doh (although oddly it came with a spare race which was the smaller correct size!!). The XT threaded one I took out was a ISO one. I had no idea there were different ones! :x :roll:
 
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