I recently bought a 1″ threaded headset to replace the one on my 1990 Kona Lava Dome which I currently use as a tourer / commuter. I thought the LD had a 1″ headset but the crown race on the one that arrived would not fit the fork. The headset was stamped 26.4 and the figure 27 appeared on the fork. Is this coincidence or slightly different sizing?

Ta.

Looks like you should be able to get the crown race milled to 27mm . . . although the link says A 27mm fork crown race can be milled to 26.4mm, BUT not vice versa. – surely it should be the other way around . . . or have I had too much Guinness? 😕

http://www.sutherlandsbicycle.com/Chapter12.pdf

or have I had too much Guinness

Sounds reet to me. But I’ve been drinking gin so perhaps we’re both wrong?

I’d have thought an off the peg headset would be available rather than having to have one milled out?

http://www.sutherlandsbicycle.com/Chapter12.pdf

From that I need a JIS headset.

Cheers

27 is the japanese industrial standard (JIS).

There is a work around. Take a centre punch and peen the shoulder on the fork where the bottom race sits. Peen it North, South, East & West. That will raise just enough metal for the 26.4 race to sit on tight.

27 is the japanese industrial standard (JIS).

I’d heard of JIS before but didn’t know what it stood for. Cheers.

There is a work around.

Or my old favourite, the knurling tool:

Stein tube knurling tool by Ben Cooper, on Flickr

🙂

http://www.sjscycles.co.uk/mobile/m:part-pro-1-inch-threadless-headset-with-both-264-mm-and-270-mm-crown-races-black-prod17447/

This has both sizes as I just fitted one.

http://www.sjscycles.co.uk/mobile/m:part-pro-1-inch-threadless-headset-with-both-264-mm-and-270-mm-crown-races-black-prod17447/

This has both sizes as I just fitted one.