DIMcyclist

My apologies, but the tagline should read, "Have any of you ever TRIED this?" (I caught that a minute too late, and of course- it can't be changed: it's set there permanently in digital concrete.)

Hi Everyone,

I have a question for you regarding older 21.1 headsets...

Would it be possible to modify a 22.2 headset into a 21.1 by simply swapping out the lock nut?

As by way of background, I'm refurbishing an early '80s Univega Rover (pretty cool old frame, I have to say); it's fully equipped with a 21.1 fork, stem, and headset (a Tange or Tioga MX 2 by the look of it; and it's apparently JIS/ 27.0). Unfortunately the HS seems to be wearing out. It still works; more or less... but it doesn't properly seal; the crown race is pitted & corroded (def. needs to be replaced), and the cups are showing very (very) early traces of brinelling.

Now... while I'm aware that there are still some NOS 21.1 BMX headsets cheaply available, I've also noticed that there are much much better JIS headsets available in 22.2. So, as a test towards this modification, I took the 21.1 lock nut from the Univega's HS and tried it on a fork that I know is JIS standard, with a 22.2 stem diameter, and it fit just fine: threaded right on; no trouble at all.

So: if the outside steerer diameter & thread pitch match up, would there be any real drawbacks to making such a modification?