22.2 to 21.1 Headset modifications... Have any of you ever tired this?
 

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?

Are you sure it is a complete 21.2 package and not just a 21.2 stem on a real thick steerer?

I would search for some threads mentioning 21.2 HS and stems.

Might be a trial and error thing.

That will work just fine.

Thanks for the reassurance!

Yup, it is indeed. It's still in the OEM set up for that particular bike, according to the '83 Univega catalog I found online.

I wish I could salvage the original HS, but when I did the math, it would cost the same to replace the whole thing as it would to replace just the worn parts; further, I could get a brand new (and much better designed) Tange/ IRD 22.2 HS for the same price as NOS... which can (apparently) do the job just as well-- IF the lock nuts could be successfully swapped to fit the smaller vintage stem (since it seems the other JIS dimensions are the same for both headsets).

Wish me luck! :thumb:

AOK on using a 22.2mm headset and then substituting your former 21.1mm locknut.

Pay attention to the thread engagement depth into the locknut after the switch though, since you might need to add a washer to allow the old locknut to tighten fully onto the new headset without the steer tube bottoming out inside of the old 21.1 locknut.
I.e., since the new headset might have a slightly shorter stack height, the steer tube may protrude a bit further into the old locknut.