Most threaded headsets have a keyed washer (one with a tab) in between the adjustable top race and the locknot. I'm NOT having problems with those types.

The ones that ARE giving me trouble are the rarer threaded headset types that don't have a keyed washer, but rather use one which is threaded on the inside. (Maybe it's not technically a washer - perhaps "spacer" would be the correct terminology?) It's a donut-shaped part with notches on the outside for turning.

Where I get into trouble is, when trying to tighten the locknut, the threaded washer often wants to turn along with it. And with the threaded washer turning, the adjustable race turns too. So what happens is that when I begin to tighten the locknut even a modest amount - say a half-turn - the adjustable race has also turned 180 degrees, and of course the adjustment ends up wayyy too tight.

I noticed that sometimes when I tighten the locknut, the threaded washer stays put, the way a keyed washer would. This is what I wanted, but it seemed to be "random" whether the threaded washer was going to turn or stay put. So is there any way to ensure that the threaded washer (and by extension, the adjustable race) stay put when cranking down on the locknut?

Put a wrench on it and hold your preload in place while you snug down the lock nut.

There are two ways to handle this. The right way is engage the notches on the side threaded of the washer with a spanner wrench. While a common bike spanner wrench is to big to hold the washer in place, there are other options that were discussed in a previous (which I couldn't find right away)post (pin and hammer, pliers); I use an AR-15 spanner wrench. https://www.amazon.com/BARSKA-AR-15-S...tool+or+wrench



The other way is to insert a thin keyed washer between the locknut and threaded washer.

The round threaded piece is a locknut, just without flats. To adjust properly you need to use that as the locknut. It's ugly but you can just grab it with large pliers to do so if you don't have the right tool. But there should be a keyed washer between the round locknut and the upper race in most cases. Another option is to eliminate the round locknut entirely and replace with spacers. If you do enough work to come across them often then buy a tool for the lockring.

It's a lockring. Like on a BB, only a bit smaller.

Usually a PITA; [MENTION=103762]onespeedbiker[/MENTION] has the gospel here.

Or you could just bugger it off in favour of a spacer or trim the steerer a tad.

Oh, it's a lockring. That makes sense.

Thanks for the tips. After realizing my BB hook wrench didn't fit, I was trying to hold the damn thing in place with a screwdriver on one of the notches, but I was just too clumsy.