Spacers do work on threaded headsets. I installed a new headset on a lovely Vitus 979 frame I got off ebay at Christmas and found that the locknut wasn't able to screw down far enough, so I bought a spacer to fit in the gap. Before the spacer came in the post I was using the crown race from the old headset as a makeshift spacer but it looked absolutely terrible, despite being perfectly functional, so it had to go.
Spacers do work on threaded headsets. I installed a new headset on a lovely Vitus 979 frame I got off ebay at Christmas and found that the locknut wasn't able to screw down far enough, so I bought a spacer to fit in the gap. Before the spacer came in the post I was using the crown race from the old headset as a makeshift spacer but it looked absolutely terrible, despite being perfectly functional, so it had to go.