What do you think about degreasing the interface between a threadless stem and a steel steerer prior to installation? Thomson says I should, so I will do it their way and install it dry for the time being.

Though I usually like greasing that spot to stave off rust from water pooling in the stem cavity and rusting the steerer. I have also found that it makes disassembly go smoother later on.

I clean, then grease.

GREASE before assembly to avoid a stuck stem later.

Ditto for a seatpost.

Cheers

Are you talking about a threaded QUILL stem that slides into the steerer? If so, then yes, clean then grease. You don't want a stuck stem. If you are talking about a modern, threadless stem, like Thomson, then, no grease per their instructions.

@Velocivixen: Sorry, I should have made clear that I was indeed talking about a threadless stem. I'll edit the OP. But, anyway... Seriously, no grease? sounds like a recipe for rapid corrosion. On the other hand, I should probably defer to Thomson's instructions... Color me torn.

Thomson like to use wimpy 3mm bolts for the steerer and bar clamps on their stems, at least on the Elite X2... that might have something to do with it.

If you're concerned about doing it dry, just use carbon paste. It's grease, but provides more grip for a given amount of clamping force rather than less.

It's probably a good idea to disassemble it every year or two, to make sure you can.