Headset Spacer Question
 

I've been playing around with headset spacers trying to get my stem down a little.

Is it OK, to remove the last spacer and put the stem on top of the top cap, or do I have to keep one spacer in there? If it matters, it's an FSA Z-series w/ a carbon top cap.

And yes, I'll cut the steerer as soon as I find a position I'm comfortable with. :)

The answer depends on the headset/top cap and stem designs. The issue is that something has to bear on the centering cone and press it without touching what surrounds it. So if the cone is under the top cap, then yes, or if the bottom of the stem is square and won't touch the top cap in lieu of a cone above, then yes again.

But some stems and touch the part below and not sit squarely on a centering cone, and that would interfere with function. This is a rare problem, but you need to check for it. If in doubt, you can always use a 1/16" spacer under the stem.

Thanks for the info. How would I know if there was a problem, just an inability to tighten it all down without binding?

If it's a carbon steerer tube you should check the manufacturers instructions. Some say you always need a spacer below the stem. Some say you always need a spacer above the stem.

That's one clue, the other if the cone fits into the top of the top cap, is to look for a small gap under a spacer or the stem proving that it's bearing on the cone without bottoming. (on designs where the trim cover is basically a fancy spacer, and the cntering cone hidden underneath, the correct fit is engineered in and you needn't worry.