Originally Posted by
Amt0571
If the steerer is carbon you have to put a spacer on top and the steerer should be cut slightly above the stem.
If the steerer is metal, you don't need a spacer on top.
With CF steerers, it depends. For instance, Cervelo explicitly states not to put any spacers above the stem, and that the top of the steerer should in fact be 3mm below the top of the stem.