Originally Posted by rpenmanparker

If we are talking about a carbon steerer (I will confine my remarks to that), it is not usually appropriate to cut the steerer tube all the way to 2-3 mm below the stem top however. Many if not most stem and fork makers these days recommend leaving a 5 mm spacer ABOVE the stem. That assures that the stem clamp grips the steerer somewhat below the open top and crushing the steerer is less likely. If things are set up properly, the top of the steerer will be about 2-3 mm above the top of the stem. Then when you put the 5 mm spacer on, the steerer will sit about 3-2 mm below the top of the spacer. As long as the top cap sits fully above the top of the steerer and can pull up on the steerer, all is good. Then I also like the look. Be sure to allow for that when you do decide to cut the steerer. If the expander has a lip that sits on top of the steerer, be sure to allow for its height when figuring everything out.