Originally Posted by
HillRider
While I've read of several posters who have reported successfully using a tubing cutter on aluminum or Cr-Mo steerers, in general I agree with Burton. A tubing cutter tends to leave a raised ridge on the outside of the cut and a sharp edge inside. If you are willing to file off the burrs, ok, but a fine tooth (32tpi) hacksaw with a cutting guide works much better.
As BCRider recommended a wrap of masking tape can be a suitable guide but I prefer a stainless steel radiator clamp. It provides a well defined and solid edge to guide the cut.
Even with a fine-tooth hacksaw, you're going to have to take a file to the steerer tube anyway.
Finally if you leave the steerer a bit too long and add a thin spacer above the stem, having an absolutely square cut isn't as important since the spacer will provide the needed square edge for the top cap to butt up against.
I didn't think the top cap should be touching the steerer tube - no matter what.