Originally Posted by
dedhed
Rather than remove the whole fork, really all they need to do is remove the top nut and stem to expose enough steerer tube to measure as the top nut is threaded on the steerer tube.
once the top nut is removed the OP will need to preserve or readjust the bearings while reinstalling it.
You're right. I was being a little anal to suggest the measurement be made on the unthreaded portion.