Originally Posted by
FBinNY
It's a fairly straightforward job for a skilled mechanic, and poses no safety issues of any type if you have a 1" steel steerer with a 7/8" ID. The ID is critical for two reasons. First it confirms that the steerer is of the same type as used on threaded forks and has enough wall thickness. Second you'll need the 7/8" ID to fit the stem.
Interesting thought. I was under the impression that threadlsss steel steerers had thinner walls then threaded ones since they didn't have to allow for thread depth. However, I just measured a steel steerer cut-off from a Kestrel EMS Pro threadless fork and the ID is indeed 0.875" (22.2 mm) so the wall thickness is the same as a threaded one. I wonder if this is typical.
I agree that it is a job for a
skilled mechanic using good sharp threading dies. Extending existing threads on a threaded sterer is relatively straightforward but starting from scratch is a lot more difficult to do right.