The eighties something Steve Bauer frame set pictured, hung in The Old Shed, for a couple of years, simply because the steering stem was held fast, in the fork stem.  Several attempts to forcibly remove the stem proved to be futile and I did not want to use excessive force.  Doing so, on one occasion resulted in a broken front wheel axle, coupled with a twisted out of true fork set.  Not the best way to work on a vintage road bicycle!

Before getting into removal of a stuck steering stem, let's consider how to prevent the darn thing from getting stuck in the first place.  The easiest way to ensure that a steering stem or seat post, be they alloy or steel, from seizing into place is to install the component with grease.  Smear a thin coat of grease onto the surface of the post/stem before inserting it into the seat tube or fork steering tube.  It is also a good idea to ensure that tube into which the component will be installed is clean and also coated with a light layer of grease.

To remove a stuck steering stem, or seat post for that matter, it is easiest to work with just the frame set, as opposed to a complete bicycle.  That said, this procedure will work just fine with an assembled bicycle.  However, if you attempt to remove a stuck seat post from an assembled bicycle, you will absolutely have to remove the bottom bracket to ensure that it did not become contaminated with metal filing created when the offending post was cut out.

One way or another, the bicycle or frame set should be held in place.  This will make it much easier to operate a hand saw and allow for greater access and precision during the operation.  A Work Mate or clamping table of some kind serves this purpose well.  But ensure that you are not over clamping the frame or fork set.  In this example, the whole frame set is held in place by the steering stem which will be destroyed anyway.  Clamp it as tight as need be for step one.

Step one is simple.  Begin by removing the long bolt that runs through the center of the steering stem.  Clamp the stem itself into the holding device.  Using a hack saw, or even just the blade, cut the top of the stem off about 3/4" above the head set nut.  This cut does not have to be perfectly square but try to get it close.  And ensure that you leave enough sticking out of the fork stem to grab onto when it is time to remove the remainder of the stem.

With the top of the stuck stem removed, it is possible to now remove the front forks and set the frame set aside.  Clamp the forks into the work stand, once again being careful to not clamp onto fragile tubing or fork blades.  The fork crown is a good place to secure the forks and an additional clamp can be used elsewhere to impart just a bit more stability.  Keeping the whole assembly stable will help greatly when attempting to slot the remaining portion of the stem.

And slot the stem is exactly what will be done next.  With the fork set clamped in the Work Mate, insert a hack saw blade into the opening of the stem.  It might be necessary to first file the hole a bit bigger to allow the hack saw blade to fit.  With the hack saw fitted into the stem, slowly and carefully make a single lengthwise cut all the way through the stem.  Achieve this task safely but making a few strokes and then looking at the results of the effort.  Take your time and get a feel for what you are doing.

Listen to the sound the hack saw blade makes when cutting alloy.  Now, tip the blade a bit so that the end furthest into the stem hits the steel of the fork steering tube.  There is a distinct difference in both sound and cutting feel.  Careful attention paid to this difference in feel will help ensure that you do not actually damage the fork steering tube.

Be extra careful at the open end of the steering tube.  At this point, it is easy to cut into the steel without feeling the difference in metals being cut.  And there is a little trick to help with control of this task.  The hack saw blade can be turned around so that the teeth face backwards.  Doing this will make it a bit easier to deepen the part of the cut that is furthest from the opening.  Again, go slow and get a feel for the results of each effort.

With the first slot cut all the way through the alloy of the steering stem, make a second parallel cut about 1/4" from the first.  Again, exercise caution, go slowly and watch for results.  The results will more than likely prove quite satisfactory.

With both cuts complete, attempt to tap the the center slug out.  Tap gently!  You do not want to drive the remainder of the stem into the steering tube of the fork set.  It is also a good idea to grab the protruding piece of the slug with a pair of needle nose pliers.  Rock or wiggle the slug back and forth in an effort to dislodge the slug.

It might be necessary to attack one or both cuts with the hack saw blade again.  If you are anything like me, you will have failed to cut all the way through the first time.  Once again, just be careful and work slowly, listening to and feel for what is happening.  After making a few more passes at cutting the slots, try wiggling the slug again.  Sooner or later, it will come free and slide out of the opening.

With the slug removed, use a pair of water pump pliers or something like it to slightly collapse the remaining piece of the steering stem.  Now, pull the piece out.  It might still seem snug but once it starts to move it will come out easily.

Good luck.