Originally Posted by
eacolin
Hey guys, I'm working on a bike (threaded headset) where I'm swapping out the stem. Yesterday, the stem was loose enough that I could easily rotate it independently of the fork, and remove it with some wiggling. I tightened it, and then today, when I went to loosen it and remove it, the stem is totally, irremovably stuck. If I loosen the stem bolt, it just rises; taps with a mallet don't budge it. If I remove the stem bolt completely, the stem still doesn't budge. How could this possibly happen overnight? I'm up for trying to put oil, ammonia, in it, etc, but it seems like it must be another problem, because it's not like the stem corroded in place overnight. Any ideas? Thanks,
-Colin
Sounds like you have one of those steerer tubes that has a narrower section further down, and now you've gotten the wedge and the stem jammed up against this restriction. Don't know if Sheldon Brown has a patented cure for that on his website or not.
If it was me I'd undo the bolt and then hit the stem from below (use a wooden block in between) to try to dislodge it.