Bicycle Mechanics - Stuck stem. Super-stuck stem.

I picked up a vintage Motobecane Super Mirage for $25 yesterday. That's the good news. The bad news is the stem is stuck in the fork and when I say stuck I mean imagine something stuck and then imagine that it's stuck the same way two tubes welded together are stuck, times that by 10, and then you're on the road to understanding how stuck it is.

It's an aluminum stem and I figured some sort of steel/aluminum corrosion bond was sticking it inside the fork, and if I broke that bond it would come out. I tried hitting it with a mallet in various ways and nothing happened (the wedge is completely dislodged, btw). I sandwiched the forks between two 2x4's, bolted the 2x4's to a gate, and then put a long straight bar through the stem and started pulling. The idea was to twist the stem and break that bond. What happened is so much force was applied I bent the handlebar clamp part of the stem. That was a lot of force, the clamp is (was) very sturdy and the stem didn't move a millimeter in the fork tube. There was so much force, even though I had the forks clamped over a 3 1/2 inch area, right beneath the crown, I think they may have bent just slightly.

What can I do? I've sprayed wd-40 in there but I doubt it will do anything. My next idea was to #1- widen the bolt hole through the stem if I have a big enough drill bit to try to weaken the metal and then, #2- secure the frame, top-tube down, onto a workbench, with the large cup of the headset on the edge, and then place a piece of wood in the neck of the stem and start wailing on it, trying to force it out.

See drawing:
http://img154.imageshack.us/img154/6348/plan0yo.th.gif (http://img154.imageshack.us/my.php?image=plan0yo.gif)

Any other ideas?

plug the bolt hole in the top of the stem,turn the bike upside down, and pour in ammonia through the fork crown. That is the release agent for al/steel bonding. Do this outside or in well ventilated area.

Oooooo. I'll try that. Thanks.

I recently ran across a Peugeot frame that had a stuck stem. Under closer inspection I noticed that the bike had a front end collision at some point and that the head tube was bent slightly. I think the fork tube also got tweaked which made the stem one piece with the fork. Just a thought before you bust out the chemicals.

if the stem is not original it may be a standard stem jammed into the french fork. In which case you may need to get extreme

2 days of soaking in ammonia did nothing. I've found other tips- like cooling the aluminum down so it shrinks a little, but that did nothing too.

In the vintage thread a guy had the same problem and he's having to cut the stem and hack it out from the inside with a hack saw. My question is, has anyone ever had a shop do this for them,if so, what did they do to get it out?

Well, sounds like you've already bent the stem clamp and possibly the fork as well. Maybe the easiest solution now is to just cut the stem so that you can remove the fork from the bike. Pick up an inexpensive replacement fork and stem and be done with it.

Hi, i had the exact same problem. Get the hacksaw out. Be patient and careful and dissolve the aluminium.....

The quickest way to uses this method would be to cut away as much aluminium as possilbe - and uses a very strong sloutiuon.

http://www.bikeforums.net/showthread.php?t=199130
Old (New to me) 531 Paconi - Stuck Stem - Bike Forums

Interested to know. Have you got anywhere with your problem ?

2 days of soaking in ammonia did nothing. I've found other tips- like cooling the aluminum down so it shrinks a little, but that did nothing too.

In the vintage thread a guy had the same problem and he's having to cut the stem and hack it out from the inside with a hack saw. My question is, has anyone ever had a shop do this for them,if so, what did they do to get it out?

I had this problem and I just cut clean through the stem with a hacksaw. Once the bolt was cut, everything came loose. I grabbed what was left of the bolt with pliers and pulled it out easily.