Method below works better on a steel post (on which you can safely crush the end if it is a few inches out of the frame). Soak steel posts with penetrating oil (dribbled in over several days). A sharp rap with a steel hammer may help break the corrosion loose.
According to Sheldon Brown's website the only way to dissolve an aluminum/steel corrosion bond is with ammonia (haven't tried it myself). Tried putting my alloy post in a vice but it was too brittle and just cracked and disintegrated. So I have resorted to cutting it off and attempting to cut a slot with a hack saw blade. Naturally the post is inserted a good 12 inches in to the frame :-( Once the slot is cut I'll try to twist it out or break it up (or at least clear the first 3-4 inches so I can insert another post.
BTW if dealing with an oversize frame/seatpost, I simply cut off the post flush with the frame, cut a short slot in the old post (matching the one in the frame) and then find a smaller post to fit inside the old post.
PPS I'm not the dummy that put an alloy post 12 inches in to a steel frame with no grease. I am however the one that salvaged a sweet Pinnerrello (sp?) from the garbage (complete except for wheels, chain, rear derailleur and a seat).
Chris --- Bob Giordano mist@strans.org wrote:
a vise is good for stuck seat posts. flip over the bike, insert seat post into vise, tighten -but not too much to crush post-, move bike frame back and forth gently and smoothly while pulling up. be very careful to use smooth motions and 2 or 3 people as to not tweak frame.
any other 'stuck seat post' tips?
-Bob Giordano, Free Cycles Missoula
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