Bicycle Tutor

On the road bike I am trying to fix, I ran into another problem. The seat post is stuck inside the tube and I have tried lubing and it and letting it set, taken pliers to it, even lightly tapped the seat post with a hammer to see if I could jar it loose. It was in a shed for several winters (in the rainy NW) and it probably has some rust in it, but it will simply not budge. Any thoughts of how to get it out? It is an old steel post and I can easily find a used alloy one at the shops here so there is no need to keep it in good working order. Thanks.

In some cases they can get so bad that there's nothing you can do. That said there is a similar discussion started here, and bike forums has some more ideas here.

Depending on the severity of the corroded and chemically welded parts there is one "trick of the trade" fitters would use to free heavily corroded bolts. Heat. If you have access to a soldering torch, not electric but flame, you cold heat the seat tube whilst applying a twisting pressure too the seat post. If this doesn't work then the corrosion may be so bad that too much of the metals have corroded and a new seat post will be too sloppy anyway.
Worth a try.
If that doesn't work, cut the seat post about an inch above the seat tube and try a hacksaw blade cutting the inside of the seat post. Cut as deep as you can along the length inside and then grip with large multi grips and try and twist it free.
Regards,
Rick.

Just like to share my story here:

I have a 30 year old bike and the alloy seat post has probably been sitting in the seat tube for the last 30 years. It seems the bike has been stored indoors throughout its life so the situation shouldn't be that bad, but I just couldn't move it! Sprayed WD40 from the top and tried to twist and pull it with the saddle and no luck. Sheldon Brown's site suggests soaking it with ammonia, but it requires taking out the BB and administering harmful chemicals into the frame, which I am really reluctant to do unless I have no choice.

I paid a visit to the LBSs. The first one, without even trying, said they have to charge $100 minimum. Obviously they didn't even want to take the job. The second one got it out for me in 10 minutes, for free!

The LBS owner first tried twisting with the saddle; then tried twisting with a vice grip; neither worked. He then sprayed some degreaser on the top, add a few drops of wet lube, and started hammering down on the seatpost. This seemed to be the magical move that "broke the seal" as the seatpost did get hammered down the tube after a few blows. As soon as it moved, it was easily twisted and pulled out with the vice grip. Frame saved, seatpost saved, saddle saved, BB untouched, no chemical down the frame. Didn't see much aluminum oxide on the seatpost. It was mostly rust from the steel frame.

So hammering down on the seat post is an effective way to break the seal, provided your seat post has a solid capped end (mine does) for the hammering to take place without harm.

As an aside, the LBS owner said he's never seen a seat post like mine: a solid top and such short length.