Seized seat post

[WKB]

Any advice for removing a badly seized seat post please? It is Al alloy in a steel downtube.

[jb]

Hi
If your not bothered about the seat post, first try soaking it with wd40 type stuff then heat up the steel tube with a paint stripper hot air gun (but not enough to strip the paint, obviously), then twist the post using some stillsons whilst holding the frame down firmly.
Otherwise try cutting off the bit of seat post you can see about 5mm above the steel tube, then slit the remaining bit left in the tube with a hacksaw blade in a padsaw, a laborious task but you get there in the end. Two slits opposite may be needed. If you leave 5 mm sticking out the top you can pull on this with some pliers or whatever. If its a mountain bike post with lots left in the tube you may not be able to do this though.
Another method is to attach a slide hammer to it but it depends on what tools youve got available.

[PW]

Ammonia poured down the seat tube from the bottom bracket, with the frame upside down. Main problem these days seems to be finding a source for the ammonia. (Do this OUTSIDE!)

[Steve]

This takes a while, but:

Method one - worked for me.

Soak it with penetrating oil regularly for a week

Then get a BIG adjustable spanner and put it around the clamp part of the post.
Or a big pair of self-gripping 'stilsons' on the tube part

Put a long piece of pipe over the spanner and turn it.

You may need three people to hold the bike down.

Method two - works for someone else.

Saw the seatpost off just leaving a bit to get hold of.

Stick a hacksaw down the resulting hole and laboriously saw a slot through one side of the seat tube from the inside out.
You can feel when it gets through the aluminium to the steel.

Saw slowly as you - obviously - don't want to saw through the frame. A few scratches won't hurt much.

This has been done - with more care and patience than a saint normally has - inside a carbon fibre frame with success

Once you are through, It is likely that you will be able to twist the stem out.


Steve

[Steve]

And another thing.

To minimise damage...

Once the stuck tube starts to move, apply more oil and work the stem back and forth to get the oil in the gap before you try to get it all the way out.

[CJ]

And when you put the new one in: use proper anti-sieze compound (preferably Alumslip on alloy parts) and NOT grease.

Grease is made from oil and soap. Squeeze it hard and the oil may depart from the soap, which then reacts with rust and aluminium to form a kind of cement!

[WKB]

Enormous thanks for these very practical suggestions. The job proceeds.

WKB