Removing stuck or seized seatpost?

Tried to put in pic, but it didn't work? hmmmmmm.

If there is any post still sticking out try and get some looong pipe grips on it. Also try some of the more chemical atacks like caustic soda (avlible from boot brewing section).

Ok, think i'll have a few nights trying the chemical attacks - the post is about 3-4mm thick, not like my MTB one? Anyone know wo sells plus gas in Central London, Covent Garden area?

A while back I got some from the hardware store thats towards the Regent Street end of Brewer Street on the north side of the road, sorry for the slightly obscure street directions but I can't remember/never knew the name of the shop. I know someone said they thought the coca cola trick worked on the same principle as caustic soda as they're both base solutions but I'm pretty sure that coca cola is mega acidic, not basic and the chemistry of the caustic soda idea sounded more plausible. I personally would still go with the plusgas, but I wouldn't give up on the caustic soda just because coca cola didn't work.

A few listed here.

http://maps.google.co.uk/maps?f=l&view=text&hl=en&q=hardwear+store&near=London&btnG=Search+Businesses

Tried a few places at lunch... nowt! There is a Halfords if I take a detour going home, maybe they stock it? And a car supplies place further up in Mile End, but might be closed by then? Will then try the caustic Soda if that don't work... Grrrr.

i tried loads a places for plusgas when my post got stuck, no joy anywhere in london, you can get it from amazon or random places online, but shipping is steep, probably due to the chemical nature of it. Eventually got my dad to post a small bottle down from the shire. was worth it though, run it down from the top and in through the bottle cage holes, left upside down over night, came out with a statisfying pop the next day :)

The Shire.... Where abouts? Will have a hunt tonight and see what I find?! Otherwise, it's online I go!

tomiskinky The Shire.... Where abouts? Will have a hunt tonight and see what I find?! Otherwise, it's online I go!

Worcesterhire, the only true Shire

Hmmmmm, I think you'll find the real shire, is York Shire! Ha ha ha.

polybikeuser A while back I got some from the hardware store thats towards the Regent Street end of Brewer Street on the north side of the road, sorry for the slightly obscure street directions but I can't remember/never knew the name of the shop. I know someone said they thought the coca cola trick worked on the same principle as caustic soda as they're both base solutions but I'm pretty sure that coca cola is mega acidic, not basic and the chemistry of the caustic soda idea sounded more plausible. I personally would still go with the plusgas, but I wouldn't give up on the caustic soda just because coca cola didn't work.

Yeah, Coca Cola is acidic.

I would suggest concentration hydrochloric acid, that'll literally dissolve the seat post. But it'd probably mess your frame up a little bit.

What would stop it from dissolving the seat tube? :)

Well the hydrochloric acid would react with the aluminium in the alloy considerably more violently than the steel frame. If you did it pretty quickly then rinse the frame with lots of water after removing the post, it might work :P Although then you'll have the problem of rust, so you'd need to dry out the frame with some kind of drying agent.

You'd have to be pretty desperate to try any of that!

in spain they sell agua fuerte in bottles a concentrated sulphuric acid
it's like that stuff that drips from the alien in the film of same name
don't spill it and don't use it to unstick your seatpost

The really concentrated acids/bases are horrible. I remember I was using some conc. hydrochloric acid in college, and added it far too quickly (this a couple of drops, literally, from a pipette) to another mixture and it evaporated, leaving me to breathe in hydrochloric acid gas. Not nice, at all!

If you're seriously contemplating using concentrated acids or bases can't you instead just keep it simple and go straight in with a shaped plastic explosive. Slightly trickier and maybe just a tad bit more dangerous but oh so less smelly. Seriously though I was wondering about the wisdom of using caustic soda but I'd definitely think twice before mucking around with conc sulphuric or hydrochloric acid.

i personlly would try the saw method, just slowly cut the inside of the seatpost. chemicals canny be good for the steel.....

Yeah, probably the best idea :) You'll end up loosing half the skin on your hands with all these nasties.

It's a really think post... will get pics up to show when I get a minute.

My problem was an aluminium post in an aluminium frame. Having read all suggestions above I came up with a variant of the hairdryer. First I wrapped the frame in strips of old rag as tight as I could. Then I poured on a kettle of near boiling water, and out came the post. Worth a try to save a trip to the chemical factory.

You could always start off using some vinegar. If you need it stronger you could boil the vinegar for a little while to concentrate it. I doubt it'll work but it's an idea.

Still stuck! Gone through 4 saw blades so far! Tried Caustic soda which dissolved part of the post, so gonna try that again to dissolve it a bit more!
It would appear that a good length of post is seized in there, and cannot get the blades to cut into the post beyond 3" down!!!
Not happy, wanted to take it to get painted today...

If you heat the caustic soda up it'll increase the rate of the reaction hence making it dissolve the post quicker.

Try tying a massive rag around the seat tube, pouring boiling water over it and then pouring in warm (not boiling!!!) caustic soda.

Should speed it up big time.

Can you twist the post yet?

Nope, it aint budging at all, got some big grips on it, but nothing! Gotta try get a good seal as I tried it last night and it leaked out!!!

This sounds like some job. do you know anyone called Arthur who could just pull it straight out. It's worth a try as nothing else seems to have worked.