Removing stuck or seized seatpost?

it seems like my aluminium seatpost has become one with my steel frame :(
so any kind of bashing and twisting isnt helping.
need to get my hands on some ammonia shit, or caustic soda.
don't quite understand the hacksaw trick tbh.

at least it stops your seatpost from getting nicked!

Ok - i have the same problem, but it is easily solved - however it will fuck the paint job

Basically you take it to Mend a Bike in Fulham, and the dude there heats up the seat tube with a torch. Now initially the aluminum expands faster than the steel around it, however as it cools the aluminum shrinks faster, at which point he whips out the seat post, et voila - only problem is that the process strips the paint - he has done a couple for me, and it works a treat.

I might have got the exact metalurgy process wrong, but it does the job

http://www.mend-a-bike.co.uk/

Put the seatpost in some jaws (bike upside-down) and use the bike as leverage

does caustic soda ruin paint?

This could be useful http://www.sheldonbrown.com/stuck-seatposts.html

I've been looking into this for a seized stem and it was suggested that Rostoff Ice, a product made by Wurth and available from car parts shops may well do the job.

I'm going to try it because I don't want to start mucking around with caustic soda if I can possibly help it.

I'll post results.

Semicolons

That's the bit just before your ass-hole.

I also have the problem. Hoping Evans cycles can clamp it in and twist the fuck out of the post. If not, thief proof seat pin.

HEAT!
As someone mentioned... the Aluminium (Post) has fused with the steel alloy (Frame) and they are like chemically getting it on! The Caustic soda does work. Not tried Diesel... But Heat also works. I got a steel fabricator to put their torch to the seat tube. Heat it up til it loosens! You do loose paint from the frame! I didn't care coz I was re-spraying.

But the perils of not getting it out!!!!!???? I was riding through rush hour traffic with a heavy bag on the same frame with a seized post (the first time it happened)...... It snapped at the seat collar! I fell off backwards (It was an old Kona so I was a little more rearward in my seating than your average LFGSS member!)! Basically the same chemical reaction that is causing the seizing...will eventually cause enough corrosion to snap it. BE WARNED!

I've got the same problem with a post, I'm not worried about the paint but will heating it with a torch affect the integrity of the tubing/frame? I'm gonna pop next door to the mechanics 2mrw and get them to blast it with a torch, just wondering how hot to get it? I don't want to end up with a molten mess.
cheers

will heating it with a torch affect the integrity of the tubing/frame?

not to my knowledge

So this evening I went to the local car spares place and they had some freezing agent in a can like this stuff by Wurth. I started to explain that I needed to get an ali stem out of a steel tube and they said talk to this guy, pointing to a chap talking on the phone. He turned out to be a rep from Wurth and gave me a free can of Rost Off Ice.

He told me how to use it - spray all over the ali for about 10 seconds, then wait another 20 - 30 seconds and it will come away, no problem. He told me I may need to repeat the process 2 or three times.

I got the stuff home, did exactly as he suggested, and then after the can was empty I sawed the stem just above the tube so I could release it from the rest of the frame.

Next attempt is going to be to using heat.

just blow torched my seat tube black and the paints flaking off but theres no movement from the post hot or when cooling off. I fear cutting out is looming ever closer unless anyone has any more ideas?

Interested to hear how this works out, as my steel post is now stuck tight in my steel stem. Meaning that the QR on the clamp is now a bit null and void.

My try hammer technique this weekend and progress from there.

tried everything, heat didnt work, cold didnt work,coke+malt vinegar,didnt work ,many chemicals didnt work,....padsaw £8.98 from b+q worked, if your prepared to lose the seatpost its the easiest way, lots of work but you will get it out

I found this interesting: Old (New to me) 531 Paconi - Stuck Stem - Bike Forums

the person used lye to dissolve the aluminum stem but preserve the steel frame.

The classic method framebulders use to get truly stuck aluminium seatposts out is to melt them out - the aluminium melts before the braze or tubing gets affected as long as you watch what you are doing with the oxy-acetylene flame. A few weeks ago I had a seatpost stuck in an MTB frame that had over 10in stuck inside the seat tube - there is then no alternative to melting it. Of course the paint does get destroyed.

With micro-adjust seatpins most will eventually come out using a vice to hold the pin and levering the frame around - there are various freeing agents avaiable from car accessory shops that definitely help the process.

Jah for sure! When I said heat, I meant HEAT! I think there may be quite a difference between an industrial torch and a domestic style can of butane with a nozzle!

I got a metal fabricator to torch the frame. Yes you loose paint, but as hilarystone says, the aluminium always melts before the steel.

Ok - i have the same problem, but it is easily solved - however it will fuck the paint job

Basically you take it to Mend a Bike in Fulham, and the dude there heats up the seat tube with a torch. Now initially the aluminum expands faster than the steel around it, however as it cools the aluminum shrinks faster, at which point he whips out the seat post, et voila - only problem is that the process strips the paint - he has done a couple for me, and it works a treat.

I might have got the exact metalurgy process wrong, but it does the job

http://www.mend-a-bike.co.uk/

called them up and said it would cost me 25 quid per part stuck. i have 3 parts in my frame!!!

shit

Has anyone actually tried household ammonia?

i dont think it works as well as caustic soda tho. and you need the strong stuff. household is diluted too much i tried it, and no it didnt work for me. havent tried caustic. dont really want to get all these scary chemicals. lol

^ Ta much.

caustic soda aint scary.. honestly its quite tame.

My post is well and truly seized. I managed to break the weld at the top of the post where it attaches to the clamp through leverage and heating with boiling water, and I tried two weeks of spraying oil at it. Are there any bike shops or workshops that you could recommend who will pull it out for me? It's getting too uncomfortable to ride any serious distance on.

Cheers!