..but how?

Aluminium alloy post stuck in steel frame, no amount of hot/cold, coke, penetrating oil, shouting will get it to move and I need it out asap, so am planning on going for the chop.

Any advice/sympathy/ridicule welcome.

Ammonia .

Will dissolve alu and leave steel in tact.

Failing that i used a fine cut blade on a reciprocating saw to cut a post into 8 – didnt help it was still stick – so much i managed to snap the frame twisting it in the vice was alu post in ultralight alu frame

Snapped frame isn’t an option, can afford a replacement post but not a frame!

I’ve heard about the ammonia trick but am worried about a couple of things:
– ammonia stinks
– it might damage the frame, as it’s a special steel alloy (OX Platinum tubing which has added elements, their names escape me at the moment)
– where do I get it? Rob the Chem dept at school?

Ah, they’re the ones – it’s steel alloyed with Chromium, Molybdenum and Vanadium. How do I work out whether ammonia would damage them, or if the reaction itself could have adverse effects on the frame?

Just worth a try before you cut.Get your frame as hot as you feel safe then squirt (plumbers) freezing spray down inside the alloy seatpost to get the alloy to contract faster than the steel.

Cut the thing out!

Long hacksaw blade, some tape to protect your fingers and get sawing. I did an alu post in a carbon frame, took 8 hours of cutting, but the frame is still in service 6 years on.

What crikey said , the alloy post/shim were stuck in my P7 frame when I got it.Probably took me a bit longer than his 8 hours but I did it over a number of days. You can sometimes roll the partially cut post away from the seatube to get a bit of lubricant down there.