Re:
It breaks me bleedin' 'art to see, and even read people recommending the old hacksaw method..corrosive chemicals and even man's red fire...useful sometimes, but, not the right start.
freeze them out! sherlylock and his marin PM offered a good tutorial on the method. I have removed two that way for ringo, no mess or damage to anything else. The post completely re-usable.
If the post is intact, just stuck.....
ebay search crack-it freeze spray for water pipes. £7 or there abouts.
car sponge, tie wraps, carrier bag, vice or some other way of holding the seatpost head.
What i did...
remove BB and/or seat tube bottle cage bolts.
Get seatpost/frame upside down in vice nipped up as tight as you dare.
tear open(like pita bread) the sponge and wrap it round frame local to seatpost insertion, tie wrap in place.
wrap plastic bag around all that. tie wrap or knot in place(helps with splashes and thermal regulation).
If crack-it has no tube, make one(fish tank air line, cable outer) etc.. blast a good 1/3 of tin down into frame via BB or other.
No need to wait..blast rest of tin contents into sponge, impregnating it.
Give it 2-3 mins and use frame as leverage, rock it left and right with increasing pressure(steadily).
If all is well there will be a firm "bang"..it's loose! Now lift as well as rotate.
That should be that. never failed me, providing.....
some dummy hasn't hacked the seatpost head off
!!!!!!
" me mate said i could i could hack-saw it out!" good luck..after 57 blades and bleeding hands. thinner posts maybe but the kalloy alloy...narrrr!
Gloves and eye protection as minimum PPE.