Originally Posted by
oneclick
Upside down over a plastic bucket,
NaOH solution poured down the inside of the seat-tube - don't make it to strong, wear protective gear - and wait a week (you can take the gear off).
Or make it a bit stronger and be done in a couple of hours.
I used drain cleaner to remove this rather massive bar stem:
Outside, of course. Keep water within reach:
After a few hours:
