Back again with another query. Got an old Kona that I rescued from the tip in exchange for a fiver many moons ago. The frame was a mess cosmetically so I just wrapped it in electrical tape so it was plain black. Thing is, I like it and want to get on the path to giving it a new lease of life. I know a decent powdercoaters nearby that did my inbred for me so going to go there. The seatpost has been seized in from day one so if possible I'll leave it in for the powdercoating process. Reckon I could get away with it providing it was masked off?
If you’re having it powdercoated anyway why not just blast the hell out of it with a blowtorch - that’ll shift it!
As long as you're not proposing I be the one wielding the blowtorch, I seem to be more half baked than usual these days, it'd be asking for trouble. If I knew a dirt cheap way of getting it pit safely I'd look at it. Had the bike years and goodness knows how long it had been lying around before I picked it up.
If the seat post is aluminium and the frame is steel. Then caustic soda will melt it away easily. Quite impressive when I did it. Just be careful with it.
before you try the nuke it from orbit apporach above! pour boiling water on the seat tube and sparay the seat post with cold spray (for injuries).
If the seat post is aluminium and the frame is steel. Then caustic soda will melt it away easily. Quite impressive when I did it. Just be careful with it.
I did this as a last resort for a stuck dropper. I'd tried all the old wife tails with heat, cold, coke, vinegar, GT85, etc.
When aluminium and steel meet, there's no separating them IMO.
Took two bottles of Soda and a bit of patience but got it out in the end. I'd guess non dropper would be easier to shift.
It'll make a mess of your frame probably but I also powder coated it and it came up like new.
Yeah, I'd get medieval on the post now, it's the best opportunity you'll ever have since it's getting coated anyway.
That said, yes it'll probably be fine just to get it masked off.
I've done the caustic soda technique with success.
It's relatively cheap. You can buy solid caustic soda (sodium hydroxide) from DIY shops. Wear gloves even when handling the powder, keep skin covered and use eye protection. Always wash everything down with lots of water when you are finished.
Add powder to liquid in something that won't melt as it gets hot. From memory I did a 30% weight solution. You cut the seat post about 1 inch above the seat tube. Tape it up so it is water tight. Strip the frame, invert it and pour in the Caustic through the bottom bracket.
Aluminium is much more reactive than iron so it corrodes faster. Again it gets very hot and can boil. Best done outside as it produces hydrogen gas. I had to do this a handful of times over the week. Pull out the remaining seat post with pliers (you are still wearing gloves!). Clean up with a lot of water. I wrapped some fine sandpaper round a pipe to remove the last remnants of corrosion.
It stripped a bit of the paint so I ended up getting the frame powder coated.
Loads of videos on youtube.
Thanks for the replies but I have neither the time nor the inclination to be fannying around with caustic soda, especially as the post is actually seized in a position that fits me quite nicely! If as Northwind says it'll be fine masked then that'll do for me. Gawd knows when I'll actually get round to it, mind....
I bet you'd get it out with a bit of heat and abuse. I can't imagine getting a frame painted with a stuck post! I suppose you could just mask the saddle clamp and get the post painted to match!