Help please!!
Alloy seatpost is jammed in kids aluminium frame – I think it is jammed at the bottom – he had the seat right down, and lots of jumping.
Lots of WD40, and it was possible to turn it with a pipe wrench, but not get it out. The top is now mangled, with basically nothing to get hold of. Is there any way of rescuing this bad situation? I was wondering about an engineers and a reamer??

Clamp the post in a vice and turn/pull the frame.

Freeze kit from plumbcenter round the seat-tube might help too, but that’s a long shot.

take the wheels off the bike, clamp the top of thpost in a vice and twist the frame. Should give you enough leverage.

It’s too late for that – the small bit of the post that was protruding is now cracked – so it will have to be some way of either cutting it out, or gripping it from the inside – screw in threaded bar etc…….

cut down the clamping slot.
find an appropriate shim
& use the next seatpost size down?

if theres enough showing, drill holes through it and use the holes to fix something a bit more securely to it?

or heat the seat tube all the way down with a blow torch, and dump a load of plumbers freeze stuff down the inside of the seatpost at the same down

tis a tricky one!

Turn the bike upside down an soak it in wd40 – by soak i mean keep going back every few hours and ading more oil – marinate like this over a period of 2 days and you should be ok to remove using the vice method OR you can cut it with a hacksaw

ok just re-read your post ignore last comment

If it was turning before it broke off I reckon the large threaded bar is your best shot without doing too much damage. You could then use it as a slide hammer.

Happened to me once with son Jamie’s bike. You need to get a brand new hacksaw blade, and cut the seatpost along its length inside the seattube very delicately for as far down as you can reach, until you have split it. Obviously, try not to saw through the frame. Then you can tease out the post with screwdrivers and long-nose pliers. Sounds difficult and hit-and-miss, but it worked for me. And the frame was aluminium too. Should only take about 3 hours.

If you don’t feel that you can cut out the post your self then an engineering company will be able to do it easily.
If you want to do it your self then go with the soaking for a few days in wd40 type fluid and then using a threaded bar down the inside.
If the top is still on but cracked then just twist it till it then snaps off.

Thanks guys – off to see my mate at the engineering works – probably should have gone there before I messed it up myself!!.