I have an On One Inbred SS Reynolds tubed mtb that has a Thomson seat post stuck in it. My LBS have tried to pull it out without any success and in fact it so tight ,last week they managed to snap the seat post trying to prise it out. They have cut the remaining seat post down so it is flush with the frame but told me there was nothing more they could do as none of their power tools fit inside the seat post as it has an oval profile inside. Anyone have any cunning ideas what I can try next?

Couldn’t you get a Dremel with a round ended cutting burr on it and (gently) cut grooves into the metal until you can turn it into two halves?

Yep it’s all in the bible:

http://sheldonbrown.com/stuck-seatposts.html

How much is left in the frame?

I removed about 5in of alloy post from a steel frame at the end of lady year with caustic soda.

£2.50 from Boots. Couple of hours and all was good.

Thanks for the tips. I think I might give the caustic soda tip a go and see what happens.

Coke, or caustic soda + lots of time.

This will eat the rust / crap away over time. Time as in a week, not a few inpatient hours.

“They have cut the remaining seat post down so it is flush with the frame but told me there was nothing more they could do”

that was pretty unhelpful.

all of the top tips caustic soda, neat alloy wheel cleaner, heat etc
will work.

Place i took mine to did exactly the same – cut it down so there was nothing to grab on to.
Caustic soda worked over a few days…but for gods sake don’t do it in the house, don’t breath it in and definitely wear gloves.
My bottom bracket was sealed so it was easy to fill up the seat tube from the top, if I’d been a little more careful and not rushed as much I’d have got away without needing a re-spray, but it tended to fizz and froth out of the seat tube and over the sides.

Grease the outside of the post before you ad the soda, will offer some protection

Was in this situation last year. 2 weeks before I had to get my seatpost out to get my bike in a box to fly.

In order of things I tried (following Sheldon’s recommendations):

1) Coke / Ammonia etc
2) Riding bike all week with seatclamp undone
3) Gentle twist in a vice

Then things got destructive:

4) Steelsons crushed the tube
5) Tried the longways hack saw but it just wasn’t working – bits still welded in.
6) Resorted to Caustic Soda method…

This work but my recommendations are:

Strip the frame completely. Use blu tac and plastic bags to bung up the holes. What I did was put the frame upside down, bung up the (now flush) seat tube / post and inject the caustic soda using a plastic syringe into the bottle bosses before taping up. It will fizz and go and you may end up with a Mt Vesuvius coming out of the BB shell. If it gets too hot rinse the outside of the frame tubes. Once it stops fizzing empty, rinse and repeat. I got my seatpost out in 12 hours with a final overnight soak.

DON’T get the stuff on your paint – rinse off immediately if you do. It’s paint stripper.
DO NOT get the solution in your eyes. It WILL blind you. Wear goggles.
Wear PVC gloves.

If your hands / skin feel soapy you’ve got stuff on your skin. Rinse immediately with vinegar / lemon juice other weak acid.

BE CAREFUL. Have FUN!

I had the same happen on my old p7. Seatpost got stuck, took it to Cyclesurgery in Manchester who, after snapping the post flush with the top of the seat tube, helpfully told me that I needed a new bike (all with a totally straight face too).

I then took it to Ken Fosters in Chorlton and the mechanic set about it with a blow torch. 10 minutes later the post was out. There is some bubbling of the paint, and it needed some percussive maintenance (by way of a nice big hammer) to get it back in shape, but it’s totally fine now.

Could you get a star fangled nut inside the remainder of the post? You could use a bolt + big washer to get the remainder out perhaps, or at least get it moving. With care of course!