Another "stuck seatpost" thread.

[PpPete]

Bought a second hand 531 framed bike off fleabay recently, really nice one for the price. Even the paintwork is good. It came fitted with a gruesome suspension seat post.

I've tried all the usual "extreme unction" methods of getting the thing out, and finally managed to extract all the innards of the suspension system, but I'm left with the outer aluminium shell, of which a good 6" is stuck in the seat tube. This shell has a base (so it's like an elongated cup). There is an inch or so sticking above the seat tube but even belting this with a lump hammer won't shift it.

I'm not going to try heating it...aluminium expands more than steel, and it would ruin the paint work.

If it didn't have the "end" I'd get the hacksaw blade out and saw down the length of it, before trying to fold it up on itself and pulling it out with the mole wrench but I'm worried I wouldn't be able to cut far enough because of the end of the "cup".

I'm sure I recall reading somewhere of a household chemical that would dissolve aluminium but I can't recall what it is.

I've read coca-cola will dissolve aluminium oxide but I don't think it works on aluminium?

Any tips?

 

[MajorMantra]

It's the oxide you want to dissolve because that's what's holding it. Ammonia may work (didn't for me but I didn't leave for long) and caustic soda works as it will eat the oxide, and the aluminium, and potentially you if you aren't careful.

My stuck seatpost was eventually freed with help from the local bike charity. A squirt of GT85, a vise with some pieces of metal with semi-circular cutouts to grip the post and some vigorous twisting did the trick.

Matthew

 

[accountantpete]

Try popping the seat post in a vice and then turning the frame to break the "join".

 

[Joe24]

give it a good wack with a tap-o-meter

 

[Joe24]

I had my seat post stuck in my yellow frame. I had put copper grease on it aswell! Just shows you should take things out and clean them up every so often.
Anyway, i clamped the seat post in my neighbours vice(long seat post) and twisted it.
All i succeeded in was getting the seat post very warm, even with tipping oil down.
So, next thing was to hit the top tube(well my neightbour did) with the seat post clamped. Which bit a dint in my top tube.
So, i decided to sod it, and just wacked the seat post down abit, because the seat post was too high up.
Cutting is another option, dont need to cut it all, just enough to brake the seal so far down, because in theory it should only be the top bit that has bonded?
I did it with a stem, and it was the only thing that did work.

Have fun.
I used my neighbours power hacksaw thing for it. Very fun.

 

[PpPete]

Try popping the seat post in a vice and then turning the frame to break the "join".

There's no "flat" to the seatpost that the vice can grip. All that gubbins went away with the suspension parts.

I've drilled a hole through protruding part, put a big old ChromeVanadium screwdriver through it as a tommy bar (first bar I tried from my workshop just twisted) .

Tried "percussive technology" (a.k.a lump hammer) when it wouldn't turn. Sheared the screwdriver !

Also tried said lump hammer in downward direction to break up join.

No movement at all. Hence question on chemical solutions.

 

[PpPete]

give it a good wack with a tap-o-meter

Is that your biggest hammer?
I've a bigger one than that ! - and I still can't shift the sodding thing.

 

[Joe24]

There's no "flat" to the seatpost that the vice can grip. All that gubbins went away with the suspension parts.

I've drilled a hole through protruding part, put a big old ChromeVanadium screwdriver through it as a tommy bar (first bar I tried from my workshop just twisted) .

Tried "percussive technology" (a.k.a lump hammer) when it wouldn't turn. Sheared the screwdriver !

Also tried said lump hammer in downward direction to break up join.

No movement at all. Hence question on chemical solutions.

Make a flat section, tighten up the vice Thats what i did
you should see the dent in my top tube aswell

 

[PatrickPending]

you'll have tried these

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

years ago my handlebars were stuck - nice people at newcastle university engineering workshop (where I was at the time) popped it in a vice and got it out. Been careful to grease since. Hope you manage to get it out - I guess patience and a vice (with use of chemicals ) are the way to go - see sheldon if you haven't already!

 

[PpPete]

Make a flat section, tighten up the vice Thats what i did
you should see the dent in my top tube aswell

No desire to dent the top tube on this!

But I will be trying to make a flat in the vice tommorrow - if it hasnt all dissolved away from the caustic I just put in it!

 

[Browser]

I was just about to say caustic sod dissolves ali, but you beat me to it! Be careful it don't damage the paint, and be aware that it will give off hydrogen as it decomposes.