Hi All

It seems the aluminium seat post in my carbon framed road bike – will not budge ….

any ideas to get this out without damaging the frame would be great

thanks

K

Soak it in Plusgas, or if you don’t have that some gt85 might do the trick, then put the seatpost in a vice and twist the frame, gets loads more leverage. As a last resort you could try cutting the seatpost close to the frame then cut through it from the inside towards the frame, then you might be able to get it out.

Not sure I would use plusgas on a carbon frame – not checked out the solvent in it and compatibility with epoxy resin.

You could maybe try some vinegar if there is a hole up from the BB shell to the seat tube – bit early for me to remember if that effects aluminium oxide though.

Sheldon says caustic soda should work: http://www.sheldonbrown.com/stuck-seatposts.html

You could also try coca cola if that fails household ammonia wired for me when I had a seat post stuck in my Klein.

Good point andyl, hadn’t thought of that.

I’d rather use Plusgas than caustic soda!

Can you apply gentle heat i.e. hair dryer to the seattube and then try twisting the seatpost out?

Or wrap a bag of ice around the seatpost to cool it down and shrink it slightly. CF has a very low rate of thermal expansion so heating the seat tube won’t do a lot (unless it frees up some kind of chemical bonding that has occurred.

Could you get a mate to hold the seat while you twist the frame to get some leverage on it (just be careful with bending the rear end of the bike).

Did you use that carbon assembly paste when putting it together?

Thanks all – I will try again when I get home..

I am scared of damaged the frame though….

I will let you know

My cousin had this problem a few weeks back with his scott genius and for some reason i said id have a go at getting it out. I did as sambob said and cut the seatpost an inch above the seat tube then with a hacksaw blade carefully put two cuts down the post to make a chanel then crushed it with mole grips and pulled it out. It was a proper ball ache and i was constantly aware i could trash his frame if i cut into it. Luckily its fine

It’ll be well bonded together by crusty white deposits, which will prevent any of the usual suspect fluids from freeing it.

I found the only way was to cut it out;

It took 8 hours, 5 blades and a lot of cramping fingers. If you look at how far the tube was in, I had to make 4 seperate cuts to free up the sections of post.

Bit scary when it’s a carbon frame; you can tell you’ve cut through the post by the noise the blade makes, so do it carefully and don’t chop your frame. This was in 2006, the frame is still in service.

Look on the web for ‘hacksaw blade holder’, and buy the longest hacksaw blades you can.

You can also wrap the top of the blade in insulation tape to form a handle. if you measure how far in the post is then place a piece of tape at the same depth on the blade so you dont cut past it into the frame. Oh and a torch helps

Aren’t the “crusty white deposits” aluminium oxide, capable of being dissolved by acid?

…and when it’s done, take the BB out, buy 3 big bottles of the cheapest fizzy water and dump them down the seat tube to flush all the swarf out. This is best done outside…

Aren’t the “crusty white deposits” aluminium oxide, capable of being dissolved by acid?

I don’t know the science bit, but yes, probably. The problem is that the gap between the frame and the seat post, especially in well made carbon frames, is very small so the dissolving fluid can’t get to the stuff to dissolve it.

I talked to TREK USA about mine because I was convinced I’d wrecked the frame and the guy there suggested that it was a problem that took a few years to develop and one which led to them putting drain holes in all their subsequent frames.

He also suggested the use of Hylomar non-setting gasket compound as a way to keep seatposts from sticking.

Take it to a machine shop. They’ll cut the post then ream it until the remains of the seatpost collapse and just pull out. No damage to the frame.

I’ve used caustic soda on a steel frame/alu post, worked a treat after everything else had failed.

Rinsed the frame well as soon as the post was done and all was (and still is) good, not sure I’d try it on a carbon frame though!

There’s a product made by an Italian company which is called Carbomove (or similar) which I bought a couple of years ago to try and free a stuck Campag carbon seatpost out of my 6/4 road frame but haven’t got around to yet.
You should see what ti/Ali/carbon electrolitic corrosion looks like (it pretty much destroyed a carbon Record square taper bottom bracket…)

Take it to a bike shop. They’ll have plenty of prior experience of this if they are any good plus if they kill the frame it is their fault.

Aren’t the “crusty white deposits” aluminium oxide, capable of being dissolved by acid?

Yes, think so – I got a jammed Al post out of a steel frame by using some caustic soda, think it’s a base rather than acid but anyway, it doesn’t affect steel (or carbon, I think, but check with a spare spacer) but does eat away at alu oxide fast. Drain crystals added to hot water (not other way round!) worked to weaken the bond, then twisting in a vice freed it.
You may be able to pour some in from the bottle bosses or BB to free the other end.
Edit to add, I say ‘think ‘ a lot here as I’m not a chemist and don’t wreck a frame on my advise! Just used caustic soda / sodium hydroxide to strip anodised parts a few times, and this seatpost un-jam.

Before i got my cousins post out he took it to two decent bike shops in the lakes 1 tried (not sure how) and failed and the other would not touch it incase they trashed the frame dont blame them either

For stuck post in an aluminium frame we tapped a thread on the inside of the post, screwed in a bolt welded onto the end of a slide hammer, couple of knock on the hammer & it was out.

On something delicate like alu in alu or alu in carbon, I do it with expanding reamers.

@crikey I had to do the same with the same post in a 2009 frame I got 2nd hand! The remains were bonded into the seat tub, messy!

Take the wheels off, stand the BB on a wooden block with a rag over, remove the seat and give the top of the seatpin a good tap with a mallet.

Might be just enough to break the seal and get things moving.