How do I remove a partially seized carbon seat post

PostieJohn

from a carbon frame.

Over the last few months I've had the headset serviced and BB replaced, yet even though my Bianchi is running so smoothly it's creaking like my knees!

Through this time I've been ignoring the elephant in the room, my seat post.

For a good few years now I've not been able to remove it.
It'll quite happily go up and down to the point of 'my height', but it won't come out completely.
It's as if my seat post is now cone shaped.

Surely this has to be the reason for the noise, even though the creaking is at it's worst when pedaling out of the saddle.

Every time I think 'right this time, you're coming out' I get to the point I'm at now, namely wanting to reach for a hammer!
I know this is bad, so I stop.

Any expert, non hammer related, advise would be greatly appreciated.

sungod

if it'll move, get some lube in there, even water, move it up/down/around, chances are it'll gradually ease

just give it some welly

fwiw when removing the cf post from my frame (stainless steel) for packing in the bike box, i have to straddle the top tube to get weight on there and then use both hands to twist/drag the saddle/post combination out (it has cf assembly paste in there), there's a lot of force involved, yet this is a weight weenie ax lightness post, it survives

PostieJohn

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19729294#p19729294]sungod[/url] wrote:

if it'll move, get some lube in there, even water, move it up/down/around, chances are it'll gradually ease

just give it some welly

fwiw when removing the cf post from my frame (stainless steel) for packing in the bike box, i have to straddle the top tube to get weight on there and then use both hands to twist/drag the saddle/post combination out (it has cf assembly paste in there), there's a lot of force involved, yet this is a weight weenie ax lightness post, it survives

Thanks that's pretty much where I'm at, and always have been.

Liberal grease around the visible section of the post then sliding it and down.
I can even feel the downtube getting hot with the friction.
(sorry there's just no way I can write this without it reading like the porn of my yoof )

Anyway as said I can get it up high enough (I'll stop this soon) but I just can't make the whole thing pop out the end. :roll: I'm embarrassing myself now.

thepainandsuffering

Strip the frame as much as you can, turn upside down and clamp the seat post in a vice*, you can then get much more leverage twisting the frame upwards then you can by using the saddle, keep lubing the post and twisting back and forth. (*this may damage the post).

Failing that as a last resort, twist the post till stuck, get the hacksaw out and cut it off low near the seat collar, then using a hacksaw blade cut slots down the centre of the post that is still wedged in the frame (be very careful not to cut into the frame at the same time). Once you have 4 or 5 cuts right through it will all come out but you'll need a new post.

Monty Dog

Many frames have an aluminium insert inside the seatpost - due to a process of galvanic corrosion, aluminium oxide forms which is hard and abrasive, locking the post in place. Best option is to spray some ACF-50 spray which effectively dissolves the aluminium oxide. You could give it some welly, but there's a risk of breaking the frame - seen it done.

nicklouse

First as the maker about the construction.

If all carbon you don't want to try pulling the parts apart.

Pull the seat post but push the frame. Pulling the frame can make it grip tighter. You need to push from/on the seat collar(clamp).

PostieJohn

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19729364#p19729364]Monty Dog[/url] wrote:

Many frames have an aluminium insert inside the seatpost - due to a process of galvanic corrosion, aluminium oxide forms which is hard and abrasive, locking the post in place. Best option is to spray some ACF-50 spray which effectively dissolves the aluminium oxide. You could give it some welly, but there's a risk of breaking the frame - seen it done.

Thanks I'll give that a try.
As said it's very frustrating as the top 6 inches of the post goes up and down like it was fresh from the factory, then it just 'locks' tight.

I bet after all of this I finally get the post out, clean it up, grease it well, get it good as new, and my bike will still creak like it's held together with sellotape.

Rodrego Hernandez

Turn the bike upside down and pour coke down the seat tube.

Monty Dog

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19729465#p19729465]Rodrego Hernandez[/url] wrote:

Turn the bike upside down and pour coke down the seat tube.

Yeah, cos Cola's gonna work really well when the problem is due to aluminium oxide, I mean they'd never dream of putting Cola in aluminium cans if there was a problem :roll:

On the other hand, a strong alkali like bleach/ caustic soda would also work, but be careful it doesn't corrode the other components...

nicklouse

All the info you you need
http://www.sheldonbrown.com/stuck-seatposts.html
Number 13.

PostieJohn

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19729577#p19729577]nicklouse[/url] wrote:

All the info you you need
http://www.sheldonbrown.com/stuck-seatposts.html
Number 13.

Thanks a lot - the problem is, and it's a new one for me, I understand the theory but can't quite see it in practice. I've spent my life 99 times out of 100 the exact opposite.

The best way to do it is not pulling on the outer tubing, but pushing the big tubing off the small tubing, just pressing on the edge of the outer tube while pulling on the end of the inner tube. Now I knew I would be able to do it. I only needed some way to apply reasonably large force just on the top edge of the seat tube. I took two aluminum plates that just fitted nicely between the seat rail clamp plate and the top of the seat tube (one plate on one side of the seat post and the other on the opposite), with the seat rail clamp screws extended by a few turns. Then I gently turned the rail clamp screws in and the seat post just came out without any struggle I did not apply any more force then, just slight finger pressure on the Allen key while turning the screws. I am sure that a similar method may be used on metal frames and seat posts or any combination of the material. You just need the right length of spacer blocks or some kind of screw attachment to do the pushing off the seat tube from the seat post.

I think I'm being really thick here, sorry.
I can't see how the seat rail clamp screws, which are horizontal, can be used to affect the vertical tube.

Could I put the downtube in a vice between 2 pieces of something sturdy then GENTLY tighten the vice so that the seat post pops out?

sungod

depends on the seat rail clamp construction, mine are vertical (remember he's talking about the clamp screws, not the saddle rails), though even then not all would suit this method

he's using the rail clamp to put the seat post under tension by using the alloy plates as struts between the clamped bar and the top of the seat tube

might not be too good for the edges of the seat tube though, if you want to try it i'd make something to spread the load around the circumference of the tube

downtube in a vice? assume you meant to put seat tube, and no, just no

i'd wondered about an alloy insert, but the fact that you can move the post made it seem less likely - though it raises the possibility that the post is jammed in the insert and the insert is no longer bonded to the seat tube

if you've got a cable detector you should be able to tell if there's metal inside the seat tube

bbrap

If all else fails, pull the post out as far as it will go, cut it off flush with the top of the seat tube, then push the stub right down in the seat tube and leave it there. Then get a new seatpost. Depending on the design of the frame if you take the bottom bracket out you may get the remains out that way.