seatpost - seized

021CRETE01

My carbon seatpost is very very tight in my titanium frame.I didn't swing out of it 'yet' as I'm afraid to damage the post. Any suggestions?

Holyboy

Hmm, not sure about ti, I used lemon juice on a seized alloy post in a carbon frame yesterday and got it out, at the very worst you may have to just cut the seat post out, not such a big deal, lucky its not a carbon frame!

021CRETE01

Holyboy wrote: »

Hmm, not sure about ti, I used lemon juice on a seized alloy post in a carbon frame yesterday and got it out, at the very worst you may have to just cut the seat post out, not such a big deal, lucky its not a carbon frame!

Hi Hb,
I will definitely try your solution shortly.Alloy post in carbon frame- vs-carbon post in tit'm frame,much the same situation really.Thank you for your promt and helpful response.I will let you know how I get on.

Lemag

I have a carbon seatpost in my alu MTB frame. I used something like this (I think) for grip but also to avoid finding myself in your situation. So far so good but it's early days yet. If you manage to get yours out then I'm sure that there's something Holyboy or others could recommend for you to do/use to avoid finding yourself in the same situation again.

Good luck wih it.

minterno

some very hot water applied to the titanium only might also help by expanding the metal a little,regards

Holyboy

Lemag wrote: »

I have a carbon seatpost in my alu MTB frame. I used something like this (I think) for grip but also to avoid finding myself in your situation. So far so good but it's early days yet. If you manage to get yours out then I'm sure that there's something Holyboy or others could recommend for you to do/use to avoid finding yourself in the same situation again.

Good luck wih it.

Yes indeed, some kind of carbon assembly compound should be used to try to avoid situations like this also I always recommend removing cleaning and re-applying said compound about once every two weeks or so.

Lawr

Hot water. Boil the kettle. Carbon doesn't expand, but metal does. I couldn't believe how easily the post was removed after pouring boiling water on the seat tube. I didn't use any greases or compounds or anything else when reinserting it, knowing that a little hot water will allow its removal and a tight fit is really what I want in the interim.

Lemag

Lawr wrote: »

Hot water. Boil the kettle. Carbon doesn't expand, but metal does. I couldn't believe how easily the post was removed after pouring boiling water on the seat tube. I didn't use any greases or compounds or anything else when reinserting it, knowing that a little hot water will allow its removal and a tight fit is really what I want in the interim.

This may have worked for you but if the Aluminium seatpost were to expand with heat would it not do so inwards as well as outwards and hence the problem might be exacerbated? I presume that if your method was the ultimate solution then the various cycling forums wouldn't have as many threads on complicated seatpost-ectomies (spelling?).

tomasrojo

Lemag wrote: »

This may have worked for you but if the Aluminium seatpost were to expand with heat would it not do so inwards as well as outwards and hence the problem might be exacerbated?

I don't know about in the case of titanium or aluminium seat tubes, but a ring of metal doesn't necessarily expand inwards and outwards equally. If it did, the ball and ring experiment in physics wouldn't work.

http://sites.google.com/site/sed695b/projects/demonstration-equipment/expanding-ball--ring--thermal-expansion

A metal ball fits through a hole in a ring. If the ball is heated or the ring is cooled, it does not fit anymore.

If a metal plate containing a hole is heated then the whole plate will expand including the hole.

jimbobaloobob

i keep sachets of vinegar in the tool box for situations like that OP.

Pour it on and let it sit for a while.

Lawr

Lemag wrote: »

This may have worked for you but if the Aluminium seatpost were to expand with heat would it not do so inwards as well as outwards and hence the problem might be exacerbated? I presume that if your method was the ultimate solution then the various cycling forums wouldn't have as many threads on complicated seatpost-ectomies (spelling?).

Try it. It works. I did it again yesterday when I decided to raise my seat a smidge. My seat was stuck. I poured boiling hot water over the seat tube. Voila. If you want to reason it out before trying it and base your decision to try it on your untested reasoning, feel free to be frustrated. If you want to explain why people keep asking about how to deal with the problem, ask yourself how long it took you to test the hypothesis you reasoned would not work.

cython

Lawr wrote: »

Try it. It works. I did it again yesterday when I decided to raise my seat a smidge. My seat was stuck. I poured boiling hot water over the seat tube. Voila. If you want to reason it out before trying it and base your decision to try it on your untested reasoning, feel free to be frustrated. If you want to explain why people keep asking about how to deal with the problem, ask yourself how long it took you to test the hypothesis you reasoned would not work.

To understand how it works, just picture if what would happen if the tubing had been manufactured by cutting out the middle of a solid rod, so that you had the tubing, and a narrower rod that had been in the middle of the tube. If you place the rod back within the tube, and heat the two, were the tube to expand inwards, it would rupture as the inner rod expanded outwards, but because what actually happens is that the opening in the tubing has the same rate of expansion as the outer wall, the hole expands at the same rate as a cylinder of the same material would.

Thermodynamics, both a blessing, and a headf*ck!

Eamonnator

You've given me a headache. I'll have to go out on my bike now to clear my head.!!!!

Lemag

Eamonnator wrote: »

You've given me a headache. I'll have to go out on my bike now to clear my head.!!!!

It expands like this


rather than like this