Carbonfibre seatpost stuck in aluminium frame

[DoubleDee]

Anyone have any advice to loosen carbonfibre seatpost from aluminium frame without doing any damage to frame or seatpost? Thanks

[kennyg]

take the clamp off first...

 

if that doesnt help, try heating the alu gently, with a torch, then try a rubber hammer to caress her out.

[gummibear]

take the clamp off first...

 

if that doesnt help, try heating the alu gently, with a torch, then try a rubber hammer to caress her out.

 

I would try a little Q20 first.

Leave it overnight and try tomorrow.

[Tubehunter]

Be glad its not an alu seatpost in a carbon frame! VERY GLAD!!

[DaLoCo]

Use a large flat screwdriver. Insert the tip in the groove on the frame and twist so it opens the frame.

[gummibear]

Be glad its not an alu seatpost in a carbon frame! VERY GLAD!!

 

When you get it out buy some carbon paste before you put it back in.

[V12man]

Use a hairdryer not a torch initially - torch will burn the paint if you do not have good control and practice.

 

I would just use a slide impact hammer to pop it out the top after some anti corrosion oil for a day or two (combined with some heating)

[Johan Bornman]

OK, now that you've tried everything and blistered your paint, cracked the frame, bust a gut and cursed a bit, do it the right way.

 

Aluminium oxide is the culprit. The post was probably greased before inserted. Water gets in there, forms an emulsion with the grease and then proceeds to corrode the alu. Aluminium oxide is a larger molecule than an alu molecule and therefore the alu oxide crystals expanded inwards, trapping the post. No chemical process will reverse this and no penetrant will work. Force may or may not work.

 

Saw the seatpost off, about 25mm above the top of the seat tube.

 

Now insert a hacksaw blade with the one end wrapped around a cloth and proceed to saw the seatpost lengthwise until you touch the frame. It is a long, laborious job but gets shorter with beer. Be patient, do a decent job and don't inhale that horrible carbon dust and don't get carbon splinters in your fingers.

 

Once the seatpost is now sawn through, tap it with a mallet and it will pop right out.

 

The reason why it can now get out so easily is because the corrosion doesn't bond it, but just expands. With a groove in there it can expand inwards and come loose.

 

PS - I notice no-one has suggested the Coca Cola remedy yet? C'mon, get with it!

[gummibear]

PS - I notice no-one has suggested the Coca Cola remedy yet? C'mon, get with it!

 

I don't waist Coke,rather use it in my Brandy.

[Scooterza]

OK, now that you've tried everything and blistered your paint, cracked the frame, bust a gut and cursed a bit, do it the right way.

 

Aluminium oxide is the culprit. The post was probably greased before inserted. Water gets in there, forms an emulsion with the grease and then proceeds to corrode the alu. Aluminium oxide is a larger molecule than an alu molecule and therefore the alu oxide crystals expanded inwards, trapping the post. No chemical process will reverse this and no penetrant will work. Force may or may not work.

 

Saw the seatpost off, about 25mm above the top of the seat tube.

 

Now insert a hacksaw blade with the one end wrapped around a cloth and proceed to saw the seatpost lengthwise until you touch the frame. It is a long, laborious job but gets shorter with beer. Be patient, do a decent job and don't inhale that horrible carbon dust and don't get carbon splinters in your fingers.

 

Quality answer! Nice! The other answers were logical but this is the kind of answer you get from someone who has clearly got experience!

[MTBer wannabee]

Quality answer! Nice! The other answers were logical but this is the kind of answer you get from someone who has clearly got experience!

 

Or maybe did not read the original question. The OP wanted a solution without damaging the frame or seatpost.

So I guess the correct answer is that it cant be done.

Edited October 4, 2012 by MTBer wannabee

[urbanroyal]

Dude ...I'll just twist it at the saddle till it either comes loose or breaks ... :-)

[Li Mu Bai]

take the clamp off first...

 

if that doesnt help, try heating the alu gently, with a torch, then try a rubber hammer to caress her out.

DONT USE A TORCH, jeez. And how can you take the clamp off first? you can loosen it yes.

 

I had the same problem before. seatpost stuck fast. Called JB late on a sunday night for advice. He suggested I use boiling water from a kettle poured over the top of the frame where the seatpost protrudes. Twist and wiggle the seatpost using the saddle for leverage, untill it sticks fast again. repeat the process. it is slow and you will use many kettle fulls of hot water, but eventually the seatpost comes free, 1-2mm at a time. The carbon and the alum have different co-efficients of expansion. Took me over 4 hours but I got it out and didnt have to cut anything.

Clean out the seat tube, removing any grease/wax left behind.

DO NOT LUBRICATE YOUR SEATPOST/SEAT TUBE CONECTION WITH GREASE! it turns waxy after a while and then the seatpost gets stuck. Make a habit of removing your seatpost every once in a while to make sure the same doesnt happen again.

Edited October 4, 2012 by Li Mu Bai

[Sawdust]

I used Coke. Frame upside down. Filled with coke, left in the shower overnight. Fitted a saddle and it came loose.

[FrankTank]

Fortunately, aluminum oxide can be dissolved like magic by using ammonia. Worked twice for me in the past. Submerge in ammonia for a day or two.

 

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

Edited October 4, 2012 by FrankTank

[Vetseun]

Wont some spook piss make it come loose?