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Old 09-27-10, 01:17 PM   #1
MrAloc
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Stuck seatpost problems.

Hello,

First of all, many thanks to all very knowledgeable users who through their posts have provided me with many good tips and advice.

Now on to my problem, a stuck aluminium seatpost (27,2 mm Dura-Ace) in a carbon frame. The seatpost is inserted about 14 cm in the frame.

When problem was first encountered I never imagined the headaches this would cause. I first tried twisting/pulling with all the power I could come up with. Tried to use saddle for leverage, only resulting in top bit rotating in the post (press fitted clamp bit).

By this stage I was getting frustrated and moved on to chemicals, etc. Some of which I should probably have avoided due to CF (WD40, lubricating oil, Coca Cola and ammonia). These where all applied through waterbottle bolthole using a "pipette" but without success.

I then had to bite the bullet and sacrifice the nice post, which I have been cutting/filing for about two weeks. I can't believe how tough this post is. The outer shiny layer will not break and I do not want to risk the frame, any advice?

Would say about 50% of post material has been removed, problem with hacksaw blades is to make the cut equally deep all the way down. Post has been cut/filed down in places 3/4 around the post.

Atleast I am a stubborn bastard and in the worst case scenario I will end up filing it all out, will probably take another couple of weeks.

Already at this stage I have ended up with LOADS of filings in the seattube which I plan to remove by turning frame upside down/hoovering out. Could this have damaged my Dura-Ace BB (BC 1,37 68)? Will this have to be removed and cleaned/replaced?

If/when post is removed it will be replaced with carbon post (carbon in carbon), what is the best to do regarding grease/copper paste? I never want to have to experience this again.

Any advice will be greatly appreciated, I can't wait to get back on the roads.

Last edited by MrAloc; 09-27-10 at 02:26 PM.
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Old 09-27-10, 03:07 PM   #2
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I understand how you feel about using chemicals and CF , but the best one to use here was /is ammonia, not what you buy at the supermarket but at the hardware store, it stonger stuff, which would of breaking the bond and allow the post to come out. it should have been apply at the top of the fame where the post goes in ,tap with a rubber hammer to get it to work it way in. as long you clean it out no it wouldn't hurt the BB. you will need to lube the post with something like paste
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Old 09-27-10, 03:43 PM   #3
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Originally Posted by bikeman715 View Post
I understand how you feel about using chemicals and CF , but the best one to use here was /is ammonia, not what you buy at the supermarket but at the hardware store, it stonger stuff, which would of breaking the bond and allow the post to come out. it should have been apply at the top of the fame where the post goes in ,tap with a rubber hammer to get it to work it way in. as long you clean it out no it wouldn't hurt the BB. you will need to lube the post with something like paste

I tried to apply from top as well but it didn't seem to want to work it's way in (very tight fit). Obviously apply from beneath would require quite some quantity to allow hollow post to fill up before it making it's way in-between post and frame.

In the UK it is difficult to get hold of ammonia, not sure why? Belive it could be used in making explosives? Do not think drug usage is the reason? Managed to get some 9.5% strength ammonia after trying several chemists and as far as I understand anything above 10% won't be available.

I have investigated grease, paste, etc. usage on carbon and many people seems to think this brakes the CF down?

Anyway, at this stage it seems to be a problem for the future but will seek advise at LBS.

Thanks for your answers.
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Old 09-27-10, 03:44 PM   #4
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I tried to apply from top as well but it didn't seem to want to work it's way in (very tight fit). Obviously apply from beneath would require quite some quantity to allow hollow post to fill up before it making it's way in-between post and frame.

In the UK it is difficult to get hold of ammonia, not sure why? Belive it could be used in making explosives? Do not think drug usage is the reason? Managed to get some 9.5% strength ammonia after trying several chemists and as far as I understand anything above 10% won't be available.

I have investigated grease, paste, etc. usage on carbon and many people seems to think this brakes the CF down?

Anyway, at this stage it seems to be a problem for the future but will seek advise at LBS.

Thanks for your answers.
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Old 09-27-10, 04:01 PM   #5
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I Have a Steel frame with an aluminum post stuck in mine. I tried a hole thought the seat post with another shaft though that to get leverage in twisting it out. This ended up snapping the old seat post and now i have a bigger problem. I was considering spraying the seat post with some CO2 to cool it down and try pulling it out and was curious if anyone has tried that. Not sure if its the best option for the carbon fiber.
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Old 09-27-10, 04:49 PM   #6
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Originally Posted by SteelsReal View Post
I Have a Steel frame with an aluminum post stuck in mine. I tried a hole thought the seat post with another shaft though that to get leverage in twisting it out. This ended up snapping the old seat post and now i have a bigger problem. I was considering spraying the seat post with some CO2 to cool it down and try pulling it out and was curious if anyone has tried that. Not sure if its the best option for the carbon fiber.
It has all been tried. Go to google, search: stuck seatpost site:bikeforums.net

You will find hundreds of threads on this topic. At some point, you will have exhausted every option but cutting it out. Hopefully it will come out before then.
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Old 09-28-10, 06:24 PM   #7
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Quote:
Originally Posted by SteelsReal View Post
I Have a Steel frame with an aluminum post stuck in mine. I tried a hole thought the seat post with another shaft though that to get leverage in twisting it out. This ended up snapping the old seat post and now i have a bigger problem. I was considering spraying the seat post with some CO2 to cool it down and try pulling it out and was curious if anyone has tried that. Not sure if its the best option for the carbon fiber.
Yup, I tried that and it worked to get my aluminum quill stem unstuck from the steel steering tube on my bike.
But I did not exactly use CO2 to cool it as you suggested, but a product called "Freeze-Off" from a company called CRC. It comes in a large spray can and can be bought at many auto parts stores. Not sure if they use CO2 in it but it sure really cools down the metal you spray it on. They also combined the cooling agent with some sort of penetrant liquid to help things out.
It released my stem after weeks of trying to get it out with Liquid Wrench, PB Blaster and all other sorts of penetrants plus prodigous hits from my deadblow mallet at appropriate places. It worked within barely minutes of applying it as it shrank the Aluminum stem away from the steel steering tube, cracking the corrosion and letting the penetrant lubricant in between the two parts. I even saw bubbles coming out of the seam between the two as the stuff worked it's way down into the crack on the visible white Fe/Al oxide. A couple of medium force whacks with my dead blow mallet and the stem started moving and was free seconds later. Also used it on my then seized up BB cup lockrings and they also released within seconds. I also did not have luck with PB blaster in that area.
Trick always was to aim the spray where you will get differential shrinkage of the material from the freezing. That causes the corrosion to break apart between the tow components and start to release them from each other.
One thing that concernds me is the effect of freezing on the resin used on CF frames. It might cause it to get brittle enough that you might end up cracking things if you apply force to it. So check on that before you consider any freezing solutions.

Good luck! Hope you eventually get that seatpost off.

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Old 09-28-10, 08:10 PM   #8
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CF airplanes routinely operate over temps from -60F to 120F without difficulty.
May be they use 'special stuff', but likely not all that special. OTOH freezing
relies of differential temp coefficients of expansion, and that bears looking into
for CF vs AL. Steel versus AL are different enough for this to be potentially
useful.
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