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Stuck seatpost - ally in carbon frame

snellgrovesnellgrove Posts: 171
edited November 2009 in Workshop
Hello all,

Anyone ever had the misfortune of an aluminium seatpost stuck inside a carbon frame?

I've just got fed up of it, and booked it into my preferred LBS and I asked about what should happen if the frame were to go pop and they talked about signing a disclaimer saying it's not their fault etc! :shock: I'm a bit scared by this, as I don't want to fork out for a new bike should the shitty £10 seatpost that's currently in it cause the frame to go bang :(

Anyone know if the bike is likely or unlikely to survive, or is it entirely unpredictable!

:(

Posts

  • k2riderk2rider Posts: 575
    if they cut the post out using a hacksaw then they should be able to save the frame, twisting wouldnt do the c/f any good whatsoever and should be avoided, my own preffered method of getting an alloy post out of a carbon frame would be to use an adjustable reamer and ream out the alloy post.
    who cares?
  • jairajjairaj Posts: 3,009
    Have a chat with the shop and make sure they know what are suitable techniques for getting a stuck post out of carbon frame.

    If all they can say is brute force and ignorance then I'd go somewhere else. but if they are aware of the complications that come with the task in hand then hopefully they'll do it right?
  • flickstaflicksta Posts: 157
    If you carefully chip away at the carbon clamping the seatpost you should be able to extract it completely undamaged


    :wink:
  • will3will3 Posts: 2,173
    flicksta wrote:
    If you carefully chip away at the carbon clamping the seatpost you should be able to extract it completely undamaged


    :wink:

    Actually carbon burns quite well, so you could just set light to the frame and pull the seatpost out of the ashes. Might knock the temper out of the aluminium a bit, though.
  • El TelEl Tel Posts: 63
    I've seen suggestions that household ammonia will dissolve the corrosion that has probably formed on your aluminium seatpost. Remove the bottom bracket and turn the frame upside down, plugging any holes in the seat tube, and then squirt the stuff in and leave it for a couple of hours. Then rinse things out and try removing the post again.
    If you can, try tapping under the top of the seatpost to loosen it, as well as a bit of twisting (but not too much, with a cf frame). Use a bit of cf assembly compound when you put the new one in. It won't hurt the cf and it should resist future corrosion.
    El Tel
    Ribble Nero Corsa
  • ride_wheneverride_whenever Posts: 13,279
    Or use coke, which is great for loosening aluminium, and is probably a bit safer for the frame.
  • rakerake Posts: 3,204
    edited March 2010
  • I used some ammonia on a alu post stuck in an alu frame. This is what I did:
    Used an old toothbrush (or your current one if you want whiter teeth) and "dab" into the top of the frame/seatpost. Wait 10 mins then do the same again. Then wait 10 mins and TWIST the saddle and it should come free. Use a liberal amount i.e. an egg cup full each time.

    PS I'm not sure what ammonia does to Carbon so it's a good idea to give it all a wash down afterwards. Also wear safety glasses and try to do it outdoors or be ready to develop a hole in the top of your head due to the fumes.
  • Anyone ever had the misfortune of an aluminium seatpost stuck inside a carbon frame?


    Liquid nitrogen or a carbon dioxide fire extinguisher. Either can be used to freeze the alloy seatpillar (which should shrink just enough) then put seat pillar in vise and twist and maybe if you are lucky. Otherwise abandon.
  • Cooling it could work, but i'd be worried about increasing the brittleness of the frame and shearing the seattube. I'd probably just cool the seatpost, stick one end in a dewar of liquid nitrogen and it should shrink enough to twist it free carefully.
  • Or try something like : http://loctitefreezeandrelease.com/
  • rake wrote:
    @will3. one of carbon fibres properties is that it doesnt burn

    Most Resins will burn though.
    spamspam.jpg
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