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  1. #1
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    Stuck Seatpost...as in really stuck

    Hey all,
    I have a problem that's been discussed plenty of times, but none of the methods have worked. I have a carbon fuji team frame that is stuck with an aluminum post. I brought my bike to a bike shop and they tried putting the post on a vice grip and twisting the frame, and that hasn't done anything at all, other than gouge up the seatpost. Lately i've been shooting pb-blaster down the edges of the seattube, but that has not worked.

    I'd definitely try to shoot the pb-blaster or coke up the seattube via the bb shell and let it sit, but that would require me be off the bike for a few days/weeks, and that's not quite an option for a long time seeing as it is road season now. Most of what sheldonbrown's site isn't very much help, and most of the success stories i've read came from non-carbon frames. Any ideas?

  2. #2
    sch
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    The obvious is 1) stay with the present post unless damaged beyond use or risk
    2) new frame
    All techniques assume a fairly rigid, impervious frame material which in this circum-
    stance CF is not. Depending on how long the buried part of the post is, one can
    imagine a large drill perhaps 0.03 (1/32") smaller OD than the ID of the seat tube,
    an externally clamped guide tube long enough to center the drill in the bore and a
    cautious drill out of the seat post after cutting to near the top of the seat tube.
    This assumes a cylindrical seat tube and a long enough extension for a guide to be
    clamped to. A smaller ID seat post can then be fitted with a sleeve. IE drill out
    a 27.2 OD post to 26 mm and use a 25mm post with sleeve or some variant.
    Sleeve would be permanent. Post would not be sexy. More difficult with not
    cylindrical seat tubes, but the seat post itself could be used as a guide tube clamp.
    Such a drill would run $40-70 or so and a machine shop access to make guide tube.
    Last edited by sch; 02-09-09 at 10:34 PM.

  3. #3
    Senior Member cheg's Avatar
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    I had an aluminum seatpost stuck in a steel frame. I tried PB blaster, dry ice in on the inside and heat on the outside, and lots of force. I finally snapped the head of the post off when I was trying to turn it out by clamping the post in a vice and twisting the frame. I ended up getting the seatpost (and the stem) bored out by a local frame maker with a good drill press then honing out the tubes with a brake cylinder hone. It's not a delicate operation. Don't think if I would try that process on carbon fiber frame that I cared about riding again.

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    I'm not sure using PB Blaster on a carbon frame is such a good idea, as it may affect the resin matrix.

  5. #5
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    The hack saw and peel method should still work. It'll destroy the post but it should work, you should be able to do it yourself, and it should not damage your frame if you are careful. I would do that before trusting someone to bore the post out of my frame with a drill bit which is probably the worst common device known to man for making really precise holes. If you do have to have it drilled out, find a shop with a reamer.

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    sch
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    Hacksaw and peel method assumes you won't mind nicking the inside of the
    seat tube and that you can do a little prying of the dismembered seat post
    away from the inside of the seat tube, neither of which is a great idea with
    a CF seat tube, especially in an area of severe stress. OTOH a 'little damage'
    might be mended with an insert bonded to the inside of the seat tube. Works
    for head tubes and CF, though head tubes are a good bit more stout.

  7. #7
    Peace and bicycle grease! une_vitesse's Avatar
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    i once had that prob with an al seatpost in a steel frame. i tried everything, to no avail, until i poured ammonia up the seattube and was able to twist the sp out without too much difficulty. ammonia apparently disolves aluminium oxide, so you may want to try that, as long as it doesn't react with the epoxy of you cf frame...
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  8. #8
    Map maker cbchess's Avatar
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    heat frame, chill seat post +1
    ammonia +1

  9. #9
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    Quote Originally Posted by une_vitesse View Post
    i once had that prob with an al seatpost in a steel frame. i tried everything, to no avail, until i poured ammonia up the seattube and was able to twist the sp out without too much difficulty. ammonia apparently disolves aluminium oxide, so you may want to try that, as long as it doesn't react with the epoxy of you cf frame...
    Thanks for the input. I'd like to try the ammonia, but there are a few problems: 1)I don't know where to find it, and 2)i dont know if it reacts with the resin. Anyone have any information on this?

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    I once had one that was really good and stuck - none of Sheldon's list of 15 things worked. I finally got it free with no damage, but this was a steel frame/aluminum post - so take this with a grain of salt as I have no experience with CF. Some shops have a jig on their repair stands that clamps through the BB. You have to remove the crank/bb and then the bb shell slips over this threaded mandrel and a plate threads on to clamp it. Then, with the frame clamped and a crappy seat mounted, and after working every conceivable solvent/PB Blaster/liquid wrench/oil from both the top and bottom (via the holes for the water bottle cage and finally the bb), I was able to use the seat as a lever arm and just twist it free, bit by bit, back and forth, applying more Blaster as I went. That was my success story -- take it for what it's worth -- I'm not sure that a cf frame can stand up to that kind of torque.

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    You can buy ammonia at any hardware store or home center. Parsons is a common brand. Not sure how it reacts with cf.

  12. #12
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    A lot of household cleaners also have large amounts of ammonia although I'm also unsure as to what it would do to the resin. The hacksaw method can be done without ever nicking the frame as the seat post will tear when it gets really thin. Also, does your carbon frame have an aluminum sleeve in it that the seat post inserts into or is it actually bare carbon in there?

  13. #13
    DRF aka Thrifty Bill wrk101's Avatar
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    Should be able to buy ammonia at Walmart. Pretty common house cleaning material.

  14. #14
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    Wait - is ammonia going to help at all in a carbon frame? My guess is no.

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    Find a really big freezer?

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