HELP! "Frozen" seatpost!!!

Discussion in 'Cycling Equipment' started by Mike, Apr 2, 2003.

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  1. Mike

    Mike Guest

    Well, I've finally encountered one I couldn't crack. Aluminum alloy seatpost stuck in an older Aegis
    carbon frame. Looks like there's a steel insert surrounding the post, 'cause I can see some rust.
    Usually, if after trying various brands of "rust-busters" and WD-40 with no success, I take out the
    propane torch and heat the post, let it cool, and out it comes. I've reasoned that simply heating
    and therefore "expanding" the post, only to let it cool again and contract, would buy me just enough
    "space." Combine that with differing expansion coefficients and rates, dissimilar metals, etc.,
    etc., and you "break" the bond. I'm no engineer, but it has never failed me before. Well, not this
    time, even after trying all of the above repeatedly. LAY YOUR BEST RECIPE ON ME! Thanks, Mike
     
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  2. S. Anderson

    S. Anderson Guest

    "Mike" <[email protected]> wrote in message
    news:[email protected]...
    > Well, I've finally encountered one I couldn't crack. Aluminum alloy seatpost stuck in an older
    > Aegis carbon frame. Looks like there's a steel insert surrounding the post, 'cause I can see some
    > rust. Usually, if after trying various brands of "rust-busters" and WD-40 with no success, I take
    > out the propane torch and heat the post, let it cool, and out it comes. I've reasoned that simply
    > heating and therefore "expanding" the post, only to let it cool again and contract, would buy me
    > just enough "space." Combine that with differing expansion coefficients and rates, dissimilar
    > metals, etc., etc., and you "break" the bond. I'm no engineer, but it has never failed me before.
    > Well, not this time, even after trying all of the above repeatedly. LAY YOUR BEST RECIPE ON ME!
    > Thanks, Mike

    You heated a post in a carbon frame with a propane torch?? Hmmm..Well, nevertheless, you can try
    cutting off the top the seat post to a point about an inch or 2 above the seat lug. Then you can
    take a hacksaw blade and wrap a rag around it and cut the seatpost longitudinally down the seat
    tube. Cut it into four pieces and usually you can eventually tap it out. You obviously are buying a
    new seat post though!

    Good luck,

    Scott..
     
  3. This can be a real bitch because Aluminum has a greater coefficient of expansion than steel. Heating
    an aluminum tube inside a steel one will only make it tighter. Cooling an aluminum tube inside a
    steel one will make it looser. I doubt that you can cool it enough to make a difference.

    You might try carefully heating the steel frame and torquing the seat tube at the same time (like
    trying to unscrew it, and alternating clockwise/counterclockwise) with a pipe wrench or channel lock
    pliers. This should help if the parts are corroded together, or they have some heavy tar or pitch
    between them.

    If this fails, a mild acid, like vinegar put between the tubes may help. I would consider this an
    absolute last hope type thing.

    Let us know how it turns out.

    Good luck Ernie

    Mike wrote:

    > Well, I've finally encountered one I couldn't crack. Aluminum alloy seatpost stuck in an older
    > Aegis carbon frame. Looks like there's a steel insert surrounding the post, 'cause I can see some
    > rust. Usually, if after trying various brands of "rust-busters" and WD-40 with no success, I take
    > out the propane torch and heat the post, let it cool, and out it comes. I've reasoned that simply
    > heating and therefore "expanding" the post, only to let it cool again and contract, would buy me
    > just enough "space." Combine that with differing expansion coefficients and rates, dissimilar
    > metals, etc., etc., and you "break" the bond. I'm no engineer, but it has never failed me before.
    > Well, not this time, even after trying all of the above repeatedly. LAY YOUR BEST RECIPE ON ME!
    > Thanks, Mike
     
  4. Ronald

    Ronald Guest

    http://www.sheldonbrown.com/stuck_seatposts.html

    "Mike" <[email protected]> wrote in message
    news:[email protected]...
    > Well, I've finally encountered one I couldn't crack. Aluminum alloy seatpost stuck in an older
    > Aegis carbon frame. Looks like there's a steel insert surrounding the post, 'cause I can see some
    > rust. Usually, if after trying various brands of "rust-busters" and WD-40 with no success, I take
    > out the propane torch and heat the post, let it cool, and out it comes. I've reasoned that simply
    > heating and therefore "expanding" the post, only to let it cool again and contract, would buy me
    > just enough "space." Combine that with differing expansion coefficients and rates, dissimilar
    > metals, etc., etc., and you "break" the bond. I'm no engineer, but it has never failed me before.
    > Well, not this time, even after trying all of the above repeatedly. LAY YOUR BEST RECIPE ON ME!
    > Thanks, Mike
     
  5. Gizmomaker

    Gizmomaker Guest

    Mike wrote:

    > Well, I've finally encountered one I couldn't crack. Aluminum alloy seatpost stuck in an older
    > Aegis carbon frame. the above repeatedly. LAY YOUR BEST RECIPE ON ME! Thanks, Mike

    Go through the archives... 100s of posts on this. Taking the wheels off, turning it upside down and
    holding the seatpost in a large vice while twisting the whole frame works for me. Preceded by
    pouring WD40/coke (the drink)/various other substances through the wb brazeon screw holes in the
    seat tube or via the BB. The joy of that just perceptible 1 degree bond breaking twist is superb.
     
  6. Mike

    Mike Guest

    First, thanks for the ideas and encouragement.

    How I got it out:

    Since nothing else worked, I had to resort to "mechanical removal." I cut off the post at the
    highest point possible, before it tapered to "aero." Whoa! This baby had 5mm thick sidewalls
    (eventually tapering down to 3mm at the post bottom, I would see later. It was an old Shimano 600 or
    Dura-Ace). There would obviously be no "curling this thing in on itself" after making a single
    vertical cut through the post sidewall--not at over 3mm thick.

    So I made SIX radial cuts (sort of like slicing a pizza), using a Sawzall WITH EXTREME CAUTION,
    being careful not to cut completely through the post. I then deepened two of adjacent cuts further
    using a keyhole-type saw that's essentially a handle which accepts Sawzall blades (invest a few
    bucks in one of these--it's very handy, and it beats the heck out of trying to jerry-rig a hacksaw
    blade for these kinds of jobs).

    I then punched/pried the one section inward toward the post center. Once it was out of the way, it
    was relatively easy to collapse the post in on itself by squeezing it down to a smaller diameter,
    and out it came. No damage to the frame, and about an hour total for the job.

    Patience really was a virtue here, and having the right tools helped a lot, too (when you need a
    Sawzall, there's nothing that beats a Sawzall).

    Of course, the seatpost I trashed was a 26.8, since I have only about a half-dozen 27.2's in stock!

    Thanks again. Hope this helps somebody else in the future.

    Mike

    [email protected] (Mike) wrote in message
    news:<[email protected]>...
    > Well, I've finally encountered one I couldn't crack. Aluminum alloy seatpost stuck in an older
    > Aegis carbon frame. Looks like there's a steel insert surrounding the post, 'cause I can see some
    > rust. Usually, if after trying various brands of "rust-busters" and WD-40 with no success, I take
    > out the propane torch and heat the post, let it cool, and out it comes. I've reasoned that simply
    > heating and therefore "expanding" the post, only to let it cool again and contract, would buy me
    > just enough "space." Combine that with differing expansion coefficients and rates, dissimilar
    > metals, etc., etc., and you "break" the bond. I'm no engineer, but it has never failed me before.
    > Well, not this time, even after trying all of the above repeatedly. LAY YOUR BEST RECIPE ON ME!
    > Thanks, Mike
     
  7. On 4 Apr 2003, Mike wrote:
    > How I got it out:

    > Thanks again. Hope this helps somebody else in the future.

    What a timely post! Yesterday I was promised (for free, of course) a very nice Colnago frame with a
    stuck post and I was just figuring out on the best way to do it.

    Next week, my turn.

    Sergio Pisa
     
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