Seat post stuck in frame! Any clever ideas?

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  • Seat post stuck in frame! Any clever ideas?
  • simbob
    Member

    Got a new saddle recently, slightly different to the old one, went to raise the Seat post only to find it’s stuck in the frame! Problem is it’s a carbon post and aluminum frame so can’t grip it too tight for fear of cracking it.

    So far I’ve tried: Lashings of WD40, Heating up frame (only with a hair dryer mind!), old inner tube wrapped around and mole grips clamped over, same process with stilson type (self tightening) wrench, but it won’t budge, there is approx 8″ of tube inside the frame so proving very difficult to shift. Also, the seat mounting bracket has come detached through me trying to twist it out, but that does mean access to the inside.

    I don’t want to drill a hole through it to insert a lever, but i can’t see any other way, although there’s no guarantee this will work either, and i don’t really want to whack it in any further in case it just ends up wedged in further. Can’t get at it from below either.

    Anyone got any clever ideas or know of a tool i can push down inside that will allow me to whack it upwards?

    Do you reckon this could be a warranty claim?

    Premier Icon njee20
    Subscriber

    Do you reckon this could be a warranty claim?

    No chance.

    I’d try Plusgas rather than WD40, this is likely to be a colossal headache though, just to forewarn you…

    Putting seatpost in vice and twisting frame is a good option. The odds of retaining a useable seatpost and frame are extremely unlikely!

    Premier Icon darrenspink
    Subscriber

    LBS to see if they can do it…could save you a lot of cash.

    mylofitz
    Member

    Sounds daft but have you tried riding it? Your body weight and a few bumps may be enough to break the bond between the carbon and the alu frame. Better than applying strong twisting forces from the off.

    oldejeans
    Member

    What would Sheldon do?

    fozzybear
    Member

    Can you get the Bb out?
    Tip it upside down and Pour something into the tube?
    Coke maybe 😉

    Premier Icon Suggsey
    Subscriber

    Blind bearing puller? I would go for the big bog off hammer and knock it downwards to break the bond, face it the post will be knackered anyway !
    Also second the plusgas approach over night as opposed to WD40.

    Problem with a carbon is oil/wd40/plusgass etc tends to expand the resin binder and makes it worse. I assume corrosion/oxidization of the aluminum frame has caused the two to stick. Ammonia dissolves aluminum oxide, used to be able to buy it from the chemist if not a drain cleaner with ammonia as a base should work. It won’t penetrate as well as oil so best to take the seat off and tun it upside down and soak it overnight or longer in a jar of it.

    Another thing to try is to turn the seat post into a puller. Slacken off the seat cut a couple of bits of plate/bar to fit tight between the seat rails and the top edge of the frame seat tube then tighten up the seat, the rails will push down on the frame tube and may break the seal.

    mayan
    Member

    I had the same problem.

    Build a collar of plasticine or similar around the seat clamp area (if there is a clamp or bolt, then take it off / out completely – leave the seat on tho’) Form the plasticine so that it makes a kind of dam / reservoir around the post / seat tube junction and fill it with coke. Keep the bike upright, and keep topping it up. It will probably take a few days….top it up each morning and each evening. The aim is to keep coke trickling down into the gap between frame and post, apparently the galvanic corrosion is dissolved by the coke.

    When you’ve run out of coke and / or patience, turn the bike upside down, clamp the seat in a vice / workmate etc then using the frame as leverage, twist the thing back and forth. If it works, it will probably make a horrible noise like you’ve ripped the frame in half as the seal breaks, then you’ll need to pull and twist it out at the same time.

    When you have the seat post out, throw it in the bin and put in a proper metal one!

    Good luck!

    tonyplym
    Member

    Something that has worked for me – wedge an appropriately shaped bit of wood under the saddle (as close as you can get to being aligned above the seatpost), or hold it to the seatclamp, then take a blunt large diameter drill bit and pop it into your hammer drill. Put drill on “hammer only” (if available) or in reverse and “drill + hammer”, then apply the drill bit firmly upwards to the block of wood aligning the drill as close as you can to the line of the seatpost. If you’re lucky the high frequency hammer action will get things moving. Also works using an air chisel . . . .

    Premier Icon Zaskar93
    Subscriber

    Happened to me with a Thomson (non carbon) post in my Heckler frame a couple of years ago.

    Got it out undamaged, apart from a couple of scuffs but perfectly useable too.

    [From previous posting]
    Been spraying WD40 down the inverted frame [bottom bracket removed and seat post and tube made up with old inner tube and tape] for days and then on Saturday I plugged it and filled it with diesel and left it to soak. Stuck it in the bench vice yesterday and got it turning in the frame and then popped an old saddle on and my wife gave me a hand to screw it out of the frame. Some of the black anodizing has come off the inserted part but that’s a not a problem. Cleaned it up, blathered it with Waxoyl, car body underseal to avoid any other kind of corrosion, and popped it back in.

    Hope that helps and best of luck.

    crispycross
    Member

    Cut the seatpost off a short distance above the frame, maybe 50 mm, so you’ve got something to grab. Poke a hacksaw blade down the seatpost and cut a slot in it from the inside. Cut more slots if necessary. Worked for me once.

    Premier Icon nedrapier
    Subscriber

    from the last time:

    nedrapier – Member
    I tried a hairdryer, I reckon boiling water’s better.

    My name’s Ed, I had a stuck seat post, and this is my story:

    – coca cola down the seattube over a weekend
    – forcing apart the clamp slot and spraying GT85 (I used the handle of a table knife in an adjutable spanner)
    – boiling water round the top of the seattube.
    – Once you’ve got it moving a bit, then comes the mighty heaving:
    – from the non-drive side of the bike – left foot in the downtube/seattube junction, heel of the right hand pushing the back of the saddle towards me, left hand on the nose, pulling out and twisting. I won about a millimeter of seatpost per quarter turn, then I had to return it to center for another twist n pull.
    – apply more boiling water when it starts to get trickier, every 3 or 4 quarter turns
    – repeat as necessary.

    wear gloves! I lost skin on 2 fingers and have a big blister in the palm of my hand.

    This was with a carbon skin post, but it’s all mechanical, except for the coke.

    Good luck!

    Not sure whether the coke did anything. The kettle is the winner, I reckon – way more heat transfer than similarly hot air from a hairdryer, and a heat gun is probably going to get you into paint and frame strength issues.

    soorgrapz
    Member

    Plusgas twice a day, a sacrificial saddle and the biggest rubber mallet you can muster!

    In between beatings leave the seatclamp loose and ride the life out it over the roughest terrain you can find.

    Premier Icon sandwicheater
    Subscriber

    Sacrifice three kittens twice daily. Should take a week all in all.

    Your welcome.

    Same problem as OP on a friends old Trek Road bike. Tried everything in the end had to destroy the carbon post then chisel remove the stuck bits out and carefully sand out the remaining carbon from the Alu seat tube. Never again, got splinters everywhere. Miserable Job.

    townydc
    Member

    Stilsons……..

    steve_b77
    Member

    It’s knackered already, just cut it out a bit at a time

    Premier Icon BadlyWiredDog
    Subscriber

    I just took a slightly seized carbon seatpost out of an alloy frame using Effeto Mariposo carbomove spray stuff. It seems pretty decent, though it didn’t manage to shift a carbon post sat in my old Voodoo Wanga steel frame, which was why I bought it in the first place.

    Might be worth a go.

    damascus
    Member

    Do you need to take it out? You could do all the above or you could just ride it as . Is

    Premier Icon deadkenny
    Subscriber

    Carbon + alloy – galvanic reaction and the two bond.

    I knew this with my c456 frame and the alloy post in the carbon frame, but I got lazy and stopped taking the seatpost out after rides. Result is recently it bonded together.

    Got it out eventually but took a hell of a lot of effort and attempts with 3-in-1 penetrating oil, fizzy liquids, heat, vice clamp post, repeat and leave to soak in various fluids. Eventually it was turning with enough effort to make my arms ache and the thing making a hell of a screech, but what I think finally got it loose was I tried a bottle of ski/board base cleaner. It’s basically a citric acid mixture.

    Now removed and the post was clearly eaten away. Filed down and cleaned up the carbon and alloy bits. Post goes in easy now, too easy even.

    Key thing is use some carbon paste. It will help keep the post in with less clamping force and reduces the galvanic reaction, and then also remove the post after rides. Especially after washing the bike.

    user-removed
    Member

    After trying most of the above I went for the hacksaw blade route. Took ages, hurt my fingers but is guaranteed to (eventually) work. I’d it’s properly bonded, you might need to scrape the strips off the inside of the tube with a scrrwdriver

    jordie
    Member

    Just buy the same saddle again no need to shift anything

    globalti
    Member

    Don’t waste your time squirting PlusGas or WD40 or any other so-called penetrating lube down, it won’t go. There’s no galvanic action between alloy and carbon; the problem is simply that aluminium oxide takes up more space than aluminium so has filled the space around the post and locked it solid. Don’t pour caustic or coke down, that could weaken the frame. Mechanical action is the only way to free it; put the post in a vice and twist the frame around it. Be prepared to sacrifice the post. Be aware that as soon as you start moving the post the aluminium oxide will build up in the gap and gall, so movement will become more difficult until you’ve freed a significant length of the post from the frame.

    soulboy
    Member

    I’ve had the same problem with a carbon post stuck in an alloy frame, Simbob, and the following method worked for me:
    Cut off the post an inch or so above the top of the seat tube. Using a chisel, create some longitudinal grooves running down the inside of the post, taking care not to cut right through the post and damage the inside of the seat tube. Using a combination of hammer, chisel and screwdriver, spit off layers of the carbon post, starting from the inside of the post, progressively working outwards. Because I was dealing with a long post, I needed a very long screwdriver towards the end and even used a length of steel pipe to shift some of the carbon shards towards the end. You can use pliers to pull out the long carbon shards and tip the rest of the debris out at the end.
    I realise this sounds drastic, but as has been mentioned above, the oxide that forms between tube and post grips the seat post so tightly that you’ll never shift it mechanically, unless you catch it in the early stages. Even separating the final shards requires quite a bit of effort (and care!). Of course you sacrifice the seat post in this way, but that is a good thing as you will be able to replace it with a lovely Thomson post, which won’t get stuck (if greased) and will probably be lighter than the carbon one anyway!
    I would suggest you do this job outside and/or use a mask, as the carbon dust is potentially nasty stuff to breathe in and just be patient and persevere and you’ll get there in the end, even though it may feel like mission impossible at times. It took me about an hour. A quick touch up of the inside of the seat tube with the correct size reamer will clear any tiny bits of adherent debris.

    simbob
    Member

    Thanks for all replies, comments & suggestions. Based on what everyone has said i think i will leave it alone for now (and suffer sore knees) we are only talking a need a raise it maybe 1cm – or purchase the same saddle as the original as an alternative. Hoping to replace the bike soon anyway.

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