Carbon seat post stuck. How to remove it?

CiBCiB Posts: 6,098
edited April 2013 in Road beginners
Also posted in http://www.bikeradar.com/forum/viewtopic.php?t=12613865, but this forum seems to be a font of knowledge and advice.

The original saddle on my Scott S20 broke last year. I now have a decent saddle but it's added ¾" to the total height and I need to lower it. Problem is that the carbon post is jammed in the alloy frame. My LBS had a good try at extracting it when it was in recently for a few days but gave up. I'm happy to buy a new post in the expectation of destroying the old one in getting it out, but how best to do this without damaging the frame?

Thanks in advance...

Posts

  • HeadhuunterHeadhuunter Posts: 6,494
    Clamp it in a strong vice then try to twist the frame off the post, gently so not to damage the frame if poss?
    Do not write below this line. Office use only.
  • dennisndennisn Posts: 10,327
    You could cut it off a couple of inches above the frame with a hacksaw, then take the hacksaw blade itself and cut vertically through the post walls that are left. Being VERY careful not to cut into the frame.

    Dennis Noward
  • crankycrankcrankycrank Posts: 1,830
    Drip some penetrating oil around the top of the ST and let sit overnight. If it still doesn't come loose pour some boiling water over the ST and try again. The heat may cause the ST to expand just enough to break it free.
  • HeadhuunterHeadhuunter Posts: 6,494
    Begs the question - how did you get it in there in the 1st place? You're not supposed to hammer them in with a mallett like a tent peg you know :wink:
    Do not write below this line. Office use only.
  • doyler78doyler78 Posts: 1,951
    I had this problem a month or so ago. The only thing that worked for me was to heat the seat tube with a hairdryer and this expands the metal however it will take 2 people. One twisting and one pulling. If you have a fragile looking seat replace it with a cheapo one (probably the one you got with your bike :wink: ) as you will have to apply significant force and this could snap a less sturdy seat.

    Good luck.

    Once you do get it off get yourself some carbon paste. I ended up getting the scott carbon compound.
  • CiBCiB Posts: 6,098
    Thanks all for the tips. Hairdryer treatment followed by - if unsuccessful - judicious use of a hacksaw blade (which was Plan A initially) sounds favourite. Coke etc has failed in the past, for me and the LBS who had a go.
    Begs the question - how did you get it in there in the 1st place? You're not supposed to hammer them in with a mallett like a tent peg you know :wink:

    Aah - I thought it was a job trying to get it in. That would explain the oval wheels too then. :)
  • GuyGadoisGuyGadois Posts: 37
    dip the area in very cold water and then a bucket of very warm water. The cold will contract it and the warm water will expand it and crack that seal.

    -GG-
    Creator of ProLog Cycling 2011 (also 2010, 2009 & 2008) - Excel based cycling log for avid cyclists
    http://www.ProLogCycling.com
  • markwalkermarkwalker Posts: 953
    get down to halfords and get a can of "shock and unlock" thatll get the bad boy out. I even got a steel / alluminium weld apart.
    Rouler. Not Climber
  • CiBCiB Posts: 6,098
    Hrrmmph. Two hacksaw blades, one can of shock & unlock, a sprained shoulder and trip to the LBS to get the last 2" out, but it's out. Grrrrr.

    Turns out not to be a carbon post, but an ally one with a carbon wrap. What a swizz... The best clamp I found that didn't turn with the frame was the drain outside my house. Tip - a seat clamp fits nicley in the drain slot, and the drain doesn't turn. What does turn is the clamp in the rest of the post though. Bother.

    Resorted to hacksawing down the inside edges in two places, but still couldn't budge it. Eventually it did move and I was able to get it 3 parts out but it jammed and I couldn't get enough grunt to shift it any more. Trip to LBS - praise The Lord for Sunday opening [yes I know..], and three of us grunted it out eventually. Root cause - the carbon wrap had welded to the down tube. The seat post came out and left the wrap behind. Cue an armful of cleaning & tidying out of tubes back home.

    The new post is now in place. I reckon I'll be shifting it every weekend for the next 3 months just to prevent this performance again.

    Thanks for all the tips though.
  • dennisndennisn Posts: 10,327
    FWIW I have used a carbon post in a steel frame for quite some time a, never paid much attention to it other than an initial greasing, and never had a problem. Must be aluminum
    and carbon just don't like each other? Is that the case? C'mon all you material engineers
    out there. What's the deal?

    Dennis Noward
  • CiBCiB Posts: 6,098
    The new carbon post that I've put in the alloy frame went in with a coating of grease speficially for that combination. I suspect that it was oxidisation inside the frame that caused the problem though - I couldn't get he unmangled top end of the old post back in, not unitl I gave it all a throrough cleaning, then it fitted like a glove. The new one dropped in nicely too, with its smear of grease. The grease on both surfaces should do the job, but I'll still be checking it from time to time.
  • CyclingBantamCyclingBantam Posts: 1,299
    I have a Carbon Frame but an Alu seat post. Should I do anything special with this? I heard that you shouldn't put grease on Carbon as it can damage it? Is this the case and if so, how do I stop it sticking?

    Thanks

    Ben
  • dennisndennisn Posts: 10,327
    BenBlyth wrote:
    I have a Carbon Frame but an Alu seat post. Should I do anything special with this? I heard that you shouldn't put grease on Carbon as it can damage it? Is this the case and if so, how do I stop it sticking?

    Thanks

    Ben

    I had a carbon post in a steel bike for 4 years. Greased it up maybe 3 times using "just
    plain grease". Never had a problem. The only reason I'm still not using it is that my paranoia about it breaking got beyond an acceptable level. So I switched to a Thomson
    aluminum one.

    Dennis Noward
  • jairajjairaj Posts: 3,009
    You can get carbon assembly paste which is a special type of grease for carbon components to stop them bonding to stuff. you can use it on your seat post, stem, handlebars etc.
  • CiBCiB Posts: 6,098
    jairaj wrote:
    You can get carbon assembly paste which is a special type of grease for carbon components to stop them bonding to stuff. you can use it on your seat post, stem, handlebars etc.
    My new post came with a sachet of just that, which has been liberally smeared on both surfaces.
  • After having just removed my FSA carbon post from carbon frame with an alloy collar inset into the frame allowing to clamp the post, thought I would add my pennies worth on how I did it.

    First of all, bad language shouted loudly and vociferously at the inanimate piece of carbon, really does help the process.
    The post came out about an inch before coming jammed. Leverage/pull then became the main problem. Eventually I positioned the frame behind stair banisters, threaded the seat post through and re-attached the seat. This allowed me to pull against the frame while twisting the seat. Also worth noting, I tied the frame down to stop it damaging itself and I threaded a steel bar through the seat to give me extra leverage to twist. Was amazing how much twist force that post withstood, and didn't crack, buckle or anything. Eventually got to within about 7-8 cm to end of post and it became completely jammed. Bad language definitely needed here.
    Then got a hacksaw and cut off post flush with frame. Because I have the alloy insert took the chance and used a jigsaw to then cut a slot out of the seat post tube, a good jigsaw allows you to cut vertically down the post, pretty evenly top and bottom. I then used a screwdriver to 'flake' the cut section of post, which once it started to go, came out easily in layers, rest of the tube then pulled out easily by hand.
    Upon inspection, the alloy insert had some residue on it which I have now removed, and I've cut the carbon post down to a size that is suitable for me. Having read previous posts, I intend to inspect and remove the post a couple of times a year from now on.
    Would have been easier with an extra pair of hands to help, patience and breaks help. Didn't like the carbon dust when cutting it, very fine, scarf over mouth probably sensible.
    Good luck, a horrible job, but everything is possible.

    and yes, I'm still using the same seat post now.
  • CiBCiB Posts: 6,098
    Blimey - was that 4 years ago?

    I now routinely take the seat out every few weeks or so and give it a clean and another dose of carbon grease (different bike), partly because it does stick after a while if left to its own devices, and partly because the bunch of second-rate baboons at the national chain that I bought this bike off wriggled out of a warranty claim by finding a paragraph in the handbook that says the seat post must be cleaned monthly. I've no idea how failure to clean the post affected the internal clamping mechanism.
Sign In or Register to comment.