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HOW TO ~ Unstick a Stuck Seatpost

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We ride Fatbikes in all sorts of nasty conditions. You might be up to the toptube in swamp water or maybe riding across salty, sandy beaches or even just salt covered slushy roads and bike-paths. Whatever it is our Fatbikes take a lot of abuse and even though you might take care to wash your bike and lube your chain on a regular basis there is one component that if its doing its job properly does not get much notice, the Seatpost. Sure, it’s there to hold your seat in one place and not move at all but one day you might want to lower your seat to let someone else throw a leg over your trusty steed. So you loosen the seatpost binder bolt and….nothing… no amount of swearing or wrenching on the seat can budge it.

Uh-Oh your seatpost is seized, now what? Well that depends, how seized is it? First thing to try is just riding it around with the seatpost binder bolt loose. If its not terribly stuck a few curbs and bumps can get it moving again. But no one is that lucky. Usually when it’s stuck it’s really stuck, like so stuck you could hang an elephant from the BB and feel pretty secure standing under it.

So now what? Well most peoples first instinct is to somehow twist it out either by putting the seatpost in a vice or clamping a Vice-Grips on it and twisting with a cheater bar (AKA a big ass pipe) this is a bad idea. Frames aren’t built to take a twisting load like that and you can trash your frame or put it seriously out of alignment by doing either one of those things.

In the end you have a few options:

  1. The coke method – pour something corrosive down your seattube and let it eat away the galvanic corrosion (usually the reason your seatpost is stuck in the first place)
  2. The hot / cold method – heat your seattube up so that it slightly expands and allows the seatpost a bit of wiggle room. Or conversely’ cool the seatpost down so it shrinks a bit. Ive never seen much success with this and it usually involves destroying your paintjob or getting ahold of dry ice so I’m not going to talk about this method.
  3. Seatpost destruction method – sawing your seatpost in half vertically. the least fun and most frustrating but the only method guaranteed to work.

Let’s start out with the Coke Method

First, a list of supplies.

  1. Bottom Bracket removal tools
  2. A can of Coke
  3. A baggie and rubberband or some other way to seal your seatpost

First things first. You need to pull your Bottom Bracket, this will allow you access to the seat tube from the bottom bracket shell. After you have pulled your BB flip the bike over so the seatpost is facing the ground, a workstand helps here but is not essential. Then, use a ziplock bag and rubberband to seal the opening in the top of your seatpost (assuming there is one). Once you have it all sealed up pour the Coke slowly into the bottom bracket area and let it run down the seat tube. I taped off the holes that ran to the chainstays and downtube but I don’t know how important that is.

Once you have the seattube full of Coke let it sit overnight checking on it occasionally to make sure that the coke hasn’t all leaked out. I let mine sit for something like 3 days.

letting it sit

After letting it sit, drain the Coke and see if you can move the seatpost, supposedly it should be pretty easy to unstick by tapping on the seatpost with a rubber mallet or something of the sort. In my case nothing happened, so I include this method in hopes that it actually will work for someone. (let me know in the comments if you have had it work)

If that failed well you have a pretty easy math problem.

$80 Seatpost < $600 Frame

Assuming your seatpost is not made of Platinum its a pretty easy decision to make, sacrifice the seatpost.

For this operation you need:

  1. A hacksaw
  2. A couple hacksaw Blades
  3. A drill
  4. A slide hammer or something improvised to work like a slide hammer
  5. A vice grips
  6. A bit of strong metal wire (coat hanger or, even better, a spoke)

Start by cutting the seatpost off leaving about an inch exposed above the seattube. Yes I know taking a hacksaw to an expensive seatpost is really hard to do but sometimes extreme measures are called for.

Next, take a hacksaw blade and wrap some tape or an old tube around part of it to make a handle (it will make this procedure suck slightly less)

hacksaw

Then slide the blade down the seattube and press in on the wall of the seapost and pull up (make sure the teeth of the blade are facing up towards you so it cuts on the upstroke) keep the blade as parallel as you can so it cuts evenly.

Eventually you will have a cut like this, when I say eventually I mean it. It will feel like eternity but really it will take 15-20 min of sawing very slowly and carefully.

sawing

Make sure you only go through the seatpost and not the seattube, in practice this won’t be hard since you will be going so slowly.
Once you have cut all the way through grab your vice grips and crush that seapost. At this point it will be very satisfying to destroy it since your knuckles will be bloody and your hand will be sore as hell. If all goes well you should be able to close that gap you just made in the seatpost.

It may be that that is enough to free the seatpost and you will be able to twist it out right there. If so, awesome! if not, drill a hole in the seatpost and thread a spoke through it and make a loop and attach something heavy to it. Like a slide hammer, or in my case a 2×4 screwed to a vice grips and a regular hammer to hit that with. Then flip it over again and bang on it a bit, if all goes well it will pop out like so.

post out

You may need to make additional cuts if you can’t get it to move. (I’ve heard of people having to make 4 cuts ~shudder~)

In the end though it will come loose. I promise. In the picture above you can see all the galvanic corrosion that caused the problem in the first place.

Lastly, we want to make sure this NEVER EVER EVER happens again. So, find a hone, or in my case since they are apparently unavailable in all of San Diego, get a drill bit extension and a wire wheel. Pop that in your drill and get all the built up rust and corrosion out of that seat tube.

After that get a new seatpost and GREASE THE HELL OUT OF IT!!

It’s always good to pull your seatpost after a very wet ride since it not only makes sure your seatpost won’t get stuck it allows the water in the frame a place to evaporate out of and will extend the life of your frame.

Hopefully, you never need this article but I assure you it will come in very handy the day you go to move your seatpost and nothing happens.

7 Responses to HOW TO ~ Unstick a Stuck Seatpost

  1. Tony B. January 25, 2012 at 8:21 am #

    GREAT information. I think I’ll grease the crap out of my seat post tonight if I can get it off.

    Thanks for the great write up! I love Fat-Bike.com

  2. Sean January 25, 2012 at 8:51 am #

    I had this happen with my first MTB, a steel GT Karakoram with an aluminum post. I had ridden the bike periodically in winter and experienced galvanic corrosion for the first time. Yuck!

    In my case the post had about 8-10 inches exposed from the frame. We cut the head off to allow a 10lb York barbell plate to fit on it and then screwed a massive steel cap head machine screw with two big flat washers into what remained of the top of the post. We took the BB out, inverted the frame and soaked the insides of the seattube with a penetrating oil, letting it sit overnight to soak in.

    The next day we pounded up and down with the barbell plate like a slide hammer, sliding it up the seatpost and crashing back down on the spacers and bolt head until it eventually worked its way out of the frame. It took quite a while, maybe an hour or more. Once out, I honed that bugger but good! No frame or paint damage, just a pooched post.

    Learned my lesson though. I take my seatpost out regularly, clean it and grease it liberally.

    Ah, the lessons learned through cycling and the dark arts of bicycle mechanics…

  3. Bosco January 29, 2012 at 3:13 pm #

    Over the years I have had incredible results using PB Blaster on anything stuck, corroded or rusted.

  4. Tony B. February 3, 2012 at 9:49 am #

    WOW went to put my new seat on last night and my post BARELY came out. I’ve reinstalled with plenty of lube and will be checking it often. Great timely advice from Fat-Bike!

    Check those posts guys/gals.

  5. Patrick P June 4, 2012 at 2:30 am #

    Working on removing the seatpost from a vintage ten-speed circa 1976. Have been adding liqid wrench to it daily for past week with no effect. Next I will try removing the bottom bracket to administer penetrating oil from below. Maybe I can get some PB Blaster for the job.

  6. Thomas September 15, 2013 at 4:28 pm #

    i had a stuck seatpost on my mountain bike. tried WD40 (it was what i had), and pretty much hanging the bike from the seat, nothing. i took off the seat and was able to pound on the top of the post with a hammer to at least get it unstuck, then a pipe wrench (set on the top bracket of the seat post that holds the seat, so as to not wreck the post pipe) helped me twist it out.
    it was completely covered in rust inside, so i used a wire brush to get as much as i could out, and then covered the inside with grease.

  7. Wolverine5 May 10, 2014 at 7:45 pm #

    I probably will have to use the hacksaw way because i’v tried everything else. It’s an aluminium seat post with a steel frame…

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