Stuck seatpost, what next?
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_274625_langId_-1_categoryId_165594Posted 4 years ago
Get it cold.The difference in contraction between steel/ali might be enough to get you started.tonyplymMember
Worth trying some proper penetrating fluid (Plusgas or similar) rather than WD40; also worth applying some gentle heat (wrap a towel around the seat tube and pour on a kettle of boiling water; wait a minute or so and then try a twist – remembering that the frame/post will be hot).
In the past I’ve resorted to applying an air chisel (or drill set to hammer only) to the underside of the seatpost’s top clamp – the repeated high frequency hammering action worked to remove a well-stuck seat post for me.Posted 4 years agomaujaMember
I had a similar problem but an aluminium post in a carbon frame, in the end I took it to Argos Cycles in Bristol and they got it out with no damage to the frame or post for something like £15. Not sure how they did it but it took them no time at all and saved me a lot of trouble trying to do it myself.Posted 4 years agoel_bandidoMember
Ok, so my seatpost has become stuck. Aluminium seatpost, steel frame. I’m fairly surprised, as the bike has been stored inside, I last changed the saddle height about a month ago and the post had been previously greased.
Either way it’s definitely stuck now! So far I’ve tried completely removing the seat collar, spraying a load of oil and WD40 at the top of the seat tube. I’ve tried twisting with as much force as I can manage and taking the saddle off and tapping it downwards with a hammer. Doesn’t seem to be going anywhere
I’ve read all the stuff on the Sheldon Brown site and all over various forums but wondering what the most successful techniques have been for people on here. Feels like there should be a few other things I can try before I start messing about with amonia.
Any advice would be much appreciated!Posted 4 years agokayak23Subscriber
I am literally just in the process of this exact same problem. I bought an eBay bargain DMR frame, . Only the kid forgot to mention the severely stuck seatpost.
I tried all the brute force approach techniques, I also tried using ammonia left for several days and then more brute force and all I managed to do was break the bond off the clamp into the post…
What you need is caustic soda! Ghetto chemistry of the best kind!
You need to wear lots of safety gear, plug any frame holes so the solution doesn’t just pour away, and then start letting it do its thing. It’s taken me 3 bottles of caustic soda and a few evenings sitting there feeding the frame with it and avoiding the caustic volcano that erupts from the seat tube but it’s finally worked, eating the whole entire post right back to the steel…
Check out this blokes video for inspiration.
One thing I’d add is, don’t put a lid on the bottle you mix the caustic soda in as the gases can build up fast and be explosive… I used a Pyrex jar. It gets HOT quickly…Posted 4 years agotjg04Member
Although normally a lurker, after seeing kayak23’s post…
Most definitely DO NOT use caustic soda / lye / sodium hyrdroxide / Drain cleaner / Mr Muscle etc. Whilst you are correct in assuming the aluminimium will be dissolved you’ve also just created the perfect conditions for caustic cracking of the steel frame. Even if you left the frame untouched, the residual sodium hydroxide will do a great job of converting any grease it touches into soap. I cannot believe this information is on Sheldon Brown.
I’m all for ghetto chemistry, but if you do anything like this again. Always add the Acid or Alkali to the water, not the other way round. The gases you are talking about building up is the water boiling. Use a glass container (as you did but not the guy in the video), don’t cover and don’t shake. It will dissolve of its own accord. Also anything over 40g per litre of caustic soda is just overkill.Posted 4 years agobarrykellettMember
Used the caustic soda route with great success, had no problems with the frame afterwards.Posted 4 years agokayak23Subscriber
Always add the Acid or Alkali to the water, not the other way round.
Indeed. This is what I did and what it tells you on the packet.
The guy in the video clearly had a lax attitude to it and ended up shaking it and adding the top. He was lucky he got away with that. 😯
I think this is defo last resort territory, but it works…Posted 4 years agoZaskar93Subscriber
I had the same thing only I had a Thomson alloy post stuck in my Heckler alloy frame but I GOT IT OUT!!
Undamaged, apart from a couple of scuffs but perfectly useable too.
I had been spraying WD40 down the inverted frame for days and then with the seat off and bike still upside down I plugged the the seatpost and then filled it and the whole of the seat tube from the BB shell (BB removed!) with diesel and left it to soak. Stuck it in the bench vice a couple of days later 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 came 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. Oh, and moved and removed it every once in a while.
Best of luck.Posted 4 years agofatsimon mk2Member
cut top off post leaving at least 1.5″ showing using a hacksaw blade out of saw frame i.e blade on its own cut a slot down the length of post then cut another slot at 90 deg slot have to go through post or nearly through then use a punch or stout piece of wood knock piece inbetween slots out now squash remaining post together into slot post should now come out, slow and steady is the name of the game when doing this 🙂Posted 4 years agoraisinhatMember
Seatpost in a vice and twist the frame (but you can bend the frame if you push too hard!!)
Have done this with great success to an old clockwork frame, but in that case the post was steel as well, and the two had rusted together. The frame was fine, but the post was ruined. It took a lot of force to get them apart, and once they were the seattube was hot enough to burn my fingers when I touched it (couldn’t resist).Posted 4 years ago
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