Aluminum Seatpost Stuck in Steel Frame:7 Easy Solutions

Aluminum seatposts might get stuck in steel frames for various reasons. But whatever the reason, the issue will be a real pain. 

So what to do when the aluminum seatpost stuck in steel frame

You must first determine why aluminum seatpost is stuck in steel frame. Now there are many ways to get it unstuck. The seat post can be dissolved using ammonia or gallium, it can be cut. You can also use thermal expansion and contraction. Preventive measures for the future should be taken. 

This just lists the different things you can accomplish. The article has more information! Just follow us!

Troubleshooting the Stuck Aluminum Seatpost in Steel Frame

Before you can start the removal process, you must first understand how it got stuck. There are usually two reasons why the seatpost might get stuck. Seatposts can get stuck in carbon frames too.  

Well, it’s a common phenomenon. Here’s someone who faced similar issue.

So, let’s troubleshoot the issue.

Stuck Aluminum Seatpost in Steel Frame
Source: Freaky Cyclist

Oversized Seated Forced Into The Frame:

When a large Seatpost is pressed into the frame. It frequently causes visible bulging in the seat tube.

Even if you can’t see it, you may occasionally feel it by sliding your hands down and up the seat tube towards where the seat post should terminate.

Thin-walled Seat Frame Unframed:

If a thin-walled Seatpost is distorted. As a result of tightening the Seatpost bolt too much. This is generally noticeable when the Seatpost comes out from the seat tube.

The Seatpost might not be spherical. In that case, you should not anticipate it to move upwards of a few inches from to the side. If you push it far radially, it may jam even more tightly.

Remove Aluminum Seatpost from Steel Frame

Now let’s get to the main part of pulling out the aluminum Seatpost from the steel frame.

Process 1: DIssolving Using Ammonia

Remove the seat binding bolt. The binder collar should be slid up the Seatpost. Allow ammonia to accumulate surrounding the Seatpost over nighttime.

Ammonia, like antifreeze or cola, dissolves aluminum oxide. Only a steel Seatpost in a steel frame would function with penetrating oil.

Loosen the bottom bracket and spin the bike upside down for optimal penetration. Then, pour in ammonia, anti-freeze, or cola from the steerer tube’s base and let it overnight.

Process 2: Using Thermal Expansion and Contraction

Thermal expansion and contraction are possible. The aim is for the Seat post or the seat tube to contract and separate from the seat tube. Either the seat tube will expand or slide away from the seatpost.

Cool the aluminum Seatpost that is imprisoned within a steel frame. After removing the crankset, there should be a large enough hole. It will go from the bottom bracket shell all the way to the seat tube.

Drop in little pieces of ice cubes and allow the posts to become very chilly. Release the whole cartridge of a CO2 tire inflator from the Seatpost junction. It will both freeze and shrink as a result of the seat belt.

Using Thermal Expansion and Contraction
Source: iFixit

Process 3: Using a Clamp

The rest of the processes are a bit challenging. Lock the tip of the Seatpost into a huge bench vise that is securely fastened to a sturdy working bench. 

Remove the saddle as well as any clamps from the forward base of the Seatpost. Turn the bike around and set it over the vise.

You just smashed your Seatpost. Never, ever ride it again.

Rep the thermal expansion/contraction procedure from the previous stage.

Take hold of the framework at both ends and carefully twist it. Be aware that exerting substantial force may cause your frame to break or fracture.

When the Seatpost finally fails, it usually produces such a loud “pop” that you think you’ve broken everything!

Process 4: Cutting Off the Seat Post

Just above the seat lug, remove the Seatpost. You currently have various options accessible to you.

Warm it up using a hair dryer to enlarge the seat-lug space. For freezing and shrinking the Seatpost, insert the entire cartridge of a CO2 tire inflator into it. Clamp what’s left in a vice and attempt to twist it.

Purchase a sliding hammer. Connect the rod tip to your Seatpost and secure it using vise-grip pliers.

A transversal shaft can also be drilled through it. Install the slider onto the shaft of the slider hammer and secure it with a pair of clamping pliers. Hooks pointing inward toward one another can also be inserted into the holes.

Have someone hold the frame as you pound the weight away from it. It will almost likely pop open.

A half-inch hole can be drilled transversely through the Seatpost. Thread a long steel rod through the frame while someone holds it. then twist it as tightly as you possibly can. It will make a lot of noise once it is out.

If the Seatpost is still not fully out, you will have to put in some effort. You can take it to a mechanic. 

You should naturally assume this before proceeding with caution. Because you risk completely damaging your frame.

Remove your Seatpost approximately an inch above the seat lug on your bike frame. Detach the blades from the saw with a hacksaw. Wrap a strip of tapes over one end to create a grip with which to hold it.

Secure the glued end and put the other side into the center of the post. Cut two outward circular cuts 60 degrees apart. The goal is to extract a wedge out of the Seatpost hunk that’s trapped in your frame.

Complete the last component. When you have completed your cut, pry or pull the part out with a large screwdriver or a pair of pliers.

Be cautious here as well. By prying too hard here, some amateur mechanics have destroyed their frames.

Cutting Off the Seat Post
Source: Cycle About Town

Process 6: Dissolving Using Gallium

So can you dissolve aluminum seat posts? 

Gallium can dissolve aluminum. It will not, however, affect the metal frame. And you should get some of the material the frame is made of. And first, test the frame with some liquid metal. Remove and grease your Seatpost now that it is free of the frame. 

Do it once in a while. Remove any excess water from the frame while you are at it.

Process 7: Going to a Workshop

Now some of the solutions we mentioned might be a little too difficult for home mechanics. And they run the risk of permanently damaging the bike. So it may be helpful to resolve the issue with the help of a mechanic. 

Request Seatpost removal service. The specialist will use an air impact hammer to crush the bottom of the Seatpost clamp. If it works, it will require a few minutes and will not damage the frame. However, be warned that it is really loud and violent.

You may have already cut out the Seatpost partially. If that is the case, you can take the help of a mechanic to do the remaining removal. 

You may take the remaining Seatpost to a machining shop. They can smack down out of the seat tube. However, the odds of the retailer properly aligning everything are slim. As a result, the cutter may not make a cut in the seat tube.

Preventing Seatposts from Getting Stuck In the Future

We thoroughly discussed stuck Seatpost removal tools and techniques. But preventing the Seatpost from getting stuck is truly the best solution. Now below are some steps you may take to avoid this in the future.

Using Grease:

Use grease at all times. Before installing the seat post, coat the interior of the seat tube with oil all the way around. 

It is not necessary to oil the Seatpost if adequate grease is used in the seat tube.

Never Use a Hammer:

Do not use a hammer to attach a Seatpost.

Install a basic “pipe-type” Seatpost without a saddle. They can fall too far and become lodged in corners that one can’t reach easily.

For Telescoping Seatpost:

With a telescopic or articulated suspension Seatpost, prevention is even more crucial. Attempting to spin it aggressively from over the gear will easily harm it. Here are some of the best seatpost you can buy.

  • One of the best seatpost is UPANBIKE Bike Seat Post Aluminum. You can check the price
  • For avoiding rust, go for ONIPAX Forged Aluminum Seatpost. You can check latest price
  • If you want to enjoy off-roading, then go for GANOPPER Suspension Seatpost. You can check the price
JPM Group
Source: JPM Group

Frequently Asked Questions (FAQs)

Why is my dropper post stuck?

It might be stuck due to too much stress on the cable. If your dropper post moves without you pulling the lever (it won’t remain up while riding), the cable is too tight. You’ll want to remove the tension. Rotate the barrel’s adjustment forward to do so.

Does caustic soda dissolve Aluminum?

Caustic liquids dissolve aluminum. Try a hot sodium chloride concoction at a concentration of 40 g/l. If this does not work, give it more strength. However, keep an eye out for each glass. 

Can you heat aluminum to get a bolt out?

Yes, you can heat metal to extract a bolt. To dissolve this connection, heat must be used to expand the metal. Because aluminum is a great heat sink, it takes a lot of energy to liberate the rusted bolt.


With that we know so much more about aluminum seatpost stuck in steel frames. First, figure out how the problem happened. And then there are multiple ways to solve the problem. 

Good luck!

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top