Hacksawing a stuck seat-post - yes or no?

[Combat_Butler]

I just bought an old but rather nice Dawes Omega MTB for £55, it's in good condition BUT the seat-post is stuck... very, very stuck.

It's a lightweight steel framed bike and I think - just to make things interesting - the seat post is aluminum and has been hammered into the frame by a gorilla with a sledgehammer so removing it is going to be a challenge. How long would it take to saw down the length of the seat post? Should I leave well enough alone or give it a go?

 

[Beau]

Before you get all Jim Duggan on that thing try a few things first.

Over time aluminum and steel will fuse themselves together if not lubed. Pull the water bottle cage bolts out of the seat tube and spray penetrating fluid into the frame with the bike upside down.

Let it sit a couple days.

Then pull the seat and wheels off. Find the biggest bench vise you can and clamp the seatpost (the whole .... bike upside down) into the vise. Use the frame as the leverage to try and rotate the seatpost out of the frame.

I have had to get two people to help me with some posts. one to rotate the frame and two other to pull up on the frame.

It's pretty rare that you have to cut the post out the long way, but if the vise doesn't break it loose, it will probably ruin the post anyway.

Break out the sweat band!

 

[Beau]

oops. looks like the frame doesnt have bottle cage braze on's. You can also pull the cranks and BB and spray fluid through the BB shell, down into the seat tube.

 

[deorman]

I can't stand stuck stems or seat posts myself, even if they're adjusted right. I guess it depends on how far down it goes. Aluminum cuts pretty easy, will your blade reach?

 

[Combat_Butler]

oops. looks like the frame doesnt have bottle cage braze on's. You can also pull the cranks and BB and spray fluid through the BB shell, down into the seat tube.

That is nevertheless a cunning trick! I've never removed a bottom bracket or cranks before but I think it's time I invested in a couple of new tools, I wouldn't mind giving it a try. Thanks Beau.

 

[X-RAY]

ever consider adding a bottle cage to the seatpost? drill the hole, spray in pbblaster, later on put a rivnut in the hole so nobody know. 8)

 

[Tailwinds]

Sadly, I've had the same problem with an old Schwinn road bike. Same scenario, steel frame, alum. seatpost, fused.
I tried penetrating oil. I soaked the frame in ammonia for days(a common recommendation for such problems). Tried all the tricks.
Eventually I was resigned to sawing the seatpost lengthwise. IT WORKED! And, although it certainly took a couple of hours (I took a break here and there), it really wasn't such a terrible exercise.

 

[Beau]

We charge $60 an hour to remove them. Some customers really get upset too.

I was going to mention the rivnut idea, but most people don't know they even exist. It's one of the best tools for bikes, hot rods and motorcycles.

 

[The LT]

Also if the seatpost is aluminum try to lube up the interface between the seatpost and the frame with penetrating oil and then freeze the whole thing. Aluminum has a much larger coefficient of thermal expansion than steel so you are going to have better luck if you can get it cold.

 

[kev]

I have been able to remove a couple stuck posts by first hammering them further into the tube. I usually clamp a vise grip onto the post about an inch above the tube and give the top of the post a few whacks with a hammer. once it starts going in i use the vise grip for leverage and twist it out.

 

[Lonewolf]

You can get it out in a few minutes with the vise grip trick.

Grab it with some good quality vise grips -hard.
Turn the frame upside down and you can probably get it out by hitting the vise grips directly with a hammer, close to where it is grabbing the post.

I just had to do this a few days ago. It took about a minute.

Violence is a great substitute for lubrication.

 

[Beau]

I wish they all came out in a few minutes.

 

[kngtmat]

I had the same problem too on my bike but I didn't use spray but I used all in one with the clear plastic tube inside then pulled it out then down let the oil down the tube from the bottom bracket then let it soak over night with the bike & a paper towel upside down, and the next day used the seat clamped tight and side to side then it came out.