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Don't know what you put in that message? Filter at work won't let me open it :shock:
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Stuck Seatpost Vs Slide Hammer
- Thread starter weeman_mtb
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Re:
When I got the seatpost out of my old Schwinn, I did it by flipping the frame upside down, and clamping the bottom bracket shell to the steel support beam in the garage. This left the seat tube was nearly vertical, with the slide hammer working downwards (with gravity to assist).
It did rattle the whole house, so you might want to do this when no one else is around! :?
When I got the seatpost out of my old Schwinn, I did it by flipping the frame upside down, and clamping the bottom bracket shell to the steel support beam in the garage. This left the seat tube was nearly vertical, with the slide hammer working downwards (with gravity to assist).
It did rattle the whole house, so you might want to do this when no one else is around! :?
Re:
Given the main issue is generally breaking the bond, why is this better than hitting it with a mallet or something?
I'm no engineer so feel free to pile in if that's a stupid question!
Obviously once the bond is broken I can see this would help but usually by then it's not too hard to get the post out
Given the main issue is generally breaking the bond, why is this better than hitting it with a mallet or something?
I'm no engineer so feel free to pile in if that's a stupid question!
Obviously once the bond is broken I can see this would help but usually by then it's not too hard to get the post out
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Its not a bond as such, more of an expansion
Bashing with 'ammer just moves that expansion further down the tube
Slide 'ammer whollops it out slooooooowly
Bashing with 'ammer just moves that expansion further down the tube
Slide 'ammer whollops it out slooooooowly
There's a few other reasons, too.
Twatting the top of a seatpost with a hammer will mushroom / bend / generally knacker it. That's not a problem as such, by the time you've got to that point it's considered effectively dead anyway, but the energy you're expending buggering it up beyond all recognition is energy that's not going into breaking the bond. And as it bends and mushrooms, more and more energy will be sapped by the beyond-plastic deformation you're doing to it. A slide hammer puts almost all of the energy at the place you want it.
Next up, you risk damaging the bit you really care about, the bike itself. Not just from slipping and putting a big ugly ding in the crossbar, but from the fact you're applying compressive forces to the seat tube. It's hard to bend a tube by pulling along it lengthwise. Much harder than pushing on it lengthwise.
Also, any sideways component to the hammer blow, and there will always be one unless you are a robot, will concentrate at the stress point at the bottom of the seat post. Unless you're clamping the frame higher than that, which is stupid. Sideways forces applied by a slide hammer will merely tend to make the entire frame / seatpost assembly align with the slide hammer itself; as long as you haven't anchored the bottom bracket in a vice, you're OK. Both risk breaking the bottom bracket, though.
A slide hammer is a controlled application of percussive pulling force to exactly the place, and, in this case, in exactly the direction, you want it. A hammer is - well, not very much that.
It's no magic bullet, though. Sometimes they just won't come out.
Twatting the top of a seatpost with a hammer will mushroom / bend / generally knacker it. That's not a problem as such, by the time you've got to that point it's considered effectively dead anyway, but the energy you're expending buggering it up beyond all recognition is energy that's not going into breaking the bond. And as it bends and mushrooms, more and more energy will be sapped by the beyond-plastic deformation you're doing to it. A slide hammer puts almost all of the energy at the place you want it.
Next up, you risk damaging the bit you really care about, the bike itself. Not just from slipping and putting a big ugly ding in the crossbar, but from the fact you're applying compressive forces to the seat tube. It's hard to bend a tube by pulling along it lengthwise. Much harder than pushing on it lengthwise.
Also, any sideways component to the hammer blow, and there will always be one unless you are a robot, will concentrate at the stress point at the bottom of the seat post. Unless you're clamping the frame higher than that, which is stupid. Sideways forces applied by a slide hammer will merely tend to make the entire frame / seatpost assembly align with the slide hammer itself; as long as you haven't anchored the bottom bracket in a vice, you're OK. Both risk breaking the bottom bracket, though.
A slide hammer is a controlled application of percussive pulling force to exactly the place, and, in this case, in exactly the direction, you want it. A hammer is - well, not very much that.
It's no magic bullet, though. Sometimes they just won't come out.
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Don't I know it.
weeman_mtb
Retrobike Rider
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Re:
When this "weeman sized" Kona Hahanna frameset came up locally last week I just had to have a little bid. Stuck bottom bracket and a stuck seatpost, perfect to keep the price low.
Bottom bracket was easy, despite the punch marks from a previous attempt, I just bolted the tool in place and used the vice. The broken plastic cup was easily smashed out afterwards. The seatpost was already cut off and had some evidence of hammer blows in the downwards direction. Method was the same as the Parkpre frame so I'll save the details, this one was an absolute pig to get out, I nearly gave up, ended up swapping to my heaviest attachment to get it going. About 7 1/2 inches of stuckness this time!
When this "weeman sized" Kona Hahanna frameset came up locally last week I just had to have a little bid. Stuck bottom bracket and a stuck seatpost, perfect to keep the price low.
Bottom bracket was easy, despite the punch marks from a previous attempt, I just bolted the tool in place and used the vice. The broken plastic cup was easily smashed out afterwards. The seatpost was already cut off and had some evidence of hammer blows in the downwards direction. Method was the same as the Parkpre frame so I'll save the details, this one was an absolute pig to get out, I nearly gave up, ended up swapping to my heaviest attachment to get it going. About 7 1/2 inches of stuckness this time!
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fearfactoryüberalles
Senior Retro Guru
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Whilst I admire the dedication which had been put towards this issue in the thread, I can't help thinking my method (copied from this site, of course) is far less easier/cheaper :twisted: .
It works only when there's seatpost outside of the frame, mind.
I clamp the seatpost in the vice, put some sponge material around the seattube to cover it properly (zip tie is the best to make it stay). Then I start to go mad with the freezing spray, giving to it around the seatpost area and from the BB shell (using some long straw-like plastic tube extension on the nozzle), wetting the sponge as much as possible and spraying the inside of the stuck seatpost. Then comes the brute force part: breaking the bond by twisting the frame sideways. Worked for me every time so far, though it can be a great workout in more stubborn cases :facepalm: .
It works only when there's seatpost outside of the frame, mind.
I clamp the seatpost in the vice, put some sponge material around the seattube to cover it properly (zip tie is the best to make it stay). Then I start to go mad with the freezing spray, giving to it around the seatpost area and from the BB shell (using some long straw-like plastic tube extension on the nozzle), wetting the sponge as much as possible and spraying the inside of the stuck seatpost. Then comes the brute force part: breaking the bond by twisting the frame sideways. Worked for me every time so far, though it can be a great workout in more stubborn cases :facepalm:
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enc
Kona Fan
Just spent hour n half getting the post from a cheap lava dome i picked up (cheap cause of the known stuck seat post)
1/ soak in WD40 / plus gas for a couple of days ... not budging.
2/ take to brothers place to try slide hammer.
3/ slide hammer bolted to Seatpost clamp with chain and post liberally doused in penetrating fluid the typle, i cant remember the name but he said it was a good one. tried like this for quite a while..minimal effect.
4/ keep the penetrating spray flowing ...
5/ huge set of Stilson's on the post and eventually, we got it to move from side to side
6/ brother applied sideways pressure with the stiltsons whilst I twatted the seat clamp at the top of the post with a huge copper faced hammer...hit upwards while brother twisted with stiltsons. at last we started to see movement ...about 10 mm in 10 minutes..then the inevitable happened.. the seat clamp pinged off.. to be fair it had taken (literally) a fair bit of hammer
7/ brother said he had some freeze spray but hadn't had much success with it saying its about as cold as water from a tap ... to demonstrate this he sprayed some on his hand ... not exactly liquid nitrogen cold then :roll:
8/ we doused the frame and post in this stuff and clamped the seat post in a vice ... two minutes later it was out :shock:
not entirely sure what moved the post, prov=bably a combination of all above... i know one thing for sure, id never knowingly buy a frame with a stuck post again :|
1/ soak in WD40 / plus gas for a couple of days ... not budging.
2/ take to brothers place to try slide hammer.
3/ slide hammer bolted to Seatpost clamp with chain and post liberally doused in penetrating fluid the typle, i cant remember the name but he said it was a good one. tried like this for quite a while..minimal effect.
4/ keep the penetrating spray flowing ...
5/ huge set of Stilson's on the post and eventually, we got it to move from side to side
6/ brother applied sideways pressure with the stiltsons whilst I twatted the seat clamp at the top of the post with a huge copper faced hammer...hit upwards while brother twisted with stiltsons. at last we started to see movement ...about 10 mm in 10 minutes..then the inevitable happened.. the seat clamp pinged off.. to be fair it had taken (literally) a fair bit of hammer
7/ brother said he had some freeze spray but hadn't had much success with it saying its about as cold as water from a tap ... to demonstrate this he sprayed some on his hand ... not exactly liquid nitrogen cold then :roll:
8/ we doused the frame and post in this stuff and clamped the seat post in a vice ... two minutes later it was out :shock:
not entirely sure what moved the post, prov=bably a combination of all above... i know one thing for sure, id never knowingly buy a frame with a stuck post again :|
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My favourite was is if the seat is still on the post, lay the frame down on the grass, shout loudly 'Look! Its Enrico Pallazzo!' whilst point in the opposite direction. I then jump on the saddle.
Sometimes, theres a loud crack.
Sometimes its the seatpost
Sometimes its the seat clamp
Sometimes its a case of getting a spade and digging the frame out of the ground.
But mostly it works 100%, 60% of the time.
Sometimes, theres a loud crack.
Sometimes its the seatpost
Sometimes its the seat clamp
Sometimes its a case of getting a spade and digging the frame out of the ground.
But mostly it works 100%, 60% of the time.
