Stuck seat post
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- Posts: 159
- Joined: 13 Jan 2008, 4:12am
Stuck seat post
I have a alloy seat post in a metal frame which refuses to budge. I’ve tried penetrating oil, ice and boiling water to no avail.
The seat post is in two sections and if you bash the saddle with a mallet the top of the seat post will move however the bottom of the seat post is still fixed. I’ve researched Sheldon Brown etc and would like to would like a specialist to sort this as I don’t want to damage the bike.
There’s a guy in Lancs who has specialised jigs and will do the job for £80 which I’d pay but I’m far away and don’t want the faff and expense of stripping the bike and sending the frame up there. Does anybody know of a specialist that offers such a service within 100 miles of Surbiton, SW London?
The seat post is in two sections and if you bash the saddle with a mallet the top of the seat post will move however the bottom of the seat post is still fixed. I’ve researched Sheldon Brown etc and would like to would like a specialist to sort this as I don’t want to damage the bike.
There’s a guy in Lancs who has specialised jigs and will do the job for £80 which I’d pay but I’m far away and don’t want the faff and expense of stripping the bike and sending the frame up there. Does anybody know of a specialist that offers such a service within 100 miles of Surbiton, SW London?
Re: Stuck seat post
Two thoughts.
Did you try heat on the frame before trying to remove it? Heat here meaning enough to dry out (and so shrink) the aluminium oxide around the seat post. Contracted oxide means less tight in the frame. Heat here means not paint strippingly hot.
Assuming you want to save the frame, but are not to fussed about the seat post. Sometimes the seat will post move if only you can grip it enough - which you often can't, If you drill an M6 side hole through the seat post and put a M6 bolt through it, the bolt will stop the post from slipping round when the seat post is in the vice, so you don't need a crushngly tight grip on the seat post. You do need a feel on how hard you can twist the frame (assuming seat post in a vice), if you twist too hard you shear the seat post off leaving you with a much harder job.
Google "caustic soda seatpost" - disolves the aluminium, doen't harm the steel.
I said 2 things, actually it is three!
Any decent bike shop should (usually) manage to get a seat post out, though often due to teh variability of the job, can't give a price until it is done.
Did you try heat on the frame before trying to remove it? Heat here meaning enough to dry out (and so shrink) the aluminium oxide around the seat post. Contracted oxide means less tight in the frame. Heat here means not paint strippingly hot.
Assuming you want to save the frame, but are not to fussed about the seat post. Sometimes the seat will post move if only you can grip it enough - which you often can't, If you drill an M6 side hole through the seat post and put a M6 bolt through it, the bolt will stop the post from slipping round when the seat post is in the vice, so you don't need a crushngly tight grip on the seat post. You do need a feel on how hard you can twist the frame (assuming seat post in a vice), if you twist too hard you shear the seat post off leaving you with a much harder job.
Google "caustic soda seatpost" - disolves the aluminium, doen't harm the steel.
I said 2 things, actually it is three!
Any decent bike shop should (usually) manage to get a seat post out, though often due to teh variability of the job, can't give a price until it is done.
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- Posts: 1923
- Joined: 10 Jan 2014, 8:39am
Re: Stuck seat post
You might find someone local with a jig on the Facebook group? https://www.facebook.com/groups/372288659621602
Has part of the post broken off inside? I don't know how you could extract that save for dissolving with caustic soda.
Has part of the post broken off inside? I don't know how you could extract that save for dissolving with caustic soda.
Re: Stuck seat post
Very worrying statement
I have a big vice attached to a big bench bolted to a wall. I’d be happy to help you but not if you don’t want to strip down to pretty much just the frame. PM me if you’re interested and NW Kent is close enough to you.
Re: Stuck seat post
You say ‘metal’ frame.
Do you mean steel, aluminium, titanium, magnesium....?
Is it welded, lugged, bonded..?
Do you mean steel, aluminium, titanium, magnesium....?
Is it welded, lugged, bonded..?
The older I get the more I’m inclined to act my shoe size, not my age.
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- Posts: 159
- Joined: 13 Jan 2008, 4:12am
Re: Stuck seat post
Thank you for your replies and links, lots of good information there.
PT 1029 I haven’t applied heat part from boiling water ( and ice ). I really need the use of jig/ massive jack.
peewee I said “metal frame “ doh should have written steel ( welded ).
Fausto 99 Thank you for your kind offer PM on way.
Thanks again all. What a helpful forum this is.
PT 1029 I haven’t applied heat part from boiling water ( and ice ). I really need the use of jig/ massive jack.
peewee I said “metal frame “ doh should have written steel ( welded ).
Fausto 99 Thank you for your kind offer PM on way.
Thanks again all. What a helpful forum this is.
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- Posts: 585
- Joined: 30 May 2020, 12:43am
Re: Stuck seat post
A proper release agent not WD 40 as water dispersant
Hacksaw handle and cut Almost right through and peen in the post without damaging frame
Slide hammer on post with m8 12.9
Impact gun socket and m8 12.9
https://youtu.be/P-YpmDx86d0
Hacksaw handle and cut Almost right through and peen in the post without damaging frame
Slide hammer on post with m8 12.9
Impact gun socket and m8 12.9
https://youtu.be/P-YpmDx86d0
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- Posts: 585
- Joined: 30 May 2020, 12:43am
Re: Stuck seat post
ClappedOut post_id=1594308 time=1617621893 user_id=51486]
A proper release agent not WD 40 as water dispersant
Hacksaw handle and cut Almost right through and peen in the post without damaging frame
Slide hammer on post with m8 12.9
Impact gun socket and 2 m8 12.9 and a cobalt drill bit better than one in video go slow with lube drilling impact socket
A proper release agent not WD 40 as water dispersant
Hacksaw handle and cut Almost right through and peen in the post without damaging frame
Slide hammer on post with m8 12.9
Impact gun socket and 2 m8 12.9 and a cobalt drill bit better than one in video go slow with lube drilling impact socket
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- Joined: 9 Jun 2008, 8:06pm
Re: Stuck seat post
Any chance of the last bit in English? It sounds good but something has gone wrong with the formatting, I think!
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- Location: Norfolk
Re: Stuck seat post
I'd only use the hacksaw method as THE VERY LAST RESORT! One slip and the tube is damaged! The caustic soda appears to be a much slower/better method.
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- Joined: 2 May 2016, 10:21am
Re: Stuck seat post
I've tried all the suggestions (except caustic) on my Reynolds 531 frame with a stuck Campagnolo aero seatpost ... with zero success. On a trip from Aberdeen to Southampton I dropped the bike off at https://theseatpostman.com and picked it up on the way home. I can't recommend him highly enough. He did a perfect job. He did warn that if you mess it up too much trying to get it out yourself (e.g. the hacksaw method) then it makes it more difficult (read expensive) for him. And if he finds you've cracked the frame, he won't touch it.
Note that using caustic is a) highly risky, b) highly messy, and c) ruins the paint job.
Phil
Note that using caustic is a) highly risky, b) highly messy, and c) ruins the paint job.
Phil
Re: Stuck seat post
a) Yesphilkeeble wrote: ↑6 Apr 2021, 1:01pm
Note that using caustic is a) highly risky, b) highly messy, and c) ruins the paint job.
Phil
b) Yes
c) Not necessarily. I had to do the same on a 753 Peugeot which was ‘in soak’ for two days and the paintwork wasn’t affected.
The older I get the more I’m inclined to act my shoe size, not my age.
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Re: Stuck seat post
I’ve tried ammonium hydroxide with success. Left it in overnight.
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- Joined: 30 May 2020, 12:43am
Re: Stuck seat post
A suitable impact socket cross drilled cobalt drill bit with M8 12.9 tensile strength bolts and nylock nuts.rogerzilla wrote: ↑5 Apr 2021, 4:21pm Any chance of the last bit in English? It sounds good but something has gone wrong with the formatting, I think!
The two bolts through socket and tube spread load. The hammers of impact gun more chance of breaking corrosion without tube collapse.