stuck seat post

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crimble
Posts: 107
Joined: 29 Jan 2007, 8:49pm

stuck seat post

Postby crimble » 26 Nov 2010, 4:56pm

I have an extremely stuck seat post and was wondering what approaches to take with this [steel frame alloy post]. Any suggestions?

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anniesboy
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Joined: 16 Feb 2007, 10:16pm
Location: South Oxon

Re: stuck seat post

Postby anniesboy » 26 Nov 2010, 5:28pm

Have a look here ,in too good to lose

http://tinyurl.com/37p4n4y

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Greybeard
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Joined: 1 Oct 2008, 6:48pm
Location: East Yorkshire

Re: stuck seat post

Postby Greybeard » 26 Nov 2010, 8:00pm

I had this very problem when I decided to rescue an old GT Palomar frame. I posted details somewhere (along with pics of the dregs) in the depths of the togglechain tour bikes post :?
Image
Brute force and a well mounted vice meant I was able to snap the top of the post off - you may be lucky and find that it even frees it :P I wouldn't bother with any heat as the alloy will expand faster than the steel, which won't help :wink:
Pack the bottom bracket area with plenty of rags to seal it up and carefully pour in strong caustic soda solution. It bubbles and squeaks and spits so be extremely careful :shock: - it also gets very hot. Using that and a very thin, long, sharp chisel over the course of 4+ hours I did get it out. It remained very stubborn right to the last bit.
Not exactly a clean and totally safe method - so if you decide to have a go, it's at your own risk :roll:

Steve

cycloret
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Joined: 17 Jun 2010, 9:48pm

Re: stuck seat post

Postby cycloret » 27 Nov 2010, 12:39am

Assuming you get the seatpost unstuck and the new one is also tight, consider getting your LBS to ream the seat tube. I bought a reamer and have already used it on two of my frames. They seem to have gone up in price since I bought mine two years ago.

http://www.framebuilding.com/economy%20 ... ilding.htm

crimble
Posts: 107
Joined: 29 Jan 2007, 8:49pm

Re: stuck seat post

Postby crimble » 27 Nov 2010, 2:36pm

thanks and thanks for the other page ref. I might try the ammonia route with Brasso as it has ammonia in it

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martin biggs
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Location: northamptonshire
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Re: stuck seat post

Postby martin biggs » 27 Nov 2010, 3:09pm

i had a steel post stuck in a steel frame till 3 nights ago , the way i did it was a copious soak with stale coca cola left for a couple of nights then removed saddle from clamp and inserted 2 long still metal rods into the seat rail clamps and did the clamp bolt around the stem up really tight and a good squirt of Plus gas and just started trying to move them stem slightly with no joy so wedged a thick bladed screwdriver into the seat bolt clamp slot and started all over again , hey presto 30 mins later out she came , thank goodness .

PW
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Joined: 23 Jan 2007, 10:50am
Location: N. Derbys.

Re: stuck seat post

Postby PW » 28 Nov 2010, 1:03am

Ammonia from Boots. It works, I've done it recently.
If at first you don't succeed - cheat!!

Bill D
Posts: 131
Joined: 6 Nov 2008, 5:41am
Location: sunny mid Wales

Re: stuck seat post

Postby Bill D » 1 Dec 2010, 7:48am

I recently freed a stuck alloy seat post in a steel frame. It was my own bike, so the seat was the right height to ride. I took off the seat tube clamp and rode the bike without it for about a month (actually I put it in my seat pack in case the tube came unstuck while I was out riding). Every couple of days I applied household ammonia liquid (bought from our local old fashioned hardware store) around the seat tube at the junction with the frame with an old paintbrush. It was surprising how much of the liquid was able to trickle down between the tubes. One morning, after abut a month of this treatment, I went to get on the bike and noticed that the seat was loose...
I had called in to my LBS for advice. They had said not to get too stressed about it and that with time it would quite likely free itself up. They did offer to take the bike in and free up the tubes, saying that they would use a big vice and a long breaker bar, but that they couldn't guarantee not to break the bike doing it.
Good luck with yours.

Znook
Posts: 1
Joined: 5 Oct 2010, 12:54pm

Re: stuck seat post

Postby Znook » 1 Dec 2010, 10:25am

I'm currently in the process of removing my stuck alloy seat post. So far I've tried the following (in order): Brute force, WD40, Plus-Gas, Coke, Freeze/Heat, Washing Soda (I know, don't laugh), Ammonia and now Caustic Soda.

So far I've put six mixes (4g/120ml) down the tube and it's still not budging. Lots of horrible black gunk coming out so it's definitely working. Now waiting on a new tub of CS before I can begin again. Lesson has been learned; don't leave seat post untouched for 15 odd years.

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Greybeard
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Joined: 1 Oct 2008, 6:48pm
Location: East Yorkshire

Re: stuck seat post

Postby Greybeard » 1 Dec 2010, 2:26pm

Znook wrote:So far I've put six mixes (4g/120ml) down the tube and it's still not budging. Lots of horrible black gunk coming out so it's definitely working. Now waiting on a new tub of CS before I can begin again. Lesson has been learned; don't leave seat post untouched for 15 odd years.


That certainly sounds familiar :roll: Be patient, the ali will dissolve - on a positive note, I'll guarantee that you'll never forget to grease a seatpost again :wink:
Steve - been there, done that and got the rubber gloves :oops:

Wheelnut
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Joined: 13 Feb 2010, 12:02pm
Location: Henley-on-Thames

Re: stuck seat post

Postby Wheelnut » 1 Dec 2010, 3:16pm

Yes, caustic soda will completely dissolve the aluminium. It also dissolves paint. Took me about a week to dissolve an alloy seatpost from a 1950s frame, changing the solution once a day.

Applying heat may well free the seatpost. Yes, alloy does expand more than steel, but that comparative difference in expansion is precisely why it can free the bond. Heat it with a heat gun or blowtorch, allow to cool, and then try freeing it off.

Good luck!

PW
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Joined: 23 Jan 2007, 10:50am
Location: N. Derbys.

Re: stuck seat post

Postby PW » 1 Dec 2010, 5:02pm

Frame upside down, bottom bracket removed, and ammonia poured in from the bottom. Leave overnight. 1 application usually does it, 2 is the most I've needed. The advantage over caustic soda is that you get to use the seatpost again and it doesn't trash the paint. It used to be easier with the high strength stuff you could get as leftovers from drawing office printing machines back in the 80s but household stuff from Boots does work. I've recently done it with both a seatpin and a quill stem seized into a fork steerer.
If at first you don't succeed - cheat!!

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Phil_Lee
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Location: Cambs

Re: stuck seat post

Postby Phil_Lee » 1 Dec 2010, 9:27pm

It should be fairly obvious that if heat will cause the seatpost to expand tighter into the seat tube, extreme cold will cause it to contract.
Therein lies an alternative solution - dry ice.
Other methods of chilling it may be more or less effective, but the combination of availability and achievable temperature makes dry ice a good choice, unless you can get your hands (NOT literally!) on an even more effective refrigerant.
Liquid butane or propane aren't bad, either, but be very careful not to strike a spark if you use one of them!