Stuck seatpost - blowtorch technique advice please

Aunty Rubbish · June 2007

Hello all.
I have a stuck ally post in a steel frame. I own a blowtorch. However how, precisely, do I deploy said implement without burning off paintwork etc?

I know the stuck seatpost issue is a perennial favourite round here but I'm a bit fuzzy on technique rather than method.
Cheers
Chuffy

Chuffy

monty_dogcp · June 2007

I don't think you'll find you'll be able to use the blowtorch without damage to the paintwork! A hot air gun is another technique, but it will still soften the paint.

Unknown · June 2007

Penetrating oil?

McBain_v1 · June 2007

Why would you want to heat the thing up - that makes things expand doesn't it - so presumably it will wedge itself in even tighter [?] Unless you are only going to heat the seat tube and leave the allow seat post as cold as possible (wrap in ice bags).

I'd stick with some penetrating oil first... although my current dilemma is that I have the opposite problem - seat post keeps creeping inexorably downward whilst out on rides...

What do I ride? Now that's an Enigma

Aunty Rubbish · June 2007

I've tried all the usual techniques my impressionistic friend. The only ones left are a length of scaffolding pole, with the attendant risk of damaging the seat tube, or blowtorch.
Cheers,
Chuffy

Chuffy

Aunty Rubbish · June 2007

Steel and aluminium expand at different rates (iirc) so heating will expand the steel more than the ally.

Chuffy

McBain_v1 · June 2007

Excuse my metallurgical ignorance [:I]

What do I ride? Now that's an Enigma

chewa · June 2007

I've always found judicious use of boiling water enough to cause steel to expand enough to free off.

You could take the bb off, block any holes in the seatpost, turn bike upside down, pour oil into the seattube, leave overnight then apply boiling water.

Blowtorch, hot air gun etc will damage the paint.

plus je vois les hommes, plus j'admire les chiens

Yorkshireman · June 2007

I suppose that you have tried Sheldon Brown :- "Aluminum seatposts frequently become stuck by corrosion also, and penetrating oil is almost useless against aluminum oxide. Fortunately, aluminum oxide can be dissolved like magic by using ammonia."
More tips here :-
http://sheldonbrown.com/stuck-seatposts.html

Colin N.

Lincolnshire is mostly flat... but the wind is mostly in your face!

Unknown · June 2007

Penetrating oil / boiling water / stick the post in a vice and twist?

S

MattBlackBigBoysBMX · June 2007

Use a proper penetrating oil like Plus Gas, for as long as you can be bothered, stick seat in vice and twist the whole bike.
Done this dozens of times (not on my bikes!) and it's never failed.
Don't use WD40 or 3in1, they're useless, get Plus Gas.
HTH.[:)]

Wheelies ARE cool.

Aunty Rubbish · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by McBain_v1

Excuse my metallurgical ignorance [:I]<hr height="1" noshade id="quote"></blockquote id="quote">
You're excused. Unhang that shamed head laddie.[^]
Because according to Sheldon, I'm talking out of my arse...[:I] "The torch technique is worse than useless when you are dealing with an aluminum seatpost stuck in a steel or titanium frame, because aluminum expands twice as much as steel"[:o)]

Cheers all, will have a truffle about for Plus Gas, ammonia and a bloody big crowbar....
Chuffy

Chuffy

Flying_Monkey · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Aunty Rubbish

Steel and aluminium expand at different rates (iirc) so heating will expand the steel more than the ally.
<hr height="1" noshade id="quote"></blockquote id="quote">

"The torch technique is worse than useless when you are dealing with an aluminum seatpost stuck in a steel or titanium frame, because aluminum expands twice as much as steel, and 2 1/2 times as much as titanium for the same increase in temperature. In fact, the exact opposite technique will often do the trick for aluminum seatposts--cool the seatpost down as rapidly as possible. The contents of a CO2 tire inflation cartridge applied inside the seatpost can shrink it down just enough to do the trick."

Sheldon again...

Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety

Aunty Rubbish · June 2007

I refer the honourable gentlemonkey to the response I gave some moments ago...[;)]

Chuffy

Flying_Monkey · June 2007

ooops - simultaneous posting...

Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety

woody-som · June 2007

use the CO2 method above, ZINN recomends this as a workable solution.

robgul · June 2007

Hey Chuffy - try the Sheldon technique but pour Coca Cola in instead of ammonia .... or the "grasp the seat tube in a big bench vice and use the frame (gently) as a lever" has worked for me.

Rob (BTW your No 1 admirer, Jan, led a Shakespokes ride last night ... asked if I had heard from you)

MacRide 2007 - 9 Sept at Stratford-on-Avon - raising money for Macmillan Cancer Support - 25/50 miles - & for 2007 MacRide 100Km (Audax style) Details: www.macride.org.uk

Rides at Stratford-on-Avon : www.shakespokes.org.uk - trivia at www.beewee.co.uk
----
FGG 3726

david 142 · June 2007

Well, if its really stubborn, and your really concerned about your paintwork, try applying heat to the seatpin. Get it somewhere between "too hot to touch" and "glow in the dark" and then just let it cool down again. Sometimes the differential expansion that you would get even if both pin and frame are steel is enough to crack a corrosive bond. For good measure you could apply penetrating oil as it cools - just wait for it to cool below the flash point!

bikerbill · June 2007

A fizzy cola type drink was recommended to me just this afternoon as a penetrating and easing fluid. That or Plus Gas, and this was from our maintenance guys at work. Must be the acid in the drink that does it, or is the bubbles?

Bill

.............................

High as a mountain and cool as a breeze.

Bagonabike · June 2007

Alternatively m'dear, you could go to the bike shop and pay them a tenner to free it up, just like you had to last year [:D]

mister oy · June 2007

I used caustic soda to free my aluminium stem from my steel Alpinestars fork. I had to saw the stem to free the forks from the frame. I tried the coke method (which has worked on other bits before) and the usual oils/lubes etc but they didn't do the job.

It took about 48 hours with a couple of changes of caustic to do it, but it came out in the end by itself almost. Put a table spoon of crystals in the frame and add hot water. I used candle wax to block the end. You can here it fizzing away, it literally melts the aluminium. It had been stuck there for about 5 years, (the seatpost is still stuck - that hasn't moved in about 15 years [:0])
I got the caustic soda from B&Q for a couple of quid.

Be VERY careful with it cos it's nasty stuff and....

DON'T TRY IT WITH AN ALUMINIUM FRAME!!!!!!

Aunty Rubbish · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bikerbillpenetrating and easing fluid<hr height="1" noshade id="quote"></blockquote id="quote">
Sounds like seven pints of snakebite and black to me....[}:)]

Might try the coke trick over the weekend...

Chuffy

The good doctor · June 2007

I have just this last week tried everything Sheldon Brown advocated but to no avail. I e mailed him via the web site and said I'd used wd40 his reply was to use proper penetrating oil cos wd40 is not up to the job.
I have a friend who runs a car parts business and he mentioned the plus gas oil so I'll try that but i like the sound of the caustic soda method as well.
Let me know how how you get on.

John

Stuck seatpost - blowtorch technique advice please

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