The only thing that has ever defeated me...
...is an aluminium bike headset and stem seemingly fused into a vintage steel bike frame. I've tried yanking, WD40, bathing it in Cola for a week, sticking it in a vice.

Last ditch is to break out the hacksaw blades, chop the top off and spend a merry few hours slowly cutting through the aluminium stem from the inside.

Unless any of you have a better solution?
(Monchberter Can't go wrong with Doom, Fri 11 Mar 2011, 14:03, 20 replies)

screwdriver in the headtube against the headset and massive big hammer?
tap it around etc to get it out?

and lots of wd40
( zulu eh?, Fri 11 Mar 2011, 14:09, closed)

Big hammer

( emvee cruor deo cruoris, Fri 11 Mar 2011, 14:09, closed)

or a local bike shop?
get them to do it?
( zulu eh?, Fri 11 Mar 2011, 14:17, closed)

Try
heating it up. Worked for my headset after it seized in a pavement based collision.
(tickles, Fri 11 Mar 2011, 14:18, closed)

^seconded
I had a similar problem and was sorted after a trip to the local blacksmith
(Studentken is looking for motivation on, Fri 11 Mar 2011, 14:26, closed)

local blacksmith?

( Ring Of Fire A petty, drooling belming butthurt retard., Fri 11 Mar 2011, 14:36, closed)

He lives in Gretna.
He's now married to a Cooper classic.
( Dr. Shambolic je suis charlie, Fri 11 Mar 2011, 14:43, closed)

Coefficient of thermal expansion...
.. of aluminium is 22 - steel is 13.

If you cool it down the aluminium will shrink at twice the rate of the steel.
( Ugi , it's a game of give and cake, Fri 11 Mar 2011, 14:57, closed)

So...
heating the whole lot up, then rapidly cooling the aluminum components would potentially free them?
(Monchberter Can't go wrong with Doom, Fri 11 Mar 2011, 15:11, closed)

that sounds like a good solution
I suggest using first a blowtorch and then a CO2 fire extinguisher
( Vipros. clever got me this far, then tricky got me in, Fri 11 Mar 2011, 15:17, closed)

*Checks man drawer*
Nope, can't see a blowtorch or CO2 extinguisher, what about heating it on the cooker and plunging it in the sink?
(Monchberter Can't go wrong with Doom, Fri 11 Mar 2011, 15:22, closed)

What's for dinner?
Could work - fill the sink with iced water, heat the whole area and the plunge the aluminium part into the ice.
( Ugi , it's a game of give and cake, Fri 11 Mar 2011, 15:24, closed)

Maybe....
The problem is that as you heat it up the joint will get tighter (the aluminium will expand more than the steel). However, aluminium is very conducting - much more so that steel and so you may be able to free it by then cooling the aluminium part quickly while the steel stays hot.

The other approach is to cool the whole area. When the whole lot cools, the aluminium will shrink more than the steel. Not too sure whether practical methods of cooling it will be enough thou'.


Edit vipros' method of a CO2 extinguisher might do it: -78'C. Wear gloves.
( Ugi , it's a game of give and cake, Fri 11 Mar 2011, 15:21, closed)

Now I have a vision
Of someone trying to wedge a bike into a Chest Freezer. I have often made installing bearing shells easier by putting them into the freezer overnight first.
(Mackeson_drinker, Sat 12 Mar 2011, 7:16, closed)

Had the same problem recently - nearly went donw the saw route, but having done that on a seat post already, didn't fancy it.

It's actually pretty simple to sort. Screw in the long top tightening bolt slightly so it bites on the wedge inside the steerer tube. Then, give the top of the bolt a few taps with a mallet and it should come free. simple.

Check picture 2 here: www.bikeradar.com/road/gear/article/workshop-how-to-service-a-headset-22225

Donutboy
(donutboy, Fri 11 Mar 2011, 15:22, closed)

CIIJASIIE

( Dr. Shambolic je suis charlie, Fri 11 Mar 2011, 15:34, closed)

Indeed heat and cold are the answer.
Pipe freezing spray would be good i reckon.
( blaireau69 , the Cumbrian Travis Bickle., Fri 11 Mar 2011, 15:50, closed)

Well?
Come on..we need to know. You've had most of the weekend!
(Mao's stepson is doing his bit for East/West relation's, Sun 13 Mar 2011, 9:15, closed)

^This

( Ugi , it's a game of give and cake, Mon 14 Mar 2011, 11:54, closed)

MBUK
In the way distant past I seem to remember a letter to Mountain Biking UK about how to free an aluminium seat post seized in a steel frame. The answers were:

1: Lots of WD40, then put the frame in a vice and wrench the post around with a pair of mole grips.

2: Cut the post off and use a saw blade to cut the post that's stuck in the frame into little bits.

3: Invent a time machine and go back and grease the post like you should have done in the first place.

Let us know how #3 goes by posting in last week's QOTW.
(flimflam_machine, Wed 16 Mar 2011, 14:44, closed)