Thursday, August 07, 2008 - 03:33 PM
Your expression of despair this soon implies you have paid too much attention to reports of others' failure. There hasn't been enough time in research yet, or for a chemical or 2 to act to loosen the bond.
Harry Travis Washington, DC USA
stirred by:
Julie Cleveland <juliecleveland@mac.com>'s message of:
Thursday 07 Aug 08 at 03:17 PM,
On: [CR]Re: Frozen seat post
[echoed below, in part<=1]
-oOo-
>Dear David:
>re seat post
>It's alloy, according to the specs I found online for this bike.
>Does that mean I am stuck with a bike in which I can't lower the
>seat? That stinks! (I didn't of course think to ask these questions,
>stuff that seemed pretty obvious, when corresponding with the guy I
>bought the bike from on ebay).
>I also don't have any of these chemicals, or a workshop, i'm just a
>pianist with a bike she wants to ride!
>Thinking after getting all these replies maybe I gotta not "do it
>myself" and bring it back to the shop.
>is this list for bike shop owners? I don't have any of the stuff
>people are mentioning, I'm just a humble, know-nothing newbie OTS
>rider, hope that's ok.
>--Julie
>On Aug 7, 2008, at 12:43 PM, david.r.stacey@gsk.com wrote:
>>
>>
>> Dear Julie,
>>
>> Oh dear. This is a problem that often kills an old bike. Have a
>> look on Sheldon Browns website for full details, but basically If
>> you have a steel seat post, keep up the WD40 remove the seat bolt
>> completely, use a screwdriver to gently open the frame and get a
>> gorilla to twist the seat tube free.
>>
>> If however it is an alloy seat post, then the thermite reation has
>> occured and the aluminium has reacted and fused together with the
>> steel of the frame. It can be cut out, carefully, rolled up and
>> pulled out, though I have never found this works. I have heard of
>> someone using a threaded bolt as a puller braced against the frame
>> and winding the seat tube out, this is gentler.
>>
>> The last straw is to use 5M sodium hydroxide solution (caustic
>> soda). This will dissolve the aluminium alloy, but not the steel.
>> It also, if you are sloppy strips the paint off your frame and
>> dissolves skin and eyes (and dissolve rims and cranksets), but if
>> you are careful (or a chemist like me) it works where all else has
>> failed. You have to plug the base of the seat tube with clay or blu
>> tack and fill with sodium hydroxide solution 40g/200ml leave it
>> 24hours, flush it out with water and repeat until the metal is
>> paper thin and can be removed.
>>
>> All this is quite extreme and I would ask around for some help with
>> this if you are not familiar with using chemicals. Please be
>> careful and remember, if you want to put the tube down and it is a
>> plain tube type, ask an engineer to cut it shorter and reshape the
>> top (I've done that the other way round for a longer tube). A good
>> engineer can also drill/ream out an old seat post, but he'd have to
>> be a good one.
>>
>> Good luck and be careful!
>>
--
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