frozen seat post
Alan Wenger
How does one loosen a frozen seat post (aluminum post and
chromoly seat tube)? HELP!
Msanl
When all else fails, turn your bike upside down in the repair stand (or
rig it up to stay upside down if you don't have a repair stand), remove
the bottom bracket, and pour half a can of coke into the seat tube. Allow
it to sit for 30-40 minutes and you may be in luck. this is no joke. Have
done it successfully many times while working @ a LBS.
Good luck.
-Mark
Sheldon Brown
Alan Wenger queried:
>
> How does one loosen a frozen seat post (aluminum post and
> chromoly seat tube)? HELP!
I have a fair-sized article on this subject on my Web site:
http://www.sheldonbrown.com/biz/hub/stuck_seatposts.html
Sheldon "Ungrrrrrrrrrrrrrh!" Brown
Newtonville, Massachusetts
+-------------------------------------------------------------+
| If brute force doesn't work, you're not using enough! |
| --Bob Simon
|
+-------------------------------------------------------------+
http://www.sheldonbrown.com/biz/hub/
Harris Cyclery, West Newton, Massachusetts
(617) 244-1040 FAX 244-1041
SICILIAM
Sheldon Brown <Capt...@sheldonbrown.com> wrote:
Try amonia in seat tube this will break down the aluminum oxidation.
JYates605
You can try penatrating oil, like WD-40, but it usually won't work well in
situations like this with such a tight gap, and lots of surface area. You
may have rust, galvanic corrosion, or both. The best method I know of is
heat. A hair dryer is quick and easy to try, but rarely hot enough. An
industrial heat gun (goes to aroung 900 degrees) like automotive trim
shops use is the trick. It might cost you something like 50 bucks, but
then you can install vinyl roofs on cars! As you heat, the dissimilar
metals will expand at different rates. Heat progressively.....you won't
harm the post or frame, but the paint could be damaged.
You may also need more leverage than your saddle can supply. If so, a
plummer's wrench will give more, but ruin the post. Better option? Go to
an automotive parts store and buy a belt-style oil filter remover. It's
made from a piece if seatbelt and a square rod. A regular 3/8" drive
ratchet or breaker bar fits in the end. Remove the saddle, slide the belt
around the post, take up the slack in the belt, and turn it just like a
socket. This mother can exert enough force to crumple really thin tubing,
so if this does not break it loose, you'll have to resort to cutting off
the head and filling/cutting from the inside out.
Good luck,
Jon Schaer
American Classic
Sheldon Brown
Jon Schaer suggested:
> You can try penatrating oil, like WD-40, but it usually won't work well
WD-40 is not penetrating oil; Liquid Wrench is penetrating oil. It is
designed for dealing with rust, not aluminum corrosion. As I mention in
my article, ammonia is the ticket for aluminum corrosion.
> ...The best method I know of is
> heat...As you heat, the dissimilar metals will expand at different rates.
Alan mentioned that his bike has an aluminum seatpost in a steel frame.
Since aluminum's coefficient of expansion is twice that of steel, heat
is counterproductive for aluminum parts stuck inside of steel ones.
Chilling, on the other hand, often does the trick.
> You may also need more leverage than your saddle can supply. If so, a
> plummer's wrench will give more, but ruin the post. Better option? Go to
> an automotive parts store and buy a belt-style oil filter remover. It's
> made from a piece if seatbelt and a square rod. A regular 3/8" drive
> ratchet or breaker bar fits in the end. Remove the saddle, slide the belt
> around the post, take up the slack in the belt, and turn it just like a
> socket. This mother can exert enough force to crumple really thin tubing,
> so if this does not break it loose, you'll have to resort to cutting off
> the head and filling/cutting from the inside out.
Or better yet, go to your local bike shop and get a cheapo saddle from
the
bargain bin...nothing attaches so well to a seatpost as a saddle.
Sheldon "http://www.sheldonbrown.com/biz/hub/stuck_seatposts.html" Brown
Newtonville, Massachusetts
+-------------------------------------------------------------+
| I often quote myself. It adds spice to my conversation. |
| --George Benard Shaw |
djw
This is what we did (true story)
1) First find some BIG friends
2) Take off the seat & bolts etc, hopefully it has flush sides so you
can:
3) Turn bike upside down and put seat post in a big solid bench vise.
4) Try to twist the frame on the seatpost. Try harder. Get a few more
people and try some more.
It twists! Yippee! The coast is clear: now you are ready for step 5)
5) Get the biggest strongest guys to stand up on the bench, and they
pull upwards as you twist the bike on the seatpost. Progress will seem
slow, but progress is progress, we're not talking microchips here dude.
Eventually, a few minutes, beers, or curses later, the frame will be
pulled off the post, and you have learned a valuable lesson about
greating components before installation in clamps, galvanic corrosion,
and the value of good friends who will help you fix some of life's
easier to solve problems.
Ride hard, and no coasting on the descents!
doug williams
Montreal
PS, the tip is courtesy Chuck Riordan @ Velo Brome (quebec canada), I
was the friend who pulled upwards.
NMilhaupt
If the vice trick for removing the stuck post doesn't work (try it, it
usually does), you can cut the top section off of the post, and then use a
jab hacksaw to make a few cuts along the length of the post, then use a
hammer and punch to drive the pieces off.
Nick
Milhaupts Bicycle Works
Appleton WI
ro...@sk.sympatico.ca
In <5cmilh$mbk$1...@mhafc.production.compuserve.com>, Alan Wenger <73472...@CompuServe.COM> writes:
>How does one loosen a frozen seat post (aluminum post and
>chromoly seat tube)? HELP!
your seat tube, you could squirt the vinegar through there rather than taking apart
the bottom bracket.
JYates605
Seldon Brown wrote;
>WD-40 is not penetrating oil; Liquid Wrench is penetrating oil. It is
>designed for dealing with rust, not aluminum corrosion. As I mention in
>my article, ammonia is the ticket for aluminum corrosion.
Maybe it's just a case of semantics, but it's funny. For not being a
penatrating oil, WD-40 works awful well as a penatrating oil. But I'm
always willing to learn. Can you offer any chemical basis for the
"ammonia" solution?
>Alan mentioned that his bike has an aluminum seatpost in a steel frame.
>Since aluminum's coefficient of expansion is twice that of steel, heat
>is counterproductive for aluminum parts stuck inside of steel ones.
>Chilling, on the other hand, often does the trick.
It's not counterproductive. It works. Expansion or contraction, it doesn't
matter, because the isn't meant to be permanant. The relative movement
between the surfaces is what is important. If you have ever worked in
automotive mechanics, you would know that heat and flame have saved many a
frustrated wrench swinger. Auto mechanics have been using this trick for
as long as there have been autos.
>Or better yet, go to your local bike shop and get a cheapo saddle from
>the
>bargain bin...nothing attaches so well to a seatpost as a saddle.
You must not have read the preceding paragraph very well. Explain how a
cheapo saddle is going to offer more leverage that whatever saddle he has
now? I was offering suggestions for methods that have worked for me that
offer MORE leverage (i.e. a greater distance from the point of rotation;
i.e. torque). And believe me, the oil filter remover I described would
provide a considerably better grip, and allow the application of more
torque, than a saddle in its clamp. Again, if you work on cars, buy one of
these these things and see for yourself.
Hope no hard feelings? I simply offer what has worked for me in the past.
No "truth" is being professed here. I would be interested, though, to hear
what soultion actually worked.
Jon Schaer
American Classic
Alan Walker
In article <32F37D...@netcom.ca>, djw <dj...@netcom.ca> says:
(snip)
>4) Try to twist the frame on the seatpost. Try harder. Get a few more
>people and try some more.
>
>It twists! Yippee! The coast is clear: now you are ready for step 5)
Watch out. When he says "It", he might mean the frame! I have seen a
frame bend without budging the seat post. If you are careful, you can
cut the top off the post, then cut a slot by putting a hacksaw blade
down the inside. You might even have to cut two slots. Set aside a
whole evening after work, and play some soothing music.
Another hint: there is no lubricant in the galaxy that will loosen a
well corroded seat post.
have fun
AW
Sheldon Brown
Jon Schaer quoted me:
>
> >WD-40 is not penetrating oil; Liquid Wrench is penetrating oil. It is
> >designed for dealing with rust, not aluminum corrosion. As I mention in
> >my article, ammonia is the ticket for aluminum corrosion.
and demurred:
> Maybe it's just a case of semantics, but it's funny. For not being a
> penatrating oil, WD-40 works awful well as a penatrating oil.
Any oil is better than no oil, but oils designed particularly to be
penetrating oils are thinner, and, I believe, have special additives
for this purpose (which may detract from their performance as
lubricants)
> But I'm
> always willing to learn. Can you offer any chemical basis for the
> "ammonia" solution?
Sorry, I'm a mechanic, not a chemist.
> >Alan mentioned that his bike has an aluminum seatpost in a steel frame.
>
> >Since aluminum's coefficient of expansion is twice that of steel, heat
> >is counterproductive for aluminum parts stuck inside of steel ones.
>
> >Chilling, on the other hand, often does the trick.
>
> It's not counterproductive. It works. Expansion or contraction, it doesn't
> matter, because the isn't meant to be permanant. The relative movement
> between the surfaces is what is important.
This can indeed work in some cases, "counerproductive" may have been an
overstatement.
> If you have ever worked in
> automotive mechanics, you would know that heat and flame have saved many a
> frustrated wrench swinger. Auto mechanics have been using this trick for
> as long as there have been autos.
Yes, but how often do they have to deal with _aluminum_ parts stuck
inside
of steel parts?
> >Or better yet, go to your local bike shop and get a cheapo saddle from
> >the
> >bargain bin...nothing attaches so well to a seatpost as a saddle.
>
> You must not have read the preceding paragraph very well. Explain how a
> cheapo saddle is going to offer more leverage that whatever saddle he has
> now?
It doesn't, but if you mangle up a $5 yellow BMX saddle by hitting it
with
a rubber mallet, you won't feel as bad as you would if you trashed your
Brooks Swallow.
> I was offering suggestions for methods that have worked for me that
> offer MORE leverage (i.e. a greater distance from the point of rotation;
> i.e. torque). And believe me, the oil filter remover I described would
> provide a considerably better grip, and allow the application of more
> torque, than a saddle in its clamp. Again, if you work on cars, buy one of
> these these things and see for yourself.
I don't work on cars, oil filter wrenches I have seen don't go down
nearly
small enough to fit a seatpost. Although the first priority in these
jobs
is saving the frame, I would also like to save the seatpost. I have
seen
many seatposts un-necessarily ruined by Stillsons, Vice-Grips, et. al.,
which is why I recommend a saddle.
> Hope no hard feelings?
Soitenly not!
Sheldon "Let's Twist Again, Like We Did Last Summer" Brown
Newtonville, Massachusetts
+------------------------------------------------------+
| A billion here, a couple of billion there -- |
| first thing you know it adds up to be real money. |
| --Sen. Everett McKinley Dirksen |
+------------------------------------------------------+
Bob Schwartz
Jon Schaer wrote, following a post from Sheldon Brown:
> But I'm
> always willing to learn. Can you offer any chemical basis for the
> "ammonia" solution?
And Sheldon bailed, sounding like Leonard McCoy:
> Sorry, I'm a mechanic, not a chemist.
I asked a chemist. While she was unwilling to state exactly
what was reacting and why without researching it, she did say
that aluminum will react and dissolve in basic solutions, and
that ammonium hydroxide was a basic solution. So she thought
that probably what happens is that the oxide reacts and forms an
ammonium salt, removing the layer of oxide from the seatpost.
If ammonia works then there are probably lots of other things
that would work as well e.g. Drano but are not as easy to deal
with.
She did say that you wouldn't want to do this repeatedly to free
an aluminum seatpost in an aluminum seat tube as you would
eventually change the inner diameter of the seat tube, although
anyone that repeatedly inserts an ungreased seatpost probably
has other more serious problems in life. But you wouldn't want
to invert the bike and pour ammonia in the bottom bracket and
let it sit in the seat tube.
Bob Schwartz
bsch...@cray.com
Kristan Roberge
Bob Schwartz <bsch...@cray.com> wrote:
>
> Jon Schaer wrote, following a post from Sheldon Brown:
> > But I'm
> > always willing to learn. Can you offer any chemical basis for the
> > "ammonia" solution?
>
> And Sheldon bailed, sounding like Leonard McCoy:
> > Sorry, I'm a mechanic, not a chemist.
>
> I asked a chemist. While she was unwilling to state exactly
> what was reacting and why without researching it, she did say
> that aluminum will react and dissolve in basic solutions, and
> that ammonium hydroxide was a basic solution. So she thought
> that probably what happens is that the oxide reacts and forms an
> ammonium salt, removing the layer of oxide from the seatpost.
> If ammonia works then there are probably lots of other things
> that would work as well e.g. Drano but are not as easy to deal
> with.
>
Extra-Strength EasyOff Oven-Cleaner (the Yellow container, NOT the
blue container) works great for this purpose. Also useful in
removing the annodized from aluminum parts (The ONLY way to get rid
of that disgusting purple on alot of stuff).
Sheldon Brown
Bob Schwartz wrote:
>
> Jon Schaer wrote, following a post from Sheldon Brown:
> > But I'm
> > always willing to learn. Can you offer any chemical basis for the
> > "ammonia" solution?
>
> And Sheldon bailed, sounding like Leonard McCoy:
> > Sorry, I'm a mechanic, not a chemist.
Well, should I have pontificated and thorized and made
up a vaguely plausible answer about a subject that I don't
know much about? That is not allowed in this newsgroup! ;-)
Sheldon "It Has To Do With Ions, Yeah, That's It, Ions...And
Tachyon Particles" Brown
Neutronville, Massachusetts
+---------------------------------------------------+
| I was gratified to be able to answer promptly, |
| and I did. I said I didn't know. |
| -- Mark Twain |
+---------------------------------------------------+
poss
Sheldon knows how: in minute detail too. Check out his site: he's sure
to have posted with it's URL somewhere here.
tbg...@aol.com
In article <5d848r$n...@news.istar.ca>, Kristan Roberge <Krob...@magi.com>
writes:
>Extra-Strength EasyOff Oven-Cleaner (the Yellow container, NOT the
>blue container) works great for this purpose. Also useful in
>removing the annodized from aluminum parts (The ONLY way to get rid
>of that disgusting purple on alot of stuff).
>
Drano was mentioned in the post that Kristan quoted, I would strongly
suggest you NOT use Drano for this. Drano is NaOH with aluminum shavings
in it. The foaming reaction of Drano is caused by a reaction between the
two and you could get splattered with a strong alkali. Since we are
dealing with an aluminum alloy seat post here the NaOH might well loosen
(or disolve) the thing but it could also do a real number on the frame . .
. especially if it is aluminum. If I got to the point were I was going to
try something like this I'd have protective glasses on and a nice jug of
vinegar to neutralize the alkali (especially if I got some on me).
If all else failed (I'd try Sheldon's web page stuff first) I might try
soaking it with baking soda over night, it is a mild alkali and might do
the job. Washing soda or Kirstan's suggested oven cleaner would be next
and then . . . maybe something stronger.
Do any of you shop owners have a broken seat post that you'd sacrifice by
soaking in a solution of NaOH (Lye) to see what would happen?
Tom Gibb <TBG...@aol.com>
Matt Wenham
I recently freed my stuck seatpost by
1) Taking the seatbolt right off the bike
2) *Gently* prising the seat clamp apart a little
3) Dripping a lot of tri-flow down the gap at the top between the
seat post and seat tube.
4) Leaving for a few hours for the tri-flow to penetrate.
That did it, an I found that over half the inserted length of the
seatpost had corroded. The tri-flow had penetrated about halfway down
the corroded part of the post before I could losen it. I cleaned up the
post and refitted with lots of copper grease so that it (hopefully)
won't happen again.
Matt...
David Pottage
Sheldon Brown wrote:
>
> Bob Schwartz wrote:
>>
>> Jon Schaer wrote, following a post from Sheldon Brown:
>>> But I'm
>>> always willing to learn. Can you offer any chemical basis for the
>>> "ammonia" solution?
>>
>> And Sheldon bailed, sounding like Leonard McCoy:
>>> Sorry, I'm a mechanic, not a chemist.
>
> Well, should I have pontificated and thorized and made
> up a vaguely plausible answer about a subject that I don't
> know much about? That is not allowed in this newsgroup! ;-)
I am a chemist, so I can provide an explanation.
Most metals, Steel & aluminum included react with acids (H+ ions
(protons)). Aluminum is unusual in that it also reacts with alkali (OH-
ions (Hydroxyl ions)). This is why you should not use caustic soda to
clean aluminum pans. Other metals including do not reacat with alkali,
or in some cases are protected from rust (For example, the steel
reenforcement in very alkali concrete).
Ammonia solution is a weak alkali, so it will disolve aluminum, but as
it is weak, it is not very fast or aggresive, so it tends to go
selectively for the aluminum oxide that is jaming your Alu seatpost to
your steel frame. Once this layer is disolved, the seatpost should slide
out easily. It would be a good idea to rinse it, but you will probably
do that anyway because of the smell.
meanwhile, your expensive iron (of Ti) frame is untouched by the amonia.
Needless to say, this should not be done with Aluminum frames.
That's your chemical explanation Bob, are you satisfied now?
--
David Pottage
1st Year Chemistry Postgraduate Student, University of Southampton,
Southampton SO17 1BJ, U.K. email: d.e.p...@soton.ac.uk
Melissa & Jim
David Pottage <d.e.p...@soton.ac.uk> wrote:
I was with you up to the point of letting the ammonia leach away the
alum oxide. Al2O3 is just about one of the most inert compounds you
can imagine. I don't think it will react with anything at room temp,
and ammonia is just not gonna do anything to it.
The ammonia may eat away at a bit of the aluminum, but when it is
working from the edge of a long siezed joint like this, especially one
that probably has been already soaked in various kinds of petroleum
products, I think it very unlikely that it will accomplish anything.
Jim
---------------------------------------------------------------------
Melissa Kepner Jim Adney
mgke...@facstaff.wisc.edu jim....@mpcug.com
Laura Kepner-Adney
Madison, Wisconsin
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