Prevention is better than a hernia - stopping an aluminium seatpost sticking in a steel frame

[Smurfy]

if left.long enough it ultimately mayd so, but the process takes much longer than oxidation through emulsification of water and grease. Tis why I use moly, much more inert.

On the topic of dry lubricants
http://en.wikipedia.org/wiki/Dry_lubricant
White Lightning (the chain lube, not the cider!) might be worth a try as a seatpost lubricant, as it contains PTFE and Boron Nitride.

 

[Drago]

Not all grease is water soluble, depends very much on the compound - marine grease is a prime example. Nevertheless, grease is unsuited to the role of anti seize agent, and as good as useless as an anti seize on threads.

If its all you've got and every 6 months or so you're prepared to wipe out the frame and post then it'll do fine. As a long term or fit and forget proposition then the proper stuff is essential.

 

[raleighnut]

Bollocks.

It'll probably corrode those as well.

 

[Drago]

It'll probably corrode those as well.

it'll corrode Lance's in half the time.

 

[KneesUp]

Lots of interesting comments

The seat post in question is a lot easier now. I gave it a good squirt of WD-40 and left it 40 minutes to carry on dissolving whatever the hell was in the tube.

I then cleaned out as far as I could reach with kitchen roll, and out came grey sludge with flecks of aluminium in it - no doubt from the effort of me getting it out earlier. In a quest to clean further down I wrapped a cloth around a broom handle and poked that down a few times, before it occurred to me the cloth might get stuck. I then rattled the broom handle around the tube a bit and it did get out some gunk. Then I pried the slot apart a little with a screwdriver. I then reduced friction with all I had to hand - some Vaseline that I think is mine bought for the little battery plug for my front light - if not then I've got grey, aluminium smudges in someone's Vaseline. It seems much better - when I thought it was fine you couldn't put it down without twisting it, but now you can get it down with a firm push.

This is why I like this forum - I thought it might be a daft question, but I've learned several things, including that it's not normal to have a seat post that you can't move easily and much advice about how to prevent a recurrence. Thanks all.

 

[fatboy123cycling]

Remove seat post and clean - if any burrs remove using fine emery cloth - clean and dry. Clean inside the frame with a bottle brush, then clean and dry with a rag. Then apply some anti - seize compound. Can be Copper Slip as suggested above or Zinc based anti - seize compound. Check regularly depending on your type of riding - or the weather.

 

[Berties]

my post on the croix de fer is stuck like muck to a blanket I've had the clamp loosened and gt85 spray on it daily but i fear a hacksaw blade is nearing,i have also fitted full length mud guards,posts can be taken out by so called specialised companies but the cost is about £50

 

[Piemaster]

marine grease

Depends what you mean by marine grease. I could probably lay my hands on a dozen different types with a quick walk around the boat I'm on now. Everything from a coupling grease that can almost be poured to a very waterproof wire rope grease that sticks like the proverbial to a blanket.
Agree with you over a Molykote grease for the seatpost - but then theres a few different types of them too. Anti-seize compound has always worked well for me.

 

[Yellow Saddle]

[QUOTE 3528148, member: 9609"]but would they not expand into salts and cause it all to seize up.

Incidentally, I smeared some chainsaw oil on mine when I put it in a few years back, have just checked now and it was OK to move!
I use chainsaw oil for everything, cause thats whats in my oil can[/QUOTE]
It depends on the size of the resultant molecule. The bigger the product of the galvanic reaction, the more it will freeze the seatpost. The concept of the copper (or nickel or whatever is chosen based on between what materials it will be used), like Drago said is to provide a sacrificial anode. In other words, instead of the steel and aluminium post ad frame to be anode and cathode, the copper becomes the anode and gets used up. I would imagine that the size of the original copper flakes and the resultant copper salt is more or less equal.

 

[Yellow Saddle]

my post on the croix de fer is stuck like muck to a blanket I've had the clamp loosened and gt85 spray on it daily but i fear a hacksaw blade is nearing,i have also fitted full length mud guards,posts can be taken out by so called specialised companies but the cost is about £50

Yup, spraying stuff on doesn't work. You can try the caustic soda bomb (I'm still wincing and feel little itchy splotches on my face and hands) or all the stuff you can read about on the internet ranging from Coke to organic lime juice, nothing works. Keep this recipe for when you decide to take the plunge:

1) Get a new seatpost now. Look out for an attractive bargain, buy it and store it.
2) Saw the existing post off 25mm above the frame collar.
3) Remove the hacksaw blade from the saw frame and wrap a cloth around one end. Keep beer on hand and swallow some patience. This is not quick.
4) Have a nice small torch handy.
5) Saw vertically through the remainder of the post stuck inside the frame. The idea is to saw a slot right through the post wall along the length of the post. You will score the frame but be patient, look frequently and adjust your aim as needed.
6) Once you are right through (you'll notice a different colour come through as you nick the frame, take a sip of beer.
7) Now take a pair of standard pliers or one of those hinged pliers (not longnose, you will destroy it) and grip the seat post stubby right next to the slot and wind the post up inwards. By that I mean you open it like an old fashioned sardine can.
8) As soon as the tube bends inwards, pressure is immediately relieved and it will come out in one piece. This seems surprising to most people but remember, it is stuck not through adhesion but through swelling. There is no bond between post and frame.
9) Clean as described above and fit your new post using copper compound or similar.
10) Promise yourself you will remove and check it every six months.

 

[Yellow Saddle]

This seatpost was supposedly "Carbon wrapped" but actually nothing other than an aluminium post with some sort of carbon-look sticker on. It was inside a carbon frame. The silver bit is the part of the post that was stuck inside the frame. The corrosion took place underneath the "carbon" skin which stayed behind when the post came out. Note the while crystals of aluminium salt.

 

[Berties]

Yup, spraying stuff on doesn't work. You can try the caustic soda bomb (I'm still wincing and feel little itchy splotches on my face and hands) or all the stuff you can read about on the internet ranging from Coke to organic lime juice, nothing works. Keep this recipe for when you decide to take the plunge:

1) Get a new seatpost now. Look out for an attractive bargain, buy it and store it.
2) Saw the existing post off 25mm above the frame collar.
3) Remove the hacksaw blade from the saw frame and wrap a cloth around one end. Keep beer on hand and swallow some patience. This is not quick.
4) Have a nice small torch handy.
5) Saw vertically through the remainder of the post stuck inside the frame. The idea is to saw a slot right through the post wall along the length of the post. You will score the frame but be patient, look frequently and adjust your aim as needed.
6) Once you are right through (you'll notice a different colour come through as you nick the frame, take a sip of beer.
7) Now take a pair of standard pliers or one of those hinged pliers (not longnose, you will destroy it) and grip the seat post stubby right next to the slot and wind the post up inwards. By that I mean you open it like an old fashioned sardine can.
8) As soon as the tube bends inwards, pressure is immediately relieved and it will come out in one piece. This seems surprising to most people but remember, it is stuck not through adhesion but through swelling. There is no bond between post and frame.
9) Clean as described above and fit your new post using copper compound or similar.
10) Promise yourself you will remove and check it every six months.

Thank you for that,I know it needs to be done and will , get it done when in off that bike for the warmer weather

 

[Globalti]

Try turning the bike upside-down and reaming the seat tube out with a piece of wet & dry paper pushed in with a wooden spoon handle.