Stuck seatpost!

[niloc]

While trying to identify the cause of an annoying click I have regreased my saddle clamp and was about to check the seatpost. It is an alloy seatpost in a steel MTB frame. Unfortunately, despite being greased, I have found that it is stuck in the seat tube. I have slightly prized the frame coupling apart to apply some penetrating oil and am hoping! and assume that it not the cause of the annoying click.. But does anyone have any useful suggestions how to loosen the seatpost, which are likely to work?

[Jdsk]

"14 Ways to Unstick a Seatpost":
https://sheldonbrown.com/stuck-seatposts.html

Keep it soaked in penetrating fluid while you're reading that!

Jonathan

[Vetus Ossa]

Been there, ammonia worked for me.

[rjb]

I had a frame given to me after an annoying click which the previous owner thought was the bottom bracket. After changing it and not curing it he passed it to me completely frustrated. Turned out to be a stuck seat post which I managed to free off by soaking with penetrating oil. Alloy pin in a steel frame.

[JohnMorgan]

On the subject of ‘annoying clicks’, you might want to check any cable ends hitting rotating cranks . . .

[niloc]

Been there, ammonia worked for me

What strength ammonia? and did you just drip it in from the seat lugs?
Did you have to dis-assemble the bike?

[Vetus Ossa]

Been there, ammonia worked for me

What strength ammonia? and did you just drip it in from the seat lugs?
Did you have to dis-assemble the bike?

Bought the ammonia from boots, the stuff we used for soaking nappies in in the olden days.
Here’s what I did…
Remove bottom bracket, turn the bike upside down and pour the ammonia in the seat tube.
Leave for as long as your patience will allow, I left mine for a week, drain off the ammonia and use something to turn the stuck seatpost with, I used a friends vice. A word of warning this stuff stinks so do it somewhere where it won’t be a nuisance.
As stuck seatpost go mine was very stuck, I tried many different ways to free it. If it’s an aluminium seatpost in a steel frame penetrating oil won’t look at it.

[rareposter]

Been there, ammonia worked for me

What strength ammonia? and did you just drip it in from the seat lugs?
Did you have to dis-assemble the bike?

I'd avoid the chemical options for as long as possible to be honest. Partly because the "ammonia" you can buy in the public domain is pitifully weak but it's still very messy and smelly. And yes, the bike will need a complete total strip down, you don't want to ammonia on any other alloy parts.

Clamp the seatpost tightly then twist the frame around it. You could also take the saddle off and give it a smack down with a large hammer to try and break the corrosion bond.

Note that the seatpost will be a write off after doing all this!

[Vetus Ossa]

I would say using ammonia is the when all else fails option.

[gaz]

viewtopic.php?t=16716

[nirakaro]

I tried nearly all of those methods (including ammonia), and got nowhere. What finally worked was pouring a hot, strong solution of caustic soda (handle with extreme caution!) into the seat post every day for about a fortnight, which ate enough of the aluminium that it was fairly easy to hacksaw the rest of it out. The frame was due for a respray anyway!

[Biospace]

I don't think enough can be said about the dangers of using strong solutions of caustic soda, a very small splash which catches an eye can mean the end of sight. Full protective gear should be worn, together with a good supply of vinegar or other acidic solution to hand should things go wrong. When a strong solution hits the alloy there is the likelihood there'll be more exothermic activity, meaning the caustic can be propelled back out of the tube.

It's not necesary to use so strong a solution that it reacts excessively vigorously on contact with the alloy, instead a little patience is the best approach in my experience - up to a week before examining the result. In cold weather it will take longer.

If penetrating oil (ATF with a small amount of acetone can work very well, or 50-50 paraffin and oil) doesn't shift things, a bottle of Coke can work surprisingly well, it's well known to free off seized engine pistons.

[Jdsk]

I don't think enough can be said about the dangers of using strong solutions of caustic soda, a very small splash which catches an eye can mean the end of sight. Full protective gear should be worn, together with a good supply of vinegar or other acidic solution to hand should things go wrong. When a strong solution hits the alloy there is the likelihood there'll be more exothermic activity, meaning the caustic can be propelled back out of the tube.

If you get caustic soda or similar on your or anyone else's body I recommend washing it off with large amounts of water for at least 15 minutes, and not using an acidic solution.

"Sodium hydroxide: health effects and incident management"
https://www.gov.uk/government/publicati ... management

Jonathan

[Biospace]

I don't think enough can be said about the dangers of using strong solutions of caustic soda, a very small splash which catches an eye can mean the end of sight. Full protective gear should be worn, together with a good supply of vinegar or other acidic solution to hand should things go wrong. When a strong solution hits the alloy there is the likelihood there'll be more exothermic activity, meaning the caustic can be propelled back out of the tube.

If you get caustic soda or similar on your or anyone else's body I recommend washing it off with large amounts of water for at least 15 minutes, and not using an acidic solution.

"Sodium hydroxide: health effects and incident management"
https://www.gov.uk/government/publicati ... management

Jonathan

What is the reason for not advising using a mild acidic solution on a spill of caustic?

[Jdsk]

I don't think enough can be said about the dangers of using strong solutions of caustic soda, a very small splash which catches an eye can mean the end of sight. Full protective gear should be worn, together with a good supply of vinegar or other acidic solution to hand should things go wrong. When a strong solution hits the alloy there is the likelihood there'll be more exothermic activity, meaning the caustic can be propelled back out of the tube.

If you get caustic soda or similar on your or anyone else's body I recommend washing it off with large amounts of water for at least 15 minutes, and not using an acidic solution.

"Sodium hydroxide: health effects and incident management"
https://www.gov.uk/government/publicati ... management

What is the reason for not advising using a mild acidic solution on a spill of caustic?

My comment above was about bodies. it's similar for inanimate objects but less important.

Water is more available and cheaper. There's no heat of reaction. There's no risk of harmful effects from the acid. It doesn't matter if you apply it for too long.

It's what's recommended by Public Health England (as was).

Jonathan