Stuck seatpost

[JamesM]

the ammonia will eat the alu seat post so what will it do with an alu frame?

I believe ammonia only eats the aluminium oxide but doesn't harm the aluminium itself. It's therefore safe to use on aluminium posts stuck in aluminium frames.

Caustic soda on the other hand disolves aluminium so is good if you want to remove an aluminium post from a steel frame and you aren't bothered about saving the post.

 

[bm0p700f]

The problem with ammonia is you have to be in a very well ventilated room. Also I have no idea if the household strength solutions (9.5%) are stong enough. Not to sure how commonly it is stocked either. Ammonia will not seriously damage aluminium, it does react with it releasing hydrogen. The reaction so slow that it will not do much if any damage.

Aluminium oxide does react with ammonia solution as it reacts with the hydrogen ions in the solution but it has to penetrate. Ammonia solition is mostly water so i am not sure it will penetrate.

I would not bother with casutic soda as it a little dangerous - it is caustic and it will harm the frame.

If mechanical methods don't work then try the ammonia as a last resort but I will be surprised if it works as you only need a little bonding to prevent the seat post moving.

 

[bhill22]

Be patient
I took 3 weeks of constant spraying anti seizure between post and frame, eventually with a little force and constant twisting and re application of spray the post came out, i could not believe the amount of heat generated from the twisting
then there was a lot of work to clean, clean, polish polish the tube and post and both have been reused and silky smooth after a re grease

good luck

 

[My_Teenage_Self]

Please don't laugh, but coke may help you.

It'll take a while, but it will dissolve the aluminium oxide. Keep applying it, or, better yet, take your BB out, turn your frame upsidedown, and fill up your seat tube with it. Leave it to soak for a few days, then start wiggling.

If I hadn't had it work, I wouldn't believe it either.

 

[legrandefromage]

you could always try: