can't get my stuck aluminum seatpost out of my steel frame, I'm sure this has happened to others before? how do I get it out without hurting the frame?

Clamp the the seatpost in a vice and carefully twist the frame.

Standard reference for stuck seatpost removal:

http://www.sheldonbrown.com/stuck-seatposts.html

How long has the post been in the frame without being moved?

If it's not years, you may be able to use Coke to free it.

I have seen many posts shifted by a seat tube of coke left overnight upside down. Turn the bike over with the BB out. Pour regular Coke in tube, put the post head in a plastic bucket or similar. Leave over night and in the morning the coke may have broken the join between post and frame enough to let you twist it out.

Only works on alloy post in a steel frame as the alloy is affected by Coke more than the steel.

Good luck

Try "PB Blaster" supper funney looking can but its the best penitrating oil I know of, its avil in hardware and auto stores. Soak it from the B&B hole or a water bottle screw hole with the frame up-side down.

I'm not downing the "coke" thing but be sure to clean up well if you try it, coke eats steel, over time, (one 8 penney nail will be gone in one week in a bottle of coke).

All the best -- Bill

I had the same thing happen, steel frame aluminum seatpost. The LBS tried for two days to get the post out and couldn't. I bought them some ammonia had them pour it in left it for a few hours and out it came.

now I got to try these one at a time. penetrating oil did not work..." Sheldon" had some great help, the ammonia I will try first, then the Coke in the tube method sounds very interesting and I will try that next, as a last resort I guess the hacksaw blade ...thanks everybody,I will let you all know the results....

then a little heat with a hairdryer and out it came by twisting the seat.it was really corroded along with rust from the frame..

Thanks for getting back with us on this, and good to hear you got the post out.

The Sheldon piece has a bit of a history. The quote at the end of the article used to be the article's title, unattributed, a number of years ago. Sheldon took some flak for that and removed the quote altogether. Now it's back - at the bottom and attributed.

Sorry to reviving an old post, but I am experiencing the same problem and would like to know where can I buy ammonia. A brand or product name would be helpful.

Also, there is a way around having to remove the whole BB to inject ammonia into the tube, or there is no way around it?

Thank you.

seatpost if you are patient and work at it..ammonia (liquid is a housecleaning item,I bought mine (a quart the smallest size they had) at Walmart. I left the seat on the seatpost to have something to hold onto to try to twist loose the seatpost anyway I could get it to move, I turned the bike upside down and taped tightly the area around the seatpost opening, then I poured the ammonia throught the waterbottle thread holes using a funnel made of tape.
poured enough ammonia until it was backing out the threaded holes and kept ammonia topped off for at least 30 minutes so it could dissolve the rust..then turned bike back up and tried to twist the seat post loose by holding onto the seat and twisting it, and it did wiggle loose a fraction, at that point I then removed the tape and flooded the area with wd40 down into the seatpost clamp and kept twisting the seat and seatpost and voila the seatpost came loose!! you may have to repeat the ammonia soaking two 0r three times, I guess if the seatpost won't work loose try tapping the seatpost with a block of wood and hammer (after removing the seat) anything to get movement between the seatpost and the tube. if that doesn't work go have a beer or cup of coffee and go at it the next day with destructive measures such as a pipewrench,vicegrips,channellock pliers but let it soak overnight with wd40 first.. good luck.....Oldbikes

Thank you Oldbikes! I totally overlooked the obvious point of injecting the ammonia into the tube (THRU THE WATERBOTTLE CAGE HOLE).

So you can buy pure ammonia? I didn't know you can purchase pure ammonia and thought I had to purchase cleaning product which has partial ammonia to do this. If you have a brand of the product you purchased, please let me know.

I will be purchasing an old bike from a friend and he told me the seatpost is stuck. He told me to take it to a bike shop to have it taken out. But I will try the ammonia trick first.

thanks!

did get the tube area hot with a hairdryer just before it came loose..good luck..

So you can buy pure ammonia? I didn't know you can purchase pure ammonia and thought I had to purchase cleaning product which has partial ammonia to do this. If you have a brand of the product you purchased, please let me know.

Pure ammonia is a gas, and you can purchase cylinders of it from a chemical supply house. You would need a matching ammonia regulator as well. Alternatively, farmers use it for fertilizer and you see 500 gallon pigs of it being carted around the fields. However, what you actually want is aqueous ammonia, which is available in the household cleaners section of your local supermarket or hardware store. :)

then a little heat with a hairdryer and out it came by twisting the seat.it was really corroded along with rust from the frame..

I hope this was just an excersise to seperate the two, as I am not sure if it is a good idea to salvage the frame or the seatpost with a rusty seat tube.