Tiliqua

Hey all,

I have for the last few months been riding a 70-80's built(according to a bike friend who looked at it) thin chromoly steel frame roadbike that I basically got from a friend. Bicycle works well enough-however it was left out in the rain for long enough to rust the chain which we cleaned-but also to rust the seatpost solidly into the frame. I've tried spraying rust remover along the edges and hoping it would seep in and then attempting to twist the seatpost out but to no avail. It is a minor problem but I'd love to have the seat just a few inches higher-currently it is a little low for me. I've been riding it daily and have done several 15-20 mile runs but it would not be comfortable for longer rides.

I'm also curious if over time the rust will eventually corrode the frame from inside out? I'd assume that would be probably further down the road than the rest of the bike will last.

Advice greatly appreciated for a poor college student!

mechBgon

One time-consuming option is to use a jab hacksaw to slice the post into segments down its inside wall. Some interior frame damage is inevitable, but it gets the job done.

wrk101

Search is your friend. Stuck seat post is a common problem.

Pir0

What materials the seat post made out of? If it's alloy you could melt it out with Caustic Soda.

Other ways I've got seatposts out is with heat (damages paint) and by dirlling a hole through the centre and passing through a thin steel bar of some sort (i used threaded bar picked up from a DIY shop) and twisted it for better leverage.

fietsbob

+1, been thru this repeatedly,On several lists. read search results..
next time, pull the seatpost as a part of regular maintenance.
A thin wipe of grease will do.

tadawdy

Had the same problem on a bike I bought. All mine took was to apply some 3-in-1 (all I had at the time) and let it sit over night. Then I used the seat as leverage and popped it right out. Depends how badly it's stuck, but steel-on-steel is a pretty easy one to budge.

GeoLes

Re regreasing a seat post. It is not advised that you apply lubricant to carbon fibre. How do I prevent seizure of carbon post on carbon frame? (Yes, there is an aluminum sleeeve in the tube?

mechBgon

You can use carbon assembly compound, which is something like grease but with grit particles added.

fietsbob

There is a galvanic corrosion possible with 7000 series aluminum
and a carbon fiber seat post

because 7005 and 7075, etc , contain Zinc.. C + Zn = a battery.

that would be exceedingly rare.. perhaps the sleeve is 6000 series,
that would not have Zn in the alloy..

Most people who post about stuck seat posts ..
they have gotten a CL or yard sale /police auction
bike with an aluminum post in a steel frame.

Myosmith

Plan A: If your seattube has holes for a drink holder, you can place the bike upside down and fog a generous amount of penetrating oil into the holes and leave the bike inverted overnight. Flip the bike over in the AM and put a piece of wood or something protective over the top end of the seat post and then give it a sharp rap with a hammer. Don't get carried away as you are not trying to drive the seatpost into the frame, just disrupt the rust bond enough that you can start turning and pulling the post out. If you don't value the post, a pipe wrench can be useful, but will seriously mar the finish.

Plan B: Slowly and gently heat the seat post, not the frame until it is too hot to handle comfortably. Feathering the flame from a propane torch over the post works well. Keep working the seat post back and forth both during heating and as it begins to cool. Usually there is a point as the post cools that it will pop right out. This works especially well when you have an aluminum post in a steel frame as the aluminum cools more quickly, shrinking away from the steel tube slightly. I've also done this with steel posts in a steel frame without discoloring or destroying the paint on the frame.

Note that these have only been tried on steel frames with steel or aluminum posts.

hybridbkrdr

I second the idea of letting 3-in-1 oil soak in. But, it may take more than a day like the previous poster stated, maybe a week. And you may have to tap the seat to get it to move a little.

But, I'm casually wondering whether using a pair of vise-grips to crush the seatpost just above the frame would be worth it. Because even if you destroy it to get out of there, my knees might hurt if my seat is too low. I think your knees are too important not to fix that.