Alternate seat mounting methods?

[Coffee Freak Designs]

I have a Rockhopper that I bought in the early 90's. The seat post was stuck in the seat tube, but fortunately, it was set pretty darn close to perfect for me. Fast forward to today when I'd like to strip down and paint the frame and I can't get the aluminum seat post out of the ChromeMoly frame. Pipe wrench crushed and twisted the seat post and prying the ears at the top of the tube split the tube a bit. There is still approximately 6" of seat post still stuck in the tube that I can't get to without completely ruining the tube. About the only thing I haven't tried is the caustic soda trick mainly because of my kids and pets around.

I don't have a tig welder, so I'm thinking that cutting out the seat tube and replacing is not a good idea. I do have a flux core welder, but I've heard ChromeMoly will get brittle if you flux core weld it.

The other option would be to cut off the top of the tube and cap it off and mount the seat some how to the crossbar. The saddle I have is a bike store saddle with the two parallel bars.

Pictures of how you did yours or suggestions would be awesome.

 

[us56456712]

I have a Rockhopper that I bought in the early 90's. The seat post was stuck in the seat tube, but fortunately, it was set pretty darn close to perfect for me. Fast forward to today when I'd like to strip down and paint the frame and I can't get the aluminum seat post out of the ChromeMoly frame. Pipe wrench crushed and twisted the seat post and prying the ears at the top of the tube split the tube a bit. There is still approximately 6" of seat post still stuck in the tube that I can't get to without completely ruining the tube. About the only thing I haven't tried is the caustic soda trick mainly because of my kids and pets around.

I don't have a tig welder, so I'm thinking that cutting out the seat tube and replacing is not a good idea. I do have a flux core welder, but I've heard ChromeMoly will get brittle if you flux core weld it.

The other option would be to cut off the top of the tube and cap it off and mount the seat some how to the crossbar. The saddle I have is a bike store saddle with the two parallel bars.

Pictures of how you did yours or suggestions would be awesome.

I have drilled them out with a heavy duty hammer drill. Use a smaller size drill as the hammering distorts and makes the hole bigger. Then take a hack saw blade wrapped in duct tape for a handle and saw a kerf in the alloy down to the crmo. The remainder of the tube will come out. If it is not wrinkled and has a large enough opening for the hack saw blade, forget the drilling and go right o sawing.

 

[roadwarrior]

Here is my idea. (A.) Long bolt to catch edge bend at top, tap away. OR (B.) Slide hammer with long bolt or other object to catch edge of seat tube. I would throw some PB Blaster down the tube as well. Let it go down the tube past the post then turn it over so it will run back up.

 

[LukeTheJoker]

Here is my idea...

I like it! The extra wall thickness of the aluminium post should help with grabbing the edge of the bolt head too...

Luke.

 

[Coffee Freak Designs]

I may give that a try. I'll have to see if the bottom of the seat tube is capped to get the nut into the bottom.

 

[roadwarrior]

I may give that a try. I'll have to see if the bottom of the seat tube is capped to get the nut into the bottom.

Slide it down from the top, catch the edge, then slam it up.

 

[RustySprockets]

You're going to need at least one extra set of hands to hold the frame firmly while you work your magic with the slide. Lube liberally. In a perfect world, you'd have some sort of expanding anchor that snaps open once slide passes the bottom of the tube.

 

[deven_science]

I wish I was home now, I'd take a pic of one of my stranger fixes for this problem. I cut the stuck seat post a couple of inches above the seat clamp. Then I cut a seam in the back down about an inch or so. Then I put a seat clamp on THAT, making the old seat post the new seat tube, and slid in a smaller seat post, and tightened it down. I has two seat post clamps, one right above the other, but hey, it worked great.

 

[horsefarmer]

Got this 80's Raleigh bike with super stuck aluminum seat post. Frame is kinda tall for me so I cut the stem off short and drilled a 3/4" hole thru it.

An old one piece crank is used as a set back seat post.

Cut a slot with a hacksaw blade so existing frame clamp can secure new seat post.

 

[SSG]

The hack saw blade trick is slow but it works (its easier on an aluminum post than a steel one though).

 

[horsefarmer]

I have it pretty much ready to go now if we get a warm day i will get it out for a test ride!

 

[HOOSIERCYCLES]

I used liquid Drano on one frame let it sit for couple of weeks, it did loosen tried on another did not work.
remove crank/BB plug any holes at seat post end fill seat tube let it sit as long as possible.

 

[LukeTheJoker]

In a perfect world, you'd have some sort of expanding anchor that snaps open once slide passes the bottom of the tube.

Sort of like a hydraulic lifter remover tool? Cool thinking!