A question that I receive often through my column on this site is how one should remove a seatpost that is stuck in a frame. Rather than answer each one, I can simply reprint the section from Chapter 10 of “Zinn and the Art of Mountain Bike Maintenance” that touches on that very subject.
Removing a seatpost that has frustrated all normal methods of removing it is a difficult job requiring lots of attention and skill because of the risk involved. This may be a job best done by a shop, because if you make a mistake you run the risk of destroying your frame. If you’re not 100 percent confident in your abilities, go to someone who is — or at least to someone who will be responsible if they screw it up.
1. Remove the seat binder bolt. Sounds easy enough.
2. Squirt penetrating oil around the seatpost, and let it sit overnight. To get the most penetration, remove the bottom bracket (Chapter8), turn the bike upside down, squirt the penetrating oil in from the bottom of the seat tube, and let it sit overnight. In the absence of penetrating oil, Coca-Cola poured inside can sometimes work well for breaking free rusted parts.
3. The next day, stand over the bike and twist the saddle.
4. If Step 3 does not free the seatpost, you will need to move into the difficult and risky part of this procedure. You will now sacrifice the seatpost. Remove the saddle and all of the clamps from the top of the seatpost. With the bike upside down, clamp the top of the seatpost into a large bench vise that is bolted to a very secure workbench.
Congratulations, you have just ruined your seatpost. Don’t ever ride it again.
Grab the frame at both ends, and begin to carefully apply a twisting pressure. Be aware that you can easily apply enough force to bend or crackyour frame, so be careful.
If the seatpost finally releases, it often makes such a large “pop” that you will think that you have broken many things!
5. If step 4 does not work, you need to go to a machine shop and get the post reamed out of the seat tube. If you still insist on getting it out yourself, you should really sit down and think about it for a while. Will the guy at the machine shop really charge you so much money that it is now worth the risk of completely trashing your frame? Have you thought about it for a while? And still you insist on doing this yourself? Okay, but don’t say I didn’t warn you.
Take a hacksaw and cut your seatpost off a little more than an inch above the seat lug on your frame. (Now you really have destroyed your seatpost,so I don’t have to warn about riding it again.) Remove the blade from the saw and wrap a piece of tape around one end. Hold on to the taped end and slip the other end into the center of the post. Carefully (no, make that very carefully) make two outward cuts about 60 degrees apart.
Your goal is to remove a pie-shaped wedge from the hunk of seatpost stuck in your frame. Be careful, this is where many people cut too far and go right through the seatpost into the frame. Of course, you wouldn’t do that, now would you? Once you’ve made the cut, pry or pull this piece out with a large screwdriver or a pair of pliers. Be careful here, too. A lot of over-enthusiastic home mechanics have damaged their frames by prying too hard here. But you wouldn’t do that, would you?
Once the wedge is out, work the remaining piece out by curling in the edges with the pliers to free more and more of it from the seatpost walls. It should eventually work its way out. Now, once your seatpost is out of the frame, remember to follow the suggested regular maintenance procedures required for a seatpost. In otherwords, take it out and apply grease every once in a while. You don’t want to have to do this again, do you?
VeloNews technical writer Lennard Zinn is a frame builder, a former U.S. national team rider and author of several books including the pair of successful maintenance guides “Zinn & the Art of Mountain Bike Maintenance” and “Zinn & the Art of Road Bike Maintenance,” and “Zinn & the Art of Triathalon Bikes.” Readers can send brief technical questions directly to Zinn.