The seatpost is stuck in my Giant TCR Composite and it won’t budge. I’ve tried lubricants to loosen it up, but nothing has worked. It won’t twist side-to-side or up-and-down.
I hope it hasn’t seized into place, gotten stuck due to crud in the seat tube or something.
Do not try to remove a seatpost by pulling on it with a pipe wrench, locking pliers or any other tool. Instead, use a saddle. Nothing gets as good a grip on a seatpost as a saddle, because it has the hardware designed specifically for the purpose. If you are worried about damaging the customer’s saddle, use one of the yellow BMX saddles you have in the cellar that will never sell anyway.
At the first sign of difficulty in moving a seatpost, remove the seatpost bolt completely, don’t just loosen it. Sometimes this is all that it will take.
The next thing to try is prying the ears of seat lug apart slightly with a screwdriver. Sometimes it is easiest to stick a flat-bladed screwdriver between the ears and twist gently. Other times you may have better luck by inserting a large Phillips head screwdriver or Allen wrench into the bolt hole on one ear at a time and bending the two sides individually.
Most repairs are easier if the bike is held in a work stand, and for some jobs it is helpful to have the bike partially disassembled. This is not the case with seatpost extraction.
It is easiest to work with a fully assembled bike, sitting on the floor on its own tires. When pulling on the seatpost, the best way to hold the bike down is to put a foot on a pedal.
You can get the best purchase by standing behind the saddle, with your legs straddling the rear wheel. It may be helpful to have an assistant hold the front end of the bike steady. Even if you don’t use an assistant, the front wheel should be restrained from turning from side-to-side. This may be done with a commercial handlebar clamping tool, or by strapping the wheel against the down tube with a toe strap.
For the most recalcitrant cases, if the seatpost has a one-piece saddle clamp, you can mount the top of the seatpost in a vise, then twist and pull the bike or frame. If you have an assistant handy, have one of you apply the force in a rotational direction, while the other applies force to pull the frame away from the seatpost.
Unfortunately, many seatposts will not lend themselves to this approach, because the saddle clamp may be pressed or bonded to the tubular part of the seatpost, and the joint isn’t designed to withstand such force.
Normally, it is best to raise and lower seatposts straight up or down, without twisting them, because twisting can cause unsightly scratches on the seatpost. This does not apply when you are dealing with badly stuck post, however. With stuck seatposts, your first priority should be to try to turn the seatpost, even if it won’t move vertically. You can apply much more effective force rotationally than you can vertically, and if you can get the post to turn, victory is in sight. Once you can turn the seatpost, you can run oil in between it and the seat tube, and the twisting action will distribute the oil, completely freeing the post.
For steel seatposts stuck into steel frames, where the problem is often caused by rust, penetrating oil can do wonders. If you don’t have real penetrating oil, any light lubricating oil is better than nothing, but penetrating oil is made specifically for this purpose, and you should buy a can if you don’t already have one.
Aluminum seatposts frequently become stuck by corrosion also, and penetrating oil is almost useless against aluminum oxide. Fortunately, aluminum oxide can be dissolved like magic by using ammonia.
If nothing else works to free up a steel or titanium seatpost, the next-to-last resort is to heat the seat tube up with a hair dryer or propane torch. This should be done with great care so as not to do too much damage to the paint. You should work as fast as you safely can, because you want to heat the seat tube so that it will expand, but if possible you should quickly put the torch down and start pulling on the saddle before the heat works its way through the seat tube and makes the seatpost expand too.
The torch technique is worse than useless when you are dealing with an aluminum seatpost stuck in a steel or titanium frame, because aluminum expands twice as much as steel, and 2 1/2 times as much as titanium for the same increase in temperature. In fact, the exact opposite technique will often do the trick for aluminum seatposts–cool the seatpost down as rapidly as possible. The contents of a CO2 tire inflation cartridge applied inside the seatpost can shrink it down just enough to do the trick.
If nothing else works, the final resort is the old hacksaw blade trick. Cut the seatpost off so that about 1/2" is left sticking out, then insert a hacksaw blade into the seatpost and carefully cut a slit in the post. This is very laborious, and you run the risk of damaging the frame if you cut too far, but this approach cannot fail. Once you have cut the slit, grab one edge of the cut with a locking plier and roll the seatpost up inside itself and pull it out.
And more importantly is it composite or alloy? If it is a composite seat tube then I am unsure what the problem is but if this is an alloy seatpost, you may find that sweat/water has migrated into the tube and caused an electro-chemical reaction resulting in the current state of affairs. I like to be optimistic, but a friend had a similar problem with his Trek 5500 - he is a jeweler by profession and had to resort to using some specialized jewelers cutting tools to cut the seat post in slices out of the seat tube as a week of various solvents did nothing to weaken the bond between frame and seat post.
I’ve tried the lubrication, twisting, using a buddy for help to hold it steady trick and am out of ideas. I’ve even borrowed a crescent wrench to whack the side of the seat to try and twist it while a buddy held it still.
The sucker still won’t budge. I’m very hesitant to try much since it is a carbon frame.
Take the seat off and put the seat post in a vise so that the bike is upside down. Using the extra leverage of the bike might help break the bond/rust that’s in there. Don’t twist/pull on it for too long at a time.
Cut the seat post down a bit so that there are a few inches sticking out of the seat tube. What you do next is to try to cut a couple channels on the interior of the seat post to create some room and hopefully help loosen it. Use a jab saw (holds a hacksaw blade at one end) for this task. Squeeze the remaining pieces together with a vise and you should be able to remove the seat post.
Try #1 before #2. In fact, try #1 a few times before #2. If you haven’t tried it, use a screw driver to spread the compression slot a little bit wider to allow the liquid wrench down (or whatever you’re using) into the seat tube.
A good reminder to take the seat post out periodically and clean it.
