I have heard many people complaining about the slow return of the Maverick SpeedBall and the Crank Brothers Joplin Seat posts. The recommended remedy for this is to run the seat post with the seal head loose. There is one problem with this. If it is loose enough for the air to enter the post when raising it is loose enough to pull in contaminates with the air.
My experience with the post is not that air is being trapped in the post preventing it from raising as Maverick states. It is that air cannot get back in. The design of the post is such that when compressed the shaft displaces air in the seat tube, forcing it out through the seal. Due to the design of the seal, when you attempt to raise the saddle the vacuum created forces the seal to seal tighter preventing air from gaining access to the seat tube. This is a theory I have tested with a bit of soapy water. This is also the reason we all suffer poor performance after a particularly wet ride.
My cure for this is a simple one. Many of you may remember the old ZYZYX forks built by Hanabrink many years ago, they suffered from a similar problem, and this is where I borrowed my idea from.
First you must start by removing the upper part of the post ( stantion ) from the lower post ( seat tube ). To do so is very simple; first you need to unscrew the seal head from the seat tube making sure that is is fully removed. Second using a ten mm socket on the end of a short extension unscrew the nut on the bottom of the post. This will allow you to remove the stantion from the seat tube.
Next is the actual fix; Start by thourghouly cleaning the seat tube. Next will require a long 1/16 in drill bit. In the bottom of the seat tube you will notice a silver base plate that the stantion was secured to earlier. You will be drilling a 1/16" hole in this base plate. You will want to drill this hole halfway between the wall of the post and the hole in the middle that the stantion secures to.
Now this cure is best for those of you that ride a bike with out an interupted seat tube. Those of you that do run a greater risk of sucking contamants into the system through this hole. If you do have an interupted seat tube you can reduce that risk by securing a piece of sponge in the bottom of the post to act as a filter preventing contamants from entering the bottom of the post.
Reasembly; is the opposite of dissasembly. Make sure all parts are thoroughly cleaned and lubbed with a light petroleam based grease.
This modification allows air to escape and enter the seatpost through this small hole in the bottom. Maverick no Crank Brothers allowed for air movement within the system.
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Thread: Joplin / Speedball Fixes