On Saturday, I was out riding my Coker tired uni. After about 20 minutes, I decided that I wanted to make the air seat a little softer. I get off the uni take the valve cap off and push in the schrader valve. The valve pushes in normally, but air doesn’t come out. I try a small screwdriver and push the valve as far as it would go in. Still no air. The seat is quite firm, so I know that it has air. Until I have a chance to either remove the valve, or take the seat apart to find out what’s happening here, I can only speculate.
Someone filled my air seat with fix a flat.
Someone else (I like a good conspiracy) needing a new 20” tube, took my saddle apart, replaced my tube with their tube then put all the original foam back into the seat. Seems like an awful lot of work, but you never know.
Broken schrader valve.
Some how the tube folded back on itself over the schrader keeping the air from coming out.
Air seats don’t have a lot of pressure at all even when firm. You may have to squeeze the seat to force the air out.
It could also be a blocked or messed up schrader valve core. You can use a valve core tool to remove the valve core. Fiddle with the valve core to make sure the spring is still working and that there is no dirt stuck in it. Then lubricate it with a little bit of spit and put it back in. You can get schrader valve core tools at auto parts stores. You can also get valve caps that have a valve core tool built in (looks like an extended screwdriver slot at the end of the valve cap). The valve core is threaded into the tube stem. You turn it like a screw to remove it.
My first air seat was made with a skinny 16" tube (all I could find that day) that came with fix-a-flat already in it. This seat still works fine, and it’s the most comfortable one I have. I really should have updated it, as it’s on my carbon MUni and it should be kept as light as possible. But I hardly ever ride the cycle and the seat is nice and comfy…
Today I had time to completely remove the schrader valve. Air did not come out of the tube. I then sqeezed the saddle. Again, air did not come out of the tube. Until another day, when I have time to take apart my saddle, and find out what’s keeping the air in, this air seat mystery will continue.