This is my first attempt at a custom Muni seat. I started with a Scott Wallis DeRail base, handle and bumper. If you have never seen these, they are works of art, strong, light and well thought out. First photo shows all the bits I started with:
Scott Wallis derail base, deathegrip handle, cf bumper, cf brake lever
Faom-closed cell, Remnant from Ebay, $12 enough to do 6 seats
Cover material, $5 remnant for prototype, sheeps leather for final
The problem I’ve had with “closed cell” foam, is that it becomes pretty hard once it’s compressed from your weight, and thus becomes permanently thinner. This foam is quite dense to begin with, and it does not “bounce” back very quicky and stays compacted. But I think Jim’s setup should work well because his foam looks to be pretty thick so hopefully there will be sufficient cushioning. I also would probably try adding an air seat feature under the foam for added comfort and adjustability.
Yep, memory foam is even worse for that very reason-it has almost zero-bouce back response. I suppose if you rode in super slo motion, you would be able to wait for the foam to “puff” back up. I think the standard medium density foam works best. It retains its shape, bouces back quickly and will not generally become hard from permanent compression. Just make sure it’s not too thin to prevent bottoming out on your seat base. Actually, I would get the densest foam I could find that still bouces back fast, but would allow a nice center channel to be cut down the middle and still maintain firmness.
This seat is very comfy, much lighter and tighter(doesn’t move around like an airseat). Also, totally reliable, zero leaks! The foam is the kind they use on gym floors and will not compress over time. The cover is temporary for the pattern, just cheap vinyl. I have leather to sew up now.
Make a batch of plaster, thick viscosity, sit in it, leaving your “impression”, wait for it to dry. Then fill it with some sort of rubbery material that will harden frim. Remove from mold, trim off excess, and “Viola”…your very own custom seat foam! (I have a feeling it would be waaay to wide!)