Ultimate Muni Seat "Mandrill Butt"

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:

  1. Scott Wallis derail base, deathegrip handle, cf bumper, cf brake lever
  2. Faom-closed cell, Remnant from Ebay, $12 enough to do 6 seats
  3. Cover material, $5 remnant for prototype, sheeps leather for final
  4. Thomson seat post
  5. Upholstery thread, nylon webbing, velcro
  6. Electric caerving knife
  7. Band saw
  8. Sewing machine
  9. Sand paper, scissors, sharpie etc.


I started by roughing out foam on band saw, then hit it with carving knife and sandpaper. Top curve is similar to niw KH Freeride(flat).


More shaping then the cover:


Finished cover:


Cover on the seat. And it rides really well, firm but comfy. The Scott Wallis set up makes for better control and is so much lighter. This is just the prototype. Will post pix of final seat.


Do you know what type of foam that was? I have all those tools and parts, just can’t find descent foam anywhere.

The seat looks very nice! Good work! How long did it take you to finish it?

The foam is Minicell closed cell 2lb. Here is a link to the auction I bought it on:
The guys email is: foam4you@hotmail.com

That’s awesome looking! Why didn’t you include an air seat in the process? Also, what is the material of the cover?

I am very interested in this! Do you think it would comfortable with only 1.5 inches for a trials seat that needs low profile? Thanks!

Assuming it’s the kind of foam I am thinking of, it would be comfortable even if it was thin.

I know my DX seat has around 1" of foam on it now, and it’s pretty comfortable.

I think the key to a comfortable seat is making it more flat.

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.

What would be the best foam for 1 to 1.5 inches low profile trials seat? The memory foam I have on now kinda sux: it freezes supper easily and turns rock hard!

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.

My seat would kill you.

Maybe invent a customized type of saddle that is “molded” to your EXACT butt shape! :smiley: Kindof like how they mold orthodics to fit your feet. Hmmmm, that’s a thought.

Do you know of any?

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.

Yes-I’ll measure but mine is no more than 2" thick and I think less. The DeRail base is much deeper than other so gives the illusion of thick foam.

sounds expensive

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!)