How to modify your Velo Uni (or similar) seat

I modified my Uni seats for a couple reasons... To lighten it... I removed the seatpost and shaved a good deal of plastic off from the underside of the seat. To give myself more standover room... Removing the seatpost and shaving plastic from the underside of the seat lets you push the seat really far into the seat-tube of your bike (Brisa seat-tubes are 26.8, and the plastic post of the seat fits perfectly). For safety... The uni seats are really hard and I would imagine would be painful to land on. By removing almost all of the support on the bottom side of the seat, I made it pretty flexy, so it should flex a lot if I should hit it... (I probably went a bit too far... I'll probably break the seat if I land on it, but it's unlikely I ever will)

Top row: Before pictures, Bottom row: After pictures

All you need is some kind of grinder. I used my 4 1/2" Disc Grinder, which I use primarily for grinding my rims. I suggest leaving your seat on your bike, as high as possible. I ground off the sides of the seat first (the smooth surface... see picture below).

After grinding the side off (roughly, don't worry about making it perfect yet), begin to grind away at the plastic below the seat top and tear off the bottom edge of the seat... Very carefully grind away at the underside of the seat... The more support you take out, the flexier the seat will get. I even ground a little of the seat top itself on the underside, which made it nice and flexy. To remove the seat post, either pull out a drill and drill out the little pin holding the seat to the post, or use your disc grinder (this will remove a bit of plastic, however) to get rid of the pin... After drilling/grinding away at the pin a bit, try to twist and pull the seatpost out. Once you get the seatpost out, you'll want to grind away as much plastic support near the plastic post as possible, so the plastic post can go as far into the seat tube on your bike as possible (for the most clearance). This would be best done with a dremmel, but can be done with a disc grinder (which I did). Keep going until you like the way it looks/feels.

Finished product


Seat on my B26

Seat on my B20