Nice design!
I have to agree with Mr Lim that my favourite feature is the 1" ground clearance. Last year I think you were driving a hovercraft
I wouldn't worry about all of the comments about your choice of speed. It may well be that 16 ft/s is too fast for a single speed, but the way you have set up the gearbox makes it very easy to change the ratio. Just swap out the sprockets in the gearbox, shorten the chain, and away you go. Actually, this is a very good reason not to design with the gearbox directly driving the middle wheel.
Unless we get ourselves a sheet metal sponsor, feel free not to share the CAD with our guys. As pretty as your design is, 610 can't build that way.