[AustinH]

This was purely a mental exercise to see if a gear drive could fit in the smallest possible envelope (much like chain in tube, except different). Originally, the thought was that 4" wheels would be the way to go. Unfortunately, that left 0.150" of clearance between the lowest gear and the floor. Depending on the terrain/use case, that may work.

The bottom face of the tube is pocketed almost twice as much as the top plate in order to open up installation options for the gears. Oddly enough, there is constant contact between the hex bearings on either side of the tube owing to the 0.700" diameter boss on the vex gears which contacts the inner races of both opposing hex bearings. No idea how that would work under sudden side loading, but I'd hazard a guess that it's better on the tubing than a completely unsupported sidewall.

How much would a riveted/brazed bellypan help those side tubes?