Another whimsical bike idea - the MonoArc. This attempts to solve the problems with the Monowheel:
1) Heavy due to large rigid wheel
2) Complex construction with 3+ rollers
3) Gerbiling problem
4) Centerline visibility problem
The MonoArc replaces the large wheel with a bunch of small wheels in an arc.
1) Lightweight due to minimal frame and small wheels
2) Simple construction with few moving parts
3) No gerbiling due to very flat arc. It's a shallow arc from a much larger radius.
4) No visibility problem
For propulsion, there is a larger wheel in front. It's fixed, so you lift it for steering (shift your weight rearward to lift it). The wheel is flanked by plastic cones that you engage with rubber friction rods strapped to your calves and heels. You "push" the rod along the friction cone to drive the wheel. Gear ratio varies with the radius of the cone where you engage it.
Due to the limited grip of friction, this system is more for casual riding than speed or power. A more powerful version would use sawtooth rails engaging gear ridges on the drive axle. Either way, this direct drive system minimizes complexity, weight, and transmission losses.
To help you shift your weight, there's a vertical handle between your legs. You push/pull to shift your weight.
Construction is very simple. It's just two plates, held together by the seat and axles. The handle is attached to one plate.
Compared to a normal bicycle, the MonoArc has some potential advantages. It could be lighter due to the minimal frame. It could have lower air resistance. It could be simpler to maintain - no flats. It might be less expensive. It might carry and store more conveniently, hanging on a wall.