Some designs are so fundamentally perfect, that there's little point in trying to improve them. The wheel probably sits right at the top of that list, to the point where the expression 'reinventing the wheel' is used to describe this type of attempt at improving perfection.
That's not enough to deter a dedicated group of Yale mechanical engineering students, who figured it might be fun to build a bike with a spokeless rear wheel. As you can see, the rear hub is held in place four rollers at the top, along with the drive cog which meshes with a planetary gear on the rim. The front wheel is a conventional spoked model, but the students say that was simply due to time and budget constraints.
When asked why they did it, the first answer was that 'it looks cool'. Fair enough, but that's hardly the type of answer that will get you an A in engineering class. Pressed further, they suggested that the space inside the hub could house an electric motor, or some type of storage basket. Of course we've already seen a similar concept that puts the rider inside the hub.
I hope the students all passed the course, although I'm not expecting to see their hubless wheel showing up at the bike store anytime soon.