Final Flowrider:
The final Flowrider was a great success. The vehicle is a blast to use alone, and fascinating when joined. Each driver is completely free to control their share of the input, both speed and direction. It's up to the two users to work together (or not) to move around and with a little practice you can do some wonderful maneuvers.
The basic layout: Crank the wheels to move around.
Prepare to feel like you're on ice.
The axes of the rollers are perpendicular to the axis of the overall wheel. Thus, you can roll freely from side to side at any instant.
Lateral freedom.
The outer, hexagonal frame is set atop the flowrider frame. Three sets of bearings contain the frame but allow it to freely spin around the user. Industrial strength velcro on the black vertical panels lets two Flowriders join for "coopetive" motion.
Mounting the hexagonal outer frame.
This sequence shows the crux of the Flowrider motion. Notice that the girl can completely change her own direction, while the direction of the unit stays the same. At first both are powering forward and the unit is moving forward and to the right. She rotates her cart and soon is getting a free ride, freely rolling on her rollers while the guy does all the work. If she continues her rotation and starts to rotate her wheels backwards the unit will continue to move in the direction it began in. Note that if the girl starting powering her wheels forward in the second frame, the unit would now move forward and out of the screen. Basically, it's just vector addition, only more fun.
Composite motion.
Why a hexagonal frame? Well, it seemed to work well with the positioning of the body between the cantilevered wheels. Also, the hexagon is "space packing" meaning you could theoretically link as many Flowriders as you wanted.
Fun to drive, and packs space!