RYNO Motors' single-wheeled electric scooter is self-balancing, has a turning radius of zero when stopped, and only takes up about as much space as a folding bicycle -- so it's conceivable that commuters could bring one onto a train. Plus, it looks like it fell out of a Japanese anime.
However, it only has a maximum range of 20 miles between charges, a top speed that is limited to 12.5 mph (the actual top speed of 25 mph is limited to keep the RYNO scooter within the more relaxed legal boundaries of "personal mobility scooters".
