Jeff Wisnia wrote:

"How Things Work" has a video and some pretty detailed text about what's
inside the Segways. He

http://videos.howstuffworks.com/segway-mini-video.htm

Jeff (Who still regards the Segway as the answer to the question nobody
asked...)

Other than being a bit nifty from a technology perspective, the only
benefit I see to a Segway is that it's a bit more practical to take on
public transit than a conventional bicycle.