>>hey dex how do you know you can't run over someone even if you try?

The Segway operates by responding to your body language (at least for forward and back... turning is by a hand grip). You gently lean forward and it goes forward, lean forward more and it goes faster. It doesn't feel like you are leaning though, when you get used to riding it it feels just like walking. You don't think "put one foot forward, lean forward to keep balance, bring other foot forward" when you walk, likewise with the Segway you end up just "thinking forward" or "thinking backward" and it responds, including speed, you have full control over how fast or how slow it moves, down to a creep or a standstill.

It starts to feel kind of like magic but in truth the machine is responding to you shifting your center of balance on the machine to make it move. Specifically when your center of balance moves forward, the machine tips forward, the computer senses the change in angle, and drives the wheels forward in response. You don't actually have to hold the handlebars (although you do to steer) but the handlebars give you a point of reference when you are standing on the machine so you don't just wobble all over the place.

Now if you are standing on the Segway, and you are shifting your balance, you very slightly angle the machine forward and it responds. But if someone is standing on the sidewalk holding the handlebars when you are riding, they can push or pull the handlebars from their position on the sidewalk, and that will make the machine respond as well. You use that when you are teaching someone to ride, while they are getting used to the Segway, you can stand in front and hold the handlebars for them, and you actually have much greater control over the machine than they do. They can lean forward all they want to but if you push back on the handlebars (while standing on the ground) the machine won't tilt and they won't go ANYWHERE. If you pull forward on the handlebars the Segway will move forward.

The Segway has VERY powerful motors. 4 horsepower, that is a LOT. It never feels like it though, as the machine feels very gentle and natural. It needs that strength to keep you upright and balanced under all circumstances, while you are standing still, while you are moving, going up or down hills, whatever. If you need to make a quick stop, even from full speed, you just lean your weight way back off the back of the machine (this takes some practice because your instinct says if you do that you will fall off... but you WON'T the Segway won't let you fall) When you lean back hard all those 4 horsepower goes to stopping you. It is like stopping quickly when you are running. You would lean back and let your sneakers stop your movement while you catch your balance.

Now (here's where I answer your question!) If you are moving forward and you HIT something, the part that is frontmost on the machine while you are moving is the handlebars, because you are leaning forward to make the Segway move. So the part that would "hit" would be the handlebars, and the act of hitting something would push the handlebars back, thereby automatically braking the machine at full force. The friend I took to the training session asked about that and the trainer told him to run into him, going at a good clip. My friend did and hit the guy right in the stomach. The machine stopped and the guy was fine. That was my friend's favorite part of the training

Not to say that someone riding irresponsibly couldn't hurt someone if they tried. You could catch someone's feet or something and probably knock them over. Running over their feet won't hurt because the tires are wide and low pressure so it distributes the weight (I let friends ride over my toes all the time to show them, it is no problem at all). But it is not like a scooter where if the person keeps the throttle open it is going to just plow over everything in its path. Emergency stopping is quicker too because it becomes a "reflex" to lean back just as if you were running and had to stop quickly. But if you see one coming at you and you know the secret you can keep yourself safe under even the worst of circumstances... if someone is trying to plow you down just stay put, reach forward and grab his handlebar as he gets to you and use your weight to push it back. He'll stop and go crying home to mommy. "Curses! Foiled again!"

The photo on the bottom left of my Segway photos page at http://www.idexter.com/click-and-tell/cafe_blue/ shows someone giving the news reporter a ride, the guy in the black pants owns the Segway and is holding the handle bars while the photographer guy (in the gray pants) is getting used to it.