My daughter (11 years old today!) has PDD-NOS, an autism-spectrum disorder. I've been trying for years to help her ride a bike, but she was only successful with training wheels. Aside from having very little concept of safety, she also has exceedingly poor balance. We tried a few different types of scooters, including a four-wheeler, but she disliked them so much that she would end up pushing or carrying them instead of riding. She gets frustrated easily, which makes it difficult to help her learn new things, like riding/scooting. I've been considering a tandem, since she's too big for a trail-a-bike now. Anything to get her out from in front of the TV/computer would be a blessing!
As for the autie/aspie thing, I never heard the terms til I read this thread. My first impression was that they sounded a bit offensive, but if people with these disorders find them acceptable, then they're fine by me. I've often heard a group of autistic children referred to as "the autistics", which I feel is okay. Realistically, there are many other far more offensive terms that you hear from time to time, mainly from non-autistic children that don't understand as well as an adult (*******, dopes, idiots, and the like).
My daughter is definitely different, but she has friends, hobbies, likes and dislikes, etc, like any other kid. Having never been exposed to this kind of situation prior to my daughter being born, I have to say that every day is an adventure, to say the least. However, my kid doesn't feel that she is disabled, so my wife and I try our best to not treat her as such. We guide her in the best way we know how, praise her when she succeeds, and console her when she fails. We don't know what the future will hold, obviously, but I try to stay optimistic.