how would you use it?
If on the ground, you'd have to worry about safety, stability, aerodynamics...
For safety what if you fell off would it keep going? not good if it did.
For stability, how would you stay attached? how would you stay upright?
For aerodynamics, you'd need some sort of wings, including a tail wing.
Then there the size of all this which means it wont look anything like the Back To The Future one.
Have you seen the guy who uses a jetpack to jump off of mountains and glide to the valley?