Philosophically speaking:

"You see things vacationing on a motorcycle in a way that is completely different from any other.  In a car you're always in a compartment, and because you're used to it you don't realize that through that car window everything you see is just more TV.  You're a passive observer and it is all moving by you boringly in a frame.

On a cycle the frame is gone.  You're completely in contact with it all.  You're in the scene, not just watching it anymore, and the sense of presence is overwhelming.  That concrete whizzing by five inches below your foot is the real thing, the same stuff you walk on, it's right there, so blurred you can't focus on it, yet you can put your foot down and touch it anytime, and the whole thing, the whole experience, is never removed from immediate consciousness."

Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values
by Robert M. Pirsig