Yes it is illegal. Reason is that the vehicle or cycle is being used in a matter that it was designed for. Example, putting a cycle on 1 wheel when it is designed to be driven on 2 wheels. Or, the officer can also site you for reckless endangerment, reckless driving, improper lane usuage, obstructing traffic, etc. etc. If you were to get the motor vehicle code book from your state on all the rules and regulations you would panic. I could buy a brand new car and be driving off the car dealers lot and get pulled over by an officer and believe it or not he could find something in the motor vehicle code book to give me a ticket for. So be nice and hopefully he will cut you a break – maybe he will have a flash back to when he was younger and some of the stuff he did growing up…..