I'm a gun owner and concealed carrier. I will repeat what some have said. I would back away safely if able and let him have the bike. If he then moves to threaten me I would draw with intent to use unless the situation changed real quick. Our conceal instructor said that if you feel in danger enough to draw then you should then fire because if you don't feel the need to fire then you should not have drawn. However, a lot can change in the time between starting a draw and finishing a draw and the person has that amount of time to change the situation. If that happens you have another problem. That person could then go back to their vehicle and get THEIR gun, etc. So.... carrying is a huge responsibility, one that should not be taken lightly. And you need to KNOW what your local laws are and be prepared to work within them, else you will face the consequences.