This has been taken way out of context... Yes, there is slight possibility that an air powered weapon could do damage and even slighter possibility to cause death. But how could you justify returning fire on a moving vehicle, knowing some kid just shot at you with an air gun? If that car is moving away from you on your bike, the threat is gone. End of story.
Since when is it a sight possibility; I daresay, if you are shot with a pellet gun, there will be damage. Also, how am I to know that it is a couple of kids with a pellet pistol? The OP said that that was his experience; that doesn't mean that every nut-job firing out of their window will be a teen, or will be carrying a pellet gun.
If the car slows down, and the person or persons unknown in the vehicle begin firing, then the car (and therefore the danger) isn't moving away from you, is it?
Most people so far in this thread seem to be laboring under the delusion that every single time someone fires something out of their window it will be a pellet gun; many gangs (especially in large urban cities) require members to kill before being accepted, and drive-bys are the preferred method... Like I said, I dont want to argue, but I support the OP in his decision to carry while riding.
If you think you can convince a jury that you felt your life was in peril at the time you pulled the trigger, toward the back of a car that was driving away from you, just because they pelted you in the ass with a bb on the way by.... I'm guessing there are pleny of prosecutors out there who would love to see you try.
I'm sorry, but I believe that the adage "Better to be judged by twelve than carried by six." applies here. When it comes down to it, if I believe my life to be in danger and I believe that someone with a firearm is firing at me, and I have the means to defend myself (a.e. a pistol) then I am going to do so. In a worst case scenario, I'd rather spend 10 years in prison than eternity underground.