I do not pack weapons or even keep them in my home, and belive most who do are packing a false sense of security. I use my wits, and try to maintain situational awareness. It isn't a perfect system and I may still wind up on the loosing end. This would be no different if I had a fire arm, or even pepper spray.

Also keep in mind that you can often take that bike where he cannot take his car, and the odds are overwelming in your favor that you will be able to outrun him if he has to dismount.