Yes, I am a cyclist. No, I do not belong to a club (but I wouldn't mind it, if I didn't have to do so much laundry on saturdays to wash all my sweaty garments). And like Chris L., I only have one (operational) bike. But what makes me a cyclist?
I think it could be any one of the following things:
1) I ride a bike (of course).
(the rest of these reasons are optional)
2) I sometimes look up to the upper left-hand corner of my glasses while I'm walking, to check behind me.
3) I have cheered weary shoppers at the Kroger supermarket with a bright, blinking red light attached to my person.
4) I am sometimes late to work, my only REAL excuse being I wanted to cycle in.
5) I have felt the joy of giving joggers a near fatal heart attack.
6) I now do not automatically speak kindly to dogs.
7) I consider everyone else who cycles a potential friend.
I know that there are probably 1,001 ways to identify a cyclist from the crowd. These are only a few off the top of my head.