I do because they seem to take on personalities of their own, even though I know that's not possible! My Cannondale road bike is "Mike the Bike". He's named after a guy I knew once who was sleek, handsome and just a little bit rough around the edges, like my aluminum framed R6.

My new Surly will be named "La Chatte Noir" - "Cat" for short. I have cat reflective stickers and everything.