No, I use two: One Onguard Bulldog Mini+Krypto Combo Cable Lock=Alone, either lock is inadequete protection for my entire bike. Together, a theif must have two types of tools to steal my entire bike.
If I was in the unfortunate situation where I was forced to lock my bike outside in Boston overnight (my college dorm has indoor racks) I would definitely use a third lock though. Bikes locked overnight in large cities like Boston have an uncanny tendency to grow legs. Especially if you lock it up in the same place every day overnight, no matter how tough a lock you think you have.
-Lock either wheel to my frame with U-lock then use cable lock to lock other wheel and frame to pole or bike rack.
-lock rear wheel through triangle a la Sheldon Brown
to pole/rack then lock front wheel to frame using cable lock.
And I always take my quick release seat with me.
Last edited by thehum; 10-21-08 at 10:58 AM.