If I feel really worried about my bike I use both an alkatraz(?) chain lock (I got it for about $15 from some shop in coral springs, florida it's just a little smaller than the kryptonite new york chain) and a kryptonite evo U-lock. I feel ok with that set-up because I think you need different tools for a chain and a U-lock, but then again I step outside about ever 15-20 minutes to check on it.