I use a Master Lock cable type bike lock only for "Grab and Run" theives. I never leave my locked bike out of sight for more than a minute while in our small post office or country store. Around here bike theives are bottom rung dirt bags without any tools or brains enough to be tricky. On top of that I only ride my grungy cheap looking bikes when I know I'm going to have to lock it up even for a short while.