Maybe not. Have you ever uploaded any workouts to an online log? I upload all my stuff to RunningAHEAD.com (uses the Garmin Communicator plug-in). When I do so the uploader logs the serial # on my Garmin every time. Perhaps there is some way that Garmin can recognize where your Garmin is if the thief turns it on. I've heard of stolen cars being recovered when there is a GPS-enabled cell-phone within the car. If you know the serial # of your Garmin unit it doesn't seem to me all that impossible that your bike could be tracked-down with that info.

