A friend of mine owns a company called SNAGG. It specializes in a RFID unit that is about the size of a grain of rice. It is used widely by expensive guitar makers and is imbedded somewhere in the guitar when it is being built for the sole purpose of recovery of the guitar. The RFID (Radio Frequency Identification) unit can be tracked and is quite precise as to location of an item such as a stolen guitar Of course this SNAGG unit won't prevent theft, but has been proven to be quite efficient.
Maybe hide one in valuables such as our expensive antique bicycles.
Mike Cates, CA.