Bicycles are easy targets for thieves.  Be sure to lock your bicycle to a secure object at all times utilizing a good quality bike lock and chain or cable.  Make sure to run the chain/cable through both the wheels and the frame as well as the fixed object.

Make certain that your bicycle is registered with the City of Pleasanton for easier identification in the event your bicycle is found.  It is best to etch some sort of identifying mark (initials) on your bicycle, adhere a City of Pleasanton identification number on your bicycle frame, or etch an owner applied number into the frame as those numbers are easier to trace back to you and to return a stolen/found bicycle to its owner. 

Keep a record of the original make/model/color/serial number to the bike as that is the best information to have in the event your bicycle is stolen.