An abandoned bike sitting in the front yard, or in front of a local restaurant, unsecured, can be an invitation for someone to steal it. Bikes are easy to steal, as they are lightweight, do not make much noise when moved, and most people don't register them.
Here are some tips on protecting your bike from getting stolen:
1. Do not leave bikes in your yard. Secure them in the garage overnight with the door closed or locked. If you don't have a garage, bring them inside your home at night.
2. Lock your bike and both wheels to an immovable object that cannot be cut or broken. Use a good quality locking device, such as a a hardened steel "U" shaped lock or a hardened steel chain and padlock.
3. Many businesses and parks have bike racks; even if you will be within a few feet from the bike, make sure to secure it, so you can enjoy the day without worrying about it being stolen.