OnGuard Doberman 5028 Cable Lock
If you're not in the city, a cable lock is usually all you need. Bike thieves usually don't venture out into the suburbs because, strangely enough, invisibility is easier in the city. Because of this, bike theft is more rare in the burbs. Still, there will be the occasional person looking to steal something for a quick rush, so a simple cable-lock usually suffices to prevent this. The key-entry OnGuard Doberman cable-lock is easy to maneuver, easy to use, and easy to cart around. For twenty bucks, it's definitely affordable.