Bike theft is pretty much nonexistent here (penn state) - if its not near a major city, I wouldn't really worry about it. I have friends with $450, $550 and $900 bikes who lock the frame only with kryptoloks or Bell U-locks, and cheaper bikes with just a cable. There's also this 105-equipped Trek I always see in front of buildings locked with just a cable, and it hasn't vanished yet.