"People tend to buy the big clunky U-locks because they don't know how to use them properly. A U-lock should go around the rear rim and tire, somewhere inside the rear triangle of the frame. There is no need to loop it around the seat tube as well, because the wheel cannot be pulled through the rear triangle."
Thats the part I don't get, can the thief just take an an adjustable wrench and get the wheel off by angling the wheel/still attached lock? Then he can leave the wheel and have the rest of the bike?