Use one good lock and a few other lighter locks (or several good locks if you have room to carry them all and don't mind the weight). I use a Kingpin lock made by Norco in addition to a cheapy chain combo lock and a 6-foot braided cable lock that is looped all around my bike, locking all wheels and the rack to the frame. Thieves will not even bother with three locking mechanisms and move on to the next bike with just one $15 cable lock. Thieves gonna thief...just make sure it's not your bike.