I have not locked it as I usually don't venture far from the bike. I do however have a coiled cable that I can carry if I know I am going to be away from the bike. I do lock with 2 cables when the bike is on the trunck mounted rack. Cable the 2 wheels and frame to the tow eye under the bumper. Cabling to the rack is useless as a thief can cut the straps and carry the whole thing away.

T