I've got an OnGuard Pit-bull U-Lock/Cable Combo but its heavy so I tend not to take it unless I know I'm going to lock it up some place for a while. I'll take a lighter cable lock for really quick runs were I might need to use it but to tell you the truth I almost never leave my bikes were I can't see it even if its locked and if I have no lock I don't leave it, unless its on our tandem in which case the wife stays or I do and a lot of times I'll lock it even if she stays if I have my cable with us.