usually only time i need to lock them is if i have them in the back of my truck. i use pretty heavy chain i keep in th bed that could tow a car. so i just brought a padlock (to lock it in the bed itself) and i lock whatever bike i'm carrying with it.
beyond that, i have a chain lock if i want to ride somewhere and be off the bike (not too often), and one bike (i think. i may have taken it off) has a little loop looking lock that attatches where a rear caliper brake would be. you push the button to loop it through the wheel and a key snaps it back. i wouldn't trust for more than if i were still near the bike but maybe had my back turned or something.
beyond that, i have a chain lock if i want to ride somewhere and be off the bike (not too often), and one bike (i think. i may have taken it off) has a little loop looking lock that attatches where a rear caliper brake would be. you push the button to loop it through the wheel and a key snaps it back. i wouldn't trust for more than if i were still near the bike but maybe had my back turned or something.