Decide how much lock you need to carry to feel secure ... knowing that you either have to carry ten pounds of metal which thieves can cut---but very few-- or a lightweight cable which ways several ounces and many thieves could cut--but few will.

I have no real numbers to support it ... but it seems most thefts are thefts of convenience. A cable will discourage a lot of lazy, half-hearted thieves because the three-to-five minutes it might slow them down is more than a cheap bike is worth to them.

Anything more than a few minutes' running into a store with my bike in a high-traffic area, i use a hardened steel chain and a padlock. Because none of my bikes are worth Big Bucks, (if they were I wouldn't lock them up outside) I am not worried about the guy with the hydraulic floor jack or angle grinder. The guys who bother to carry a grinder and spare batteries will get your bike unless you lock it in a bank vault--unless it isn't worth the effort..