Abus 6000 Bordo 2.6'' Folding Lock
Is it a chain? A U-Lock? A cable? What is it?! Well it's definitely not a cable lock because those are worthless. The Abus Bordo is a folding lock. What does that mean? It means it folds like a chain with the strength of a U-Lock. It easily attaches to your frame, adding no extra weight to your basket, bag, or pocket. This lock is anything but cumbersome, so there's no reason not to have it - especially if you already feel cumbersomed by your current lock.
And if you know anything about us, then you know we believe one lock just isn't enough. No bike is un-stealable, but the more time-consuming your pony looks to unhitch, the more likely you two will ride home together in harmonious bliss after enjoying that soy latte at the coffee shop where the cute barista works who got you into bike riding in the first place, and is always asking how your cat's doing.
So get two locks. Get three locks. Just don't use a cable lock because in that case you might as well stand there waiting for those pesky thieves to show up so you can help them load your bike into the back of their truck. You've been warned.