I'm looking into buying a bicycle, and it seems I would be best getting a decent lock with my purchase. I've handled the Kryptonite New York Fahgettaboudit chain lock, and the thing, it felt, weighed close to ten pounds. I want to be safe, but, honestly, I don't see myself lugging around ten pounds of steel just to lock up by bicycle, and, if it's what I buy, I'm almost certain I'll ride less often (not something I wish to do).

Are there any other "good" options? Yes, the bike will sometimes be locked up outdoors in a large city, and, from what I've read, a thin "cable lock" probably will be too flimsy to rely on.

Would a high-quality U-lock be good? Would a Kryptonite U-lock, for instance, be as strong as one of their chains? How would the weight be?

Thanks much.