This afternoon, my wife and I rode our beloved, vintage Bob Jackson tandem down the West Side Greenway to the Museum of Jewish Heritage near Battery Park. I was a little worried about leaving it outside. Turns out I had nothing to worry about.
We locked it to a bike rack out front, with two policemen looking on. On the street were at least six NYPD cars, apparently providing security to the museum. When we came out over two hours later, the same cops were standing in the same place, about ten feet from the rack. I really didn't need to lock it up at all.

Heh, amusingly enough, my son and I were on a bike tour in August that went down the Hudson greenway and passed by the Heritage museum. I wanted to go in, until I noticed the scattering of cut U-locks around the rack. Our little cable locks wouldn't have stood a chance.

I wouldn't leave a decent bike anywhere in Manhattan without somebody nearby watching it. Those cops may have been there, but you didn't know they'd still be there later. Most locks are a joke, even my NY Fuhgeddaboudit.

That said, I do see a number of bikes in front of my office building that are there almost every day, and are fairly nice at that. I'm just saying I wouldn't do it.

I would not NOT lock a bike. The police aren't going to remember who left what two hours earlier, and a confident person who looks like they know what they are doing can get away with a lot.

The safest place to lock a bike in NYC is in your apartment, not your buildings store room, but in your own apartment

Or around your waist.... seriously though, I wouldn't lock any bike up outside and leave it alone in NYC unless you're think you can deal with it not being there when you get back.

The times i leave my bike outside City College of NY I use a fugettabout it chain and two NY ulocks. And even then I still feel the need to come back and take a look. Luckily i just leave the locks there so i dont have to carry it