There's not much in the way of lane discipline on NYC's avenues. Imagine a race course 4-5 lanes wide, with everybody jockeying for position, trying not to get caught behind a slower car, or trapped against the boards. Cyclists need to stay out beyond door range, but depending on their skill, speed and confidence make lane changes, around double parked cars, cars making left turns, trucks, cabs and jaywalking pedestrians.

When I cycle NYC avenues, I keep left, but shift right one lane every other block to not trapped by cars turning left. NYC streets are mostly one way, alternating every block).

To new commers NYC riding can be very intimidating, but once you have a sense of how things work it's not unreasonable, and I actually find it safer that riding in the burbs. One bright side of NYC riding is that the bike and auto speeds are very closely matched making maneuvering easier. On some avenues, I often found myself being one of the fastest vehicles, and more concerned about sudden stops in front, then being hit from the rear.