In doing some background research I found a recent, May 2007, study done by DCP's department of transportation. You can download it here:

These are the key findings:

1. Most cyclists ride for recreation and exercise.
2. Commuter cyclists ride the most frequently.
3. The majority of respondents use the NYC Cycling Map (78%).
4. When riding on-street, the majority of riders prefer streets with bike lanes and
signs (93%).
5. The majority of cyclists prefer riding on off -street bike facilities to on-street (76%).
6. Cyclists categorized more bike lanes with buff ers and greenways as the most important
designs to be implemented.
7. The majority of cyclists want more on-street bike racks (95%).
8. Cyclists park and lock at sign posts 82% of the time and CityRacks 64%.
9. The most common reason that non-commuting cyclists do not commute by bike
is because of driver behavior/traffic and lack of safe storage at work.
10. The most common reason commuter cyclists do commute by bike is because it is
healthy/good exercise and because it is environmentally friendly.
11. Bicycle commuters have been commuting by bike on average for 5.7 years.
12. Commuters: 44% start in Manhattan and 41% start in Brooklyn.
Commuters: 81% end in Manhattan and 10% end in Brooklyn.
13. The highest number of commuter originations is in the Park Slope area of Brooklyn.
14. At the work place, 52% park their bikes outdoor and 48% park indoor.
15. Commuting cyclists most often encouter problems with vehicles not sharing the
roadway and vehicles parked in bike lanes.
16. The average commute time for cyclists is 35 minutes.
17. Distance between home and work, and having a longer commute by bike does not
keep non-commuting cyclists from commuting by bike.
18. Access to the Manhattan Bridge and Brooklyn Bridge are problematic.
19. The Manhattan side of the Queensboro Bridge and the Williamsburg Bridge were also
cited for having access problems.
20. The majority of commuter cyclists ride round-trip 5 or more times per week (54%).
21. Twenty-nine percent of commuting cyclists connect to other modes of transportation
to reach their destination.