Yes, I used to bike in New York City!
But I did not go on bike during regular work days, as there was simply too much traffic to feel safe. Especially, the streets around Midtown are not the most friendly. However, whenever I had to work a weekend, I would to go the office by bike and really enjoy it.
The City of New York is perfectly designed for bikers: relatively flat and with these wide Avenues stretching North to South of which easily one lane could be taken off for the bikes.
This is slowly happening here and there around the city. In total since 2007 already more than 30 miles of biking lanes have been established - most of them not that safe, as they are simply painted on the street, but on Upper Westside they've understood it the right way (dare I say the Danish way!). Here on a stretch of Columbus Avenue, the bike lane is right next to the pavement, then the parking spots for cars are marked separating nicely the bikes from the fast traffic. Unfortunately, this new and nice biking lane suddenly stops and you are at the mercy of the direct traffic again! If just two Avenues could be adopted accordingly with one such protected and safe bike lane, one going South and one going North, I am sure New Yorkers will start feeling the advantage of taking their bike to work rather than the car or metro.
But it's not only the city planners that need to adapt, also companies and building managers need to provide for lockers, showers and safe parking for bikes - a small investment for companies to do when at the same time their employers obtain a better health!
Forty percent of Copenhageners use their bikes to work - New Yorkers could very well do the same!