Our headline is a tweet from TreeHugger Emeritus Jacob Gordon, and neatly tells the whole story; the longer version is in the New York Times, which printed not a few column-inches of stories trashing CitiBike before and after it started. The probable reason for the surprising run without fatalities:
Safety in numbers.
Charles Komanoff, a transportation economist and avid biker, suggested that the “safety in numbers” phenomenon had spawned a helpful cycle: The increase in biking in recent years has made the practice safer, which has encouraged bike-share ridership, which should in turn improve safety for “incumbent cyclists.”
Paul Steely White, the executive director of Transportation Alternatives, said some of New York’s drivers were beginning to behave like those in major international cycling hubs. “People just expect to see them around every corner and around every turn,” he said.
The people that Dorothy Rabinowitz of the Wall Street Journal called "faceless road swipers" who were begriming the city turn out to be pretty good at sharing the road. The obnoxious blue bikes that were going to knock Delia Ephron over didn't.
This lucky streak won't last forever; it may be a statistical blip, given that ten other cyclists, not on CitiBikes, have been killed so far this year. No doubt when the first one happens it will make all the headlines, topped with "I told you so." But so far, it is nothing but good news. More in the New York Times.