An ominous tweet from the NYPD's 5th Precinct drew considerable jeering from cyclists and safe streets activists recently. The precinct, which patrols Chinatown and SoHo, announced that due to a dramatic spike in "bicycle collisions," officers would be "enforcing violations by bicyclists."

What did this mean? Because the precinct was promising to crack down on cyclists, one assumes the "increase in bicycle collisions" refers to incidents where a biker is at fault. Stuff like running a red light and hitting a pedestrian, or swerving onto the sidewalk because a squad car is blocking a bike lane.

Days before the 5th Precinct's warning, an officer was seen tackling a cyclist in a bike lane near the Manhattan Bridge entrance. Some wondered if this was the best use of the department's resources, considering the number of injuries and fatalities caused by motorists in the area far dwarfs injuries caused by cyclists.

Others, like Ben Wellington—a Pratt professor who runs the excellent data analysis website I Quant NY—wondered how the NYPD arrived at that 115% stat in the first place. The answer remains opaque. From his post:

It turns out that 2013 had more collisions Year-to-date than 2014, so that must not have been what they were talking about.

2013: 86, 2014: 83

Maybe they were talking only about collisions where pedestrians were injured, since that is usually the cycle ticketing rationale:

2013: 1, 2014: 0

Maybe cyclist accidents that caused deaths, since the aim of VisionZero is to drop that number to 0?

2013: 0, 2014: 0

OK, next try. Cyclist accidents that injured drivers:

2013: 8, 2014: 2

Last one. Number of cyclist collisions where no cars were involved, since this tweet focusses on cyclists, not drivers:

2013: 0, 2014: 1

Ah ha! One reported collision that did not involve an automobile in 2014, vs zero in 2013. A number where 2014 shows an uptick. And in fact it’s an infinite percent increase.

Wellington says he has "absolutely no idea" where the NYPD derived that "115% increase" from. And neither do we. The 5th Precinct ignored Twitter questions about the stat, and the NYPD press office has not responded to our inquiry. We'll update if we get an explanation, but for now just assume that if you're riding a bike, cops will target you for the slightest infraction, which is the status quo anyway. Drivers can keep doing whatever, obviously.