Today, Citi Bike opened up a treasure trove of data on how people are using the system, giving the public access to details of individual trips, featuring information such as starting point, ending point, trip time, bike identification number, and anonymous information about the bike user, including gender, age, and whether the rider was  using a day, week or annual pass.

With today’s news, Citi Bike has joined sister systems in Washington, Boston, and San Francisco in releasing data about individual bike-share trips, not just aggregate data on the total number of trips and members.

The data, from July 2013 to February 2014, gives the public an opportunity to look for patterns in how New Yorkers and tourists use bike-share. To prepare its release, Citi Bike worked with NYU’s Rudin Center for Transportation Policy and Management, which got a head-start on analyzing the data.

“We got it about three weeks ago,” said Sarah Kaufman of the Rudin Center. “September seemed to be the most interesting [month of data],” she said. “Everyone is going to work and school and the temperature is still temperate enough that people are still interested in biking.”

Kaufman, along with Jeff Ferzoco of linepointpath and data visualization specialist Juan Francisco Saldarriaga, sorted through the data to create maps and animations.

Some patterns jumped out as the group began its work. First was the difference between annual members and riders using day or weekly passes. “The casual riders, they’re clearly tourists,” Kaufman said. “They’re concentrated around the Brooklyn Bridge, the World Trade Center site, the bottom of Central Park.”

Another pattern that emerged: Late-night bike-share rides, especially on weekends and holidays, often involve pairs of riders going from the same starting place to the same destination within a minute or two of each other. “People are biking together,” Kaufman said. “It’s interesting to see these Citi Bike couples.”

A third pattern: a slight correlation between unplanned MTA service disruptions and Citi Bike ridership. “It shows the potential of Citi Bike to become really intricately interwoven into the New York City transportation landscape,” Kaufman said.

Observational studies of Manhattan cyclists have shown that women make up a higher proportion of Citi Bike riders when compared to the cycling population at large. The data released by Citi Bike today includes gender information, and the group is working with WNYC on a project to look deeper at the age and gender demographics of Citi Bike users. “I think that’s going to be very interesting to dive into,” Kaufman said.

Citi Bike is encouraging the public to share its creations and visualizations using the newly-released data with the #citibikedata hashtag. Each week for the next four weeks, Citi Bike will choose a favorite project and award its creator a free t-shirt. (Alta systems in other cities, including San Francisco and Chicago, have launched robust data challenges featuring a panel of judges.)

One set of data that’s missing from today’s release: GPS information. Unlike other systems, New York City bike-share is designed to include information on the routes its riders choose, not just their starting and ending points. Streetsblog asked Citi Bike if it is collecting this information and plans to release it. We’ll let you know if we hear anything back.