Saturday started cold and got colder, with temperatures falling from 21° before dawn to 9°. Still, thousands of brave — or at least hardy — riders climbed on a ice-cold Citi Bikes and took 6,517 trips, according to Citi Bike spokeswoman Dani Simons.

Saturday was somewhat unique because it was cold and there was no snow on the ground. On similar days over the past three winters — below freezing and no snow — Citi Bike riders took around 9,000 trips on average.

That's based on data put together by Todd Schneider, who did a thorough analysis of data on 22 million Citi Bike trips through last November.

Schneider found that as the weather warms from the 30s to the 60s, ridership climbs steeply to about 35,000 trips on average. Warmer than that and the number of trips start to level off.