Numbers up

Figures from the Chicago Department of Transportation's Divvy bike-share program show that December through March trips jumped more than 200 percent to 518,286 in the winter of 2015-16 from 167,258 in the winter of 2013-14.

Some of this is likely because the 2013-14 winter was unusually cold, while last winter was unusually warm, and Divvy has been expanding, department spokesman Mike Claffey noted.

But the trend continued this winter, which has been cold. The number of Divvy trips taken this past December, which had below-normal temperatures, was 93,275, lower than the December 2015 number of 121,141, but still higher than the December totals in 2013 and 2014, which were 44,694 and 86,800, respectively.

Motivate, which runs Divvy and other bike-share programs across North America, also has seen big spikes in winter biking in New York City and Boston, spokeswoman Dani Simons said.

"People are starting to make bike-share a year-round transportation choice," she said. Simons noted that some users bike to transit stations instead of walking. "It may be a way to speed up your trip in cold weather."