Members of Slow Roll Chicago ride in mid-January. Numbers show more people aren't putting their bikes away just because winter weather sets in.

CHICAGO — It may be 5 degrees below zero with the wind chill, but Matt Barrington, 31, of North Lawndale, still bikes to work every day.

“It’s nice to get some fresh air every morning,” Barrington said. “Once you get going, you get warm pretty quick.”

Barrington is one of a growing number of Chicago-area commuters who are riding bikes despite snow and frigid weather, according to cyclists, bike shop owners and Divvy numbers.

The number of winter bikers has spiked in recent years due in part to improved infrastructure, such as protected bike lanes, and better, cheaper cold-weather equipment, cyclists and bike dealers said. Other factors include the expansion of Divvy, which gives commuters an alternative to using their own bikes in the salty slush, and a mild winter last year that encouraged people to give cold-weather biking a try.

“Last year it exploded,” said Manuel Tenorio, owner of Johnny Sprockets bike shops. He said last year’s winter brought out more people, and the numbers kept climbing this year despite lower temperatures.

“It’s in the air, much like the salt gets in the air this time of year,” said Dave Glowacz, known as “Mr. Bike,” who wrote the guide “Urban Bikers’ Tricks and Tips.” “People are influenced and inspired by seeing other people doing it.”

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.

Summer is the peak time for biking, with just under 500,000 Divvy trips taken each month, Claffey said.

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

EQUIPMENT MATTERS

Tenorio and other bike shop owners say better equipment is helping cyclists go year-round.

In January, Pedal & Spoke bike shop in North Aurora, Ill., hosted a demonstration of bikes with fat tires, which are 3 to 5 inches wide instead of the 1- to 2-inch width of traditional bike tires, said owner Ashton Brackett. About 50 people crowded into the shop, with most going out on a group ride despite the bitter cold, Brackett said.

“People are becoming aware that it is possible to stay active during the winter,” Brackett said. He said fat tire bikes have come down in price.

Also dropping in cost are good lights — necessary for short winter days. Brackett said the price of a 350-lumen rechargeable bike light has dropped from $120 to about $50.

Some winter bicyclists favor specialty gloves called “pogies” that look like oven mitts and snap onto handlebars. Other options are “gunner” gloves.