A new guide will help cities establish their own bike sharing programs.

Bike sharing programs are reaching critical mass across the globe. With around 600 bike share systems in cities worldwide, they are fast becoming a necessary part of cosmopolitan life, says Colin Hughes, director of national policy and project evaluation for the Institute for Transportation and Development Policy (ITDP).

Bike sharing is a bit more complicated than hopping on any bike on the street, though not by much. Docking stations are installed throughout a city with bikes to rent and an electronic pay station, though sometimes they’re manned by station agents. Most programs offer annual subscriptions that allow for an unlimited number of rides per year for a set amount of time for each ride.

To take a bike, you insert your credit card into the pay machine, pay a rental fee, and then unlock a bike from those at the station. Riders typically have a window of about an hour to ride wherever they want and return the bike to any another docking station.

Bike shares aren’t just useful for reducing traffic and offering a quick way to get from a metro stop to work (or home from the bar afterward). By offering easily accessible bicycles, bike share programs lower the threshold for exercise, which can help people lose weight.

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“Active transportation has been shown to reduce the risk of obesity significantly, and there is an obesity epidemic in America right now,” Hughes says.

Active transportation, according to the Centers for Disease Control and Prevention (CDC), includes things like bicycling and walking. Anything that gets people moving instead of sitting in a car or on a train can help prevent weight gain and reduce the risk of stroke, diabetes, and death, the CDC reports.

Even the federal government is taking notice of cycling’s health potential.

In San Antonio, Texas, where nearly 66 percent of adults and 32 percent of children are overweight or obese, the CDC has sponsored a bike share program as part of an initiative to promote healthy living. To date, the San Antonio Bike Share reports 20,000,000 calories burned, and 380,000 pounds of carbon dioxide offset.

And low-resistance cycling is low-impact, so it’s a good exercise even for those suffering from joint pain.

In addition to helping burn calories, bike share programs can also contribute to cleaning up air pollution. That means better air quality and a reduced risk of asthma and other respiratory problems.

“[Bicycling] has no tail pipe emissions, no green house gases, and no impacts from oil drilling,” says Ralph Bormann, a spokesman for the Bay Area Air Quality Management District, which oversees the Bay Area Bike Share program in California. “Cycling is something nearly everyone can enjoy. It’s clean, it’s affordable, it’s healthy, and it’s a fun way to get around.”

In the San Francisco Bay Area, cars and trucks account for more than 50 percent of all air pollution, Bormann says. “So the extent that we’re able to reduce emissions from this sector, the Bay Area can maintain and attain national air quality standards and reduce green house gases,” he said.

The ITDP recently released its Bike Share Planning Guide to help other cities set up programs of their own.

The organization outlined five essential elements for an efficient and cost-effective bike share: having 16 to 25 stations per square mile, 10 to 30 bikes for every 1,000 residents, a minimum coverage area of about four square miles for the whole system, quality bikes complete with a front basket to carry things like groceries, and easy to use rental stations.

With better weight management and air quality up for grabs, it’s time to get cycling.