Biking is a great way to stay healthy and get around town without paying for gas, but not everyone bikes in equal numbers. There’s a gender gap in bike commuting, one that’s easily illustrated by bike-share numbers. Several years after its launch, the membership of New York’s Citi Bike program was less than a third female, and it isn’t a problem that’s unique to New York or bike-sharing in general.

A good way to get more women cycling, though, is to install more bike lanes, as researchers from the University of British Columbia and the University of Colorado concluded in a recent study in the Journal of Transport and Land Use. It sounds intuitive and, indeed, studies have shown that adding bike infrastructure leads to more people biking in general.

But it’s particularly important to talk about how to get women on bikes because the gender gap in cycling is so large in the U.S., even though the approximately equal shares of women and men biking in Europe tell us that riding a bike isn’t a uniquely male activity.

The latest study examined cycling demographics by neighborhood in Montreal and Vancouver, two cities that both have a diverse selection of bike infrastructure ranging from painted lanes to cycleways separated from the street. The researchers found that if a neighborhood had access to some kind of bike infrastructure within about half a mile (1 kilometer), that area saw four times as many people cycling as neighborhoods without bike lanes. But the difference between cycling on the road with cars and cycling in a dedicated lane of some sort had an even more significant impact for women specifically.

Though women make up half the commuters in Montreal and Vancouver, they were much less likely than men to ride bikes to and from work if there wasn’t any bike infrastructure. In some neighborhoods without infrastructure, only a tenth of the cycling commuters were women, while in one with better access to bike lanes, women made up almost half of the cyclists. When more bike commuters were hitting the road in a neighborhood, the percentage of men and women was about equal, perhaps because of the “safety in numbers” phenomenon.

The percentage of commuters in each neighborhood who get to work by bicycle, with darker colors indicating a greater share.

Teschke et al., Journal of Transport and Land Use , 2017

“To give women an equal opportunity to bike to work, municipalities need to build a great quality cycling network,” Kay Teschke, a professor of public health at the University of British Columbia and the study’s lead author, said in a Q&A with UBC’s news team.

The new study data, taken from 2011 Census results, may paint a slightly different picture than you might find in those cities now, six years later, when there might be new bike lanes or more bike commuters. Not to mention the fact that bike lanes aren’t necessarily spread evenly throughout a city, so other factors may be influencing this data, as the researchers admit. For instance, wealthier neighborhoods tend to have better bike infrastructure, which is why bike lanes have become a symbol of gentrification. But the results do track with previous research on the subject. A study in 2013 found that women cared more about cycling near bike paths or trails than men did, and several studies have found that women are more concerned about the safety issues associated with riding a bike than male riders.

Whether for men or women, though, the study makes it clear that cities could do a lot more to encourage cycling. People were more likely to bike if their neighborhood had an interconnected web of bike lanes, not just a few scattered paths. “The pattern of results suggested that the network formed by other bikeway types may have been more important than the specific bikeway characteristics,” the researchers write.

“Even though biking is faster and easier, more people walked to work than biked to work in both cities,” Teschke noted in her Q&A. She suggests that one reason could be that sidewalks are ubiquitous, but bicycle lanes are not—and whether men or women, people are apt to choose a mode of transport that makes them feel safe over one that’s a little more convenient but makes them think they’re about to get run over at any minute.

And while it might not seem that important to get women on bikes, cycling has major benefits that, ideally, the whole population should enjoy. Surveys find that people who cycle to work are happier than other types of commuters, and a 2016 study found that cyclists in the Netherlands outlive non-cyclists.