Since 2006, Detroit has painted 170 miles of new bike lanes on city streets. People on bikes followed: The Motor City now has the fastest-growing rate of bike commuters in the country.

Bike commuting grew over 400% in Detroit from 2000 to 2014, according to a new report the League of American Bicyclists, which pulled from census data. The city doesn’t have as many new bike lanes as some cities (Tucson, for example, has over 600 miles of lanes). But culture might be pushing some of the growth, like Slow Roll Detroit, a weekly bike ride that can pull in more than 4,000 riders at a time.

Fastest-Growing Biking Cities:

1. Detroit, MI

2. Pittsburgh, PA

3. Cincinnati, OH

4. Portland, OR

5. St. Louis, MO

6. Chicago, IL

7. Cleveland, OH

8. Washington, DC

9. Milwaukee, WI

10. Oakland, CA

“Slow Roll started out completely grassroots, but it’s something that even the city of Detroit is starting to embrace as a way for more people to be introduced to biking, to see what it feels like to bike on the streets,” says Amelia Neptune, a program manager at the League of American Bicyclists. “For a lot of people, that might be the only time they’re on a bike in Detroit, but I would not be surprised if there was a correlation between people participating in that ride regularly and then maybe the next Monday thinking ‘Okay, I can do this, I’m going to try it on my own on my way to work.'”

A cyclist in Cincinnati, Ohio. Flickr user 5chw4r7z

The total number of bike commuters is still low–less than 1% of the population, compared to 23% in the uber-bike-friendly town of Davis, California, or almost 10% in Berkeley. But the fast growth rate is likely to continue; Detroit rolled out its first protected lanes this summer. Cities like Pittsburgh and Cincinnati also have skyrocketing growth.

New bike lanes are a big part of the growth, but not all of it, Neptune says. “We talk about the building blocks of a bike-friendly community, and it really takes several pieces–focusing on not just the infrastructure but also on education, the policies and laws to protect cyclists, and planning.”

St. Louis, Missouri Flickr user Trailnet

And there’s a long way to go, if you compare U.S. cities to bike utopias like Copenhagen, where around half of commuters ride to work. “That hasn’t always been the case there,” she says. “They’ve put in really amazing infrastructure and the culture over time changed. In the States you see the same thing, in places like Davis, [California] that had the infrastructure and staff time dedicated to becoming a bicycle friendly community, those are the places where you see really high numbers of bike ridership. So I think over time it’s going to keep growing.”

The most interesting part of the list of fastest-growing cities for bike commuting might be the fact that many on the list are unexpected. Bike commuting is growing throughout the entire country, not just in the traditional coastal hubs. “You see rural communities, you see small communities, you see places geographically spread out. It’s diverse across the country,” says Neptune.