Total bike lane distance: 124 miles
Trips made by bike: About 50 percent
While Amsterdam usually gets the spotlight, Groningen's the hidden gem of the bike world. For every resident, Groningen has 1.5 bicycles, which makes sense because the center of town's basically off-limits to cars thanks to local regulations. It's a big college (aka party) town, too: One out of every five people here is a student, with most between the ages of 20 and 24. Oh, and some bars in the city center are open 24 hours a day.