8. Portland, Ore.
Number of bicycle commuters: 16,846
Bicycle commuters' share of overall population: 5.8%
Spend a little time in Portland and and you'll become a quick study in local bicycle law.
Even in a city with more than 250 miles of bike lanes and trails and a student population hovering around 10%, bikers are extremely aware of which paths and streets they have access to, where their access is restricted and where the friendlier confines of the city's 40-Mile Loop of greenway lies.
The result is a city in which about 8% of the commuting population takes a bike to work, where a local dairy has a velodrome on its property that hosts races all spring and summer long, where cyclocross races in the fall draw thousands of spectators and where the Portland Timbers Major League Soccer team has guarded bicycle parking for fans attending games at Jeld-Wen Field.And if cyclists feel like riding their bike around town nude, that's just fine as well. Portland hosts a leg of the World Naked Bike Ride each year and just welcomed more than 10,000 naked riders to town in June. As long as riders are familiar with bike law, their al fresco ride won't get them into any trouble; the last time Portland police tried to arrest one of the naked riders three years ago, Judge Jerome LaBarre dismissed the charges against the clothing-deprived defendant on the grounds that nude bike riding is a "well-established tradition" in Portland. Oregon's bicycle law covers a lot of ground, but doesn't require you to be covered while obeying it.