Bike score: 68.4
Percentage of bicycle commuters: 2.3%
Really. According to a study from the University of California at Berkeley, 37% of Philadelphia workers commute without a car, compared to 33% for Chicago and 45% for San Francisco. Overall, 13% of Philadelphia households do not own a car. In Philly that leaves you with only a few options: The much-maligned trains and busses of the city's SEPTA system, bikes or a really good pair of walking shoes.For more than 35,100 people, that means riding their bike to work. While Philadelphia's made some modest improvements to its bicycle infrastructure, the density of downtown and the trails along its rivers make this town more bikeable than its congested streets and big swaths of highway suggest. There's still a lot of work to be done, but when you combine one of the largest bicycle commuter bases in the country with enough shops, groups and infrastructure -- including Philly Bike Share, which arrives next spring -- the safer streets tend to follow. Slowly. 5. Denver
Bike score: 69.5
Percentage of bicycle commuters: 2.9% Fort Collins has more than 280 miles of bike lanes, the Fort Collins Bicycle Library for bike lending and bike-friendly New Belgium Brewing Company hosting bike-in movies, races and scavenger hunts. Boulder has one in 10 people has more than 300 miles of trails and one in 10 residents taking their bike to work. How does Colorado's biggest city compete? By not only filling its city with bike lanes, but putting more than 850 miles of paved, off-road, bike paths in Denver parks and along Cherry Creek, the South Platte and other bodies of water. Oh, and by launching its citywide B-Cycle bicycle sharing program more than five years ago and growing it into one of the biggest in the country. The League of American Bicyclists has rated Colorado as the second most bicycle-friendly state in the nation, and Front range cities like Boulder, Fort Collins and Denver have been a huge part of that push. By legislating bicycles and bike safety into positions of priority, Colorado cities have made them a vital part of the state's transportation system and have normalized bicycles as an accepted mode of commuting and recreational travel. Bikes are as much a part of the landscape here as the Rockies, and they're not going anywhere anytime soon.