"After being named runner-up in our last round of best bike city rankings in 2010, Portland reclaims the top spot. The only large city to earn Platinum status from the League of American Bicyclists is a paragon of bike-friendliness, with 180 miles of bike lanes and 79 miles of off-street bike paths. Always quick to embrace cyclist-friendly innovations, Portland was the first city in the United States to implement bike boxes at intersections and elementary-school bike commuting trains. Among the city's many bike shops is newcomer Go By Bike, which is located under the aerial tram and offers valet parking, rentals, and repairs."
Rounding out the Top 10:
2. Minneapolis
3. Boulder
4. Washington, D.C.
5. Chicago (which I think should be ranked higher)
6. Madison
7. New York City
8. San Francisco
9. Eugene
10. Seattle (Strange, considering our sister city to the north has the nation's second highest rate of daily bicycle commuting.)