I lived in Boulder County and frequently cycled in the city of Boulder, and I can attest to the bike friendliness and amazing cycling opportunities there. Boulder residents began building for non car transportation in the 60s. Last year, 46% of the city's transportation budget was spent on cycling, pedestrian and public transit projects! The 2008 Census community survey released last month shows that 10% of commuters ride their bikes to work.
Via 303 Cycling.