So, what are some of the best bike friendly cities? Well, Copenhagenize Consulting is glad you asked. Last year it created an index based on 13 criteria. The inaugural ranking assessed 80 major cities worldwide and ranked the top 20. Below is the top 20 list along with corresponding city data such as population, land area, and density compiled by Coventry League using Wikipedia (each city's page) and web research. You may download a PDF version for free.
And, if you want to research more about world cities, the website City Mayors has a lot of interesting data.