Possible subheading: Why cycling can be a better solution to transit and congestion problems than subway and bus spending. These maps show definitively that within a certain radius, cycling will get you around a city effectively, regardless of whether or not you have mass transit options.
Now, I think that their methodology short-changes transit, specifically buses. If a bus comes every 20 minutes, then that will show up as an average of ten more minutes of elapsed time on this comparative map. That means that for people with the ability to schedule their transit (i.e. most of us), buses would probably make mass transit more effective.
That being said, I know from experience that single-mode transport is most effective, and that a decently in-shape cyclist can get around Boston faster than the subway can over short distances. Over longer distances, it becomes a question of whether or not the destination has parking.