I should note that Baltimore has a decent sized car-free and car-light population but our bus system stinks (one of the worst in the country for a metro area.) It’s also interesting to note that areas that have larger concentrations of biking also include alternate routes (not always a grid but at the same time do not force everyone on one road for any kind of trip.) In contrast with the DC metro area biking seems to flourish along the (metro) rail lines and trails that interconnect and does not seem as dependent on the road system being a grid or having alternate routes.
One common thread that I have noticed that transportation mode choice seems to be very dependent on time. People are more likely to use alternate transportation if the can get to work in a half hour and somewhat likely if they can get to work in an hour. And the selection of biking as a choice is dependent on if other people are doing it which is mostly dependent of some significant bike facility nearby that can be biked to or a general economic situation such as around collages.