What natural features and governmental conditions contribute to a bicycle friendly town/city?
Down vote notwithstanding, here are some thoughts:

Living in Boston and bicycle commuting both 4- and 3-season for 15 years, I'd say there at least four factors, governmental, NGO, population, and environmental.

The NGO aspect would be - how many organizations there are, and how actively do they advocate on behalf of cyclists. In Boston/Cambridge/Somerville, and Massachusetts at large there are at least two, Mass Bike, and The Boston Cyclists Union. I'm not a "joiner" so it's possible there are others, say, Bikes-not-Bombs, that have a different agenda, but still, a degree of visibility, and advocacy. 

Because Boston metro has a very significant student population, and conversely tight parking situation, many people ride bicycles. By way of sheer numbers, organizations have a significant number of folks they can represent, as well as interest and energy to recruit from.

The governmental aspect would be, how interested in alternative transportation is the current state and local administration? Is there a "Bike Czar" appointed by the city that acts as liaison to facilitate communication between constituents and DOT, or the mayor's office. How interested is the city or state, in facilitating alternative modes? 

Beyond that, how conducive to cycling is the geography, and the weather? The Dutch live on flat land in a maritime environment that tends to favor the widespread adoption of the bicycle. Combine those with the impossibility of parking and you have something of a perfect storm. Portland if I'm not mistaken, has a similar maritime weather pattern, as does Boston. An educated population, and short distances to major areas helps as well.

On the other hand, Minneapolis is frigid and spread out, but there is a huge cycling community. They have a significant "rails to trails" movement to re-purpose unused arteries that run far and wide. Native infrastructure matters.

Boulder has a larger hippy/ hipster/ outdoorsperson population that take to the bike.

So, sitting here pondering it, you get the sense there are many factors at play.

Ride it like you stole it!