Minneapolis versus Portland: This is shaping up to be quite a rivalry.

Today, Pacific coast sustainability standard bearer Portland topped Midwestern standout Minneapolis in Bicycling Magazine’s bike-friendly city rankings, bi-annual source of bragging rights or shame, depending on your locale.

The top-two results were a reversal of the 2010 rankings. Bicycling Magazine did not explain what boosted Portland but did mention the city’s stature as the only large city to receive the League of American Bicyclists’ “Platinum-Level” Bike Friendly City Award, as well as its tendency to be the earliest of early adopters when it comes to innovations like bike boxes (Portland had the nation’s first).

Meanwhile, Minneapolis recently snagged national bragging rights with its Bike Score — the new bikeability scoring system that the creators of Walk Score unveiled last week.

Overall, big cities enjoy a growing prominence in Bicycling’s top ten, reflecting a trend in bike-friendly political leadership in America’s major metropolises.

While tiny Boulder, Colorado took the bronze, Washington, DC came in an impressive fourth place, boosted by its enviable bike-sharing system.

“There is no clearer evidence of the urban-cycling revolution sweeping the United States than in the nation’s capital,” wrote Bicycling’s Ian Dille, “where ridership jumped 80 percent from 2007 to 2010.”

Also surging ahead was Chicago, taking fifth place. Mayor Rahm Emanuel’s plan for 100 miles of protected bike lanes was cited as a big factor, along with the popular Bike-the-Drive open streets event.

New York City, which will be launching the nation’s largest bike-share system this summer, ratcheted up one spot to seventh place, on the strength of the bike infrastructure built on the watch of Transportation Commissioner Janette Sadik-Khan. San Francisco dropped a few places to eighth. And Seattle rounded out the top ten.

Smaller trailblazers Madison, Wisconsin and Eugene, Oregon slotted into sixth and ninth place, respectively.

Bicycling Magazine’s rankings are based on data from the League of American Bicyclists and the Alliance for Biking and Walking along with input from local advocates. Fifty cities are ranked this year, from Des Moines, Iowa to Miami, Florida. To qualify, each city “must possess both a robust cycling infrastructure and a vibrant bike culture,” according to the magazine.