City officials have taken no small amount of pride in the city's jump to No. 2 among the city's 50 largest cities in its share of residents who commute by bike.

But the city dropped two notches to fourth in the latest American Community Survey by federal census officials. The 2010 survey found 3.5 percent of residents aged 16 or older commuted to work the previous week primarily by bike. That's down from 3.9 percent in 2009 and even more from the peak of 4.3 percent in 2008.

That puts the city behind three West Coast cities – Portland, Seattle and San Francisco – although the gap with San Francisco is small enough that it disappears if the numbers are rounded.

What's going on?

First, the 4.3 percent peak could have been a statistical blip. The annual survey uses a small sample, and the margin of error means 2010's 3.5 percent could vary from 2.8 to 4.2 percent.

Another possibility is weather, noted Simon Blenski, a planner working for the city's bike program. The survey questions residents continuously throughout the year, meaning that some people are surveyed during the winter weather that discourages many bike commuters. Blenski notes that last winter got early snow, and was one of the snowiest on record, while the winter before got a hard crust of ice from a Christmas rain that froze. But the city's annual count each September also showed a slight dip in bike riders for 2009 and 2010.

Commuting in Minneapolis

Blenski said that survey numbers in future years should be interesting to follow, given the city's expansion of bike facilities this year. "A lot of the projects we're planning just went in this summer and fall, and some won't be fully realized until next year," he said.

But city bike commuters can take solace that their commuting rate is still three times higher than the metro area as a whole. And it's notching the best record by a wide margin of any snow city among the nation's 50 largest.