Last week's announcement that Portland is America's #1 bike commute city created a lot of discussion on the blog, so check out this statistical tidbit: there's a roughly 3 percent bike gender split among Portland bike commuters. In 2008, 7.3 percent of Portland males reported their bikes are their primary mode of transportation to work compared to 4.4 percent of women.

This is a nationwide trend that likely has a lot of roots and Portland has recently started organizing women on bikes promotion programs. I called up two female bike advocates to see what they thought creates the biking gender split.

FACT! Women outnumber men on tiny pink and/or blue bicycles 2:1
  • Via Sprockettes.org
  • FACT! Women outnumber men on tiny pink and/or blue bicycles 2:1

Bicycle Transportation Alliance staffer Steph Noll is coordinating this year's bike commute challenge and attributes the gender split mostly to safety concerns. "The conventional wisdom is that women identify themselves as more concerned about safety. Conditions have to feel safer for women to bike," says Noll, identifying infrastructure like bike lanes and separate bike boulevards as key to getting more women on bikes. "There’s a lot of situations where people are just as safe riding in traffic, but they don’t feel safe so they’re not going to try it."

In places without many bike lanes or good paths, women can get turned off to biking because it requires a more aggressive attitude, says Noll. "Years ago in any major American city you had to feel tough and aggressive to bike in any major American city and assert yourself on the road."

The Mayor's Transportation Director Catherine Ciarlo, who bikes with her four and seven year old kids on an Xtracycle, points out child-rearing duties as a factor keeping women off bikes. "Women are often tasked with more household and child responsibilities, which means multiple trips and different kinds of bikes and different kinds of arrangements. It’s kind of a supernatural feat to make it work by bike and I mostly do, but there aren’t a lot of models out there to make that easy," says Ciarlo. Not only do you need a bike that can safety fit your kid, but to see other women riding bikes, too. "Picturing yourself doing it is easier because someone else who’s perfectly normal is doing it."

Update 2:43 pm— A couple readers sent along this interesting Scientific American article about women on bikes. It quotes a PSU researcher and notes that the U.S. biking gender split stands in contrast to biking demographics in Europe.

P.S. The crappy graph on last week's post about commuting made it look like the number of people using public transit had dropped. The numbers from the Census show that 12.7 percent of Portlanders used primarily public transit to get to work in 1998 compared to 13.4 percent in 2008. Carpooling, though, dropped two percent and driving alone fell from 68.6 percent to 64.6 percent. Just FYI.