Like many Americans, Tara Collins hadn't bicycled much since middle school. That changed this year when she started paying $50 to fill up her gas tank.
"When that happened I thought, 'Wow, there probably are things I could learn about safety,' " says Ms. Collins. "I haven't been on a bike in years, and even when I did, it wasn't in traffic."
The high price of gas is creating a surge in bicycle commuting across the country, not just in West Coast cities but in places like Louisville, Ky., and Charlotte, N.C. The rush of newbies has triggered tensions with drivers unaccustomed to sharing the road, and driven cyclists to seek out traffic training.
"I'm getting hammered by mayors asking, 'What are you doing about all these new bikers on the street and nobody knows the rules of the road?' " says Robert Raburn, executive director of the East Bay Bicycle Coalition in Oakland. When the organization started classes in 2003, it offered maybe two a year. Now, it has six slated for September with two more to be announced.
In the Bay State, MassBike reports offering two dozen classes this year, compared with three the year before.
The trend slips under the radar of national data, but phone calls to various city governments reveals a strong uptick in bike commuting this year:
• Bike count tallies showed an increase of 30 percent over last year on San Francisco's Market Street, 44 percent over 2006 levels at the intersection of Broad and Chestnut Streets in Philadelphia, and 378 percent from five years ago on Milwaukee Ave. in Chicago.
• New bikers are maxing out the capacity of transit systems across the country. Bikers boarding buses in Houston rose from 1,510 in April to 3,624 in June, according to the League of American Bicyclists, which also reports that Charlotte's bike-on-bus boardings have reached an all-time record, surging 30 percent this June from a year ago. On San Francisco's regional CalTrain, a quarter of rush hour trains surveyed in September "bumped" bikers because onboard racks had reached capacity.
• In Denver, this year's 'Bike to Work Day' drew 35,000 bikers, up 43 percent over last year.
High gas prices are changing transportation habits. For eight straight months, Americans have driven fewer miles than they did over the same period a year earlier, according to the US Department of Transportation.
"Biking kind of gives me a sense of independence. I'm not dependent on fossil fuels," says Margaret Chuang, another student in Mr. Hill's class.
But the rise, even if it's a small number, is affecting cities in everything from transportation funding to traffic safety.
Some cities are making substantial investments in bike infrastructure. The Bay Area's Metropolitan Transportation Commission (MTC) last month approved $1 billion in long-range funding for a regional bike network. Louisville is building a 100-mile hiking and biking trail called the Louisville Loop.
Congress, meanwhile, is considering a bike commuter act that would permit tax deductions like those for public transit riders.
Cities are also exploring ways to accommodate cyclist needs beyond pricey infrastructure upgrades. Some are painting "sharrows," a symbol on road surfaces, to remind drivers that cyclists are allowed on the road. "What we are really pushing for is more education both for cyclers and cars ...We have cyclists riding down wrong ways in bike lanes. And drivers not looking when they are turning or opening doors," says Kerri Richardson, spokeswoman for the Louisville mayor.
The MTC is also studying whether to adopt the so-called "Idaho stop" rule. This would allow cyclists to treat red lights like stop signs, and stop signs like yield signs. Idaho adopted these changes years ago, apparently with no incident. However, MTC'S proposal became an instant lightning rod, even in the bike-friendly Bay Area, tapping into driver frustration with cyclists who don't stop when expected.
Some cyclists avoid stopping fully because doing so means a loss of momentum that takes significant energy to regain, says Joel Fajans, a physics professor at the University of California Berkeley who has published research on bike propulsion.
"I'm in favor of this Idaho rolling stop rule because you don't have to come to a complete stop to be completely safe," he says. "On a bicycle ... you are only really endangering yourself when you speed through an intersection, while that's certainly not true when you are in a car."
Others in the bike community suggest the underlying problem is the proliferation of stop signs as a traffic calming measure.
A key precept in bike safety courses is the phrase: "Same roads, same rights, same rules." Hill's four-hour presentation highlighted common causes for collisions with cars and how to avoid them. It's partly a matter of proper bike positioning in a traffic lane to minimize driver error and partly cyclists following road rules and acting predictably.
Hill disagreed with one instructional video that seemed to sanction a cyclist turning left on a red light. "If we look at car-bike crashes and who's at fault, in a sense it doesn't matter," Hill said. The cyclist suffers either way.