PORTLAND, Oregon (Reuters) - As high gas prices force U.S. drivers to share city streets with a growing legion of cyclists, tensions are mounting between the two groups who blame each other for failing to find a peaceful balance.
A number of violent confrontations in recent weeks between cyclists and drivers have weighed on Portland's reputation as America's most bike-friendly city, while accidents and "road rage" incidents are prompting other cities to try and make the roads safer for bikes and ease the hostility.
In mid-July, an angry driver chased down a Portland cyclist and carried him for several blocks on the car's hood. Before that, a cyclist, upset at a driver who yelled at him for riding through a stop sign, threw his bike at the car and then attacked the driver.
"We are seeing more bicyclists on the road because of the price of gas and we see more of these" problems, said Marni Ratzel, a bicycle/pedestrian transportation planner in Boulder, Colorado, which has more than 300 miles of city road outfitted with bike lanes.
In Louisville, Kentucky, the number of cyclists have doubled or tripled since last year, based on the estimates of Dirk Gowin, the city's transportation planning administrator.
"Education is the real issue," said Gowin. "We have bicyclists riding against traffic, on the sidewalk and without helmets. They don't know what they are doing."
A common complaint from motorists is that cyclists don't obey traffic laws and ride recklessly, while cyclists charge that motorists don't watch out or yield to them when required.
A protest by cyclists in Seattle turned violent this month when a motorist struck several riders blocking the road. A few riders, according to Seattle police, engulfed the car, broke its windshield, slashed its tires and assaulted the driver.
Most cyclists are undeterred by these incidents since most trips are safe and uneventful. Biking to work, cyclists say, has both health and environmental benefits.
"Since 1990 a lot of work has happened. The facilities are there in many cities," said Elizabeth Preston, director of communications for the League of American Bicyclists.
Pedal pushers are still a tiny minority in the United States. Only 0.4 percent of Americans bike to work, compared with 2.5 percent who walk and 77 percent who drive alone, according to 2005 U.S. Census statistics.
In Portland, where 6 percent of people bike daily, workers commute and parents tuck kids into bike trailers and haul them to school or play dates. Bike riders pedal to the video store, grocery and restaurants.
"It used to be you'd see three bikes at a traffic light, now you see 12," said Dave Pearson, a bike commuter for 15 years who pedals 15 miles each way to his office at Nike two or three days a week.
Portland had six cyclists killed in accidents last year.
Local officials are taking many steps to make the city safer for both cyclists and drivers.
As part of a two-day "education mission" in July, Portland police targeted two heavily trafficked bicycle routes, blitzing bicyclists and motorists with warnings when traffic laws were violated.
Of the 128 warnings, 113 went to bicyclists. More such enforcement actions are planned, Brian Schmautz, Portland Police Bureau spokesman said.
The city, which already has 170 miles of bike lanes, is experimenting with bike boxes, or large painted areas at the front of an intersection allowing bikes to move to the front and stop at a light in front of cars.
The bike boxes are designed to end the dreaded "right hook" when a bicyclist is traveling straight and is cut off by a car turning right.
More accidents are part of the growing pains of an increase in bike commuting, but the situation will improve as ridership grows, according to bicycle advocates.
"The data shows that as more people ride, the streets get safer," said Scott Bricker executive director of Portland's Bicycle Transportation Alliance.
Editing by Daisuke Wakabayashi and Philip Barbara