Media playback is unsupported on your device Media caption Sharing the road

As American cities attempt to make their streets more bicycle friendly, some tensions arise between cyclists and motorists.

When New York City installed a bike lane next to Brooklyn's Prospect Park West, cyclists rejoiced.

The new lane was placed between parked cars and the pavement, providing them a safe place to cycle to and from work. It made it easier to circumvent the park, where cyclists heading towards Manhattan had to fight against the flow of bikes heading in the opposite direction.

The bike lanes were part of a larger city-wide initiative to increase bike access, one that found 66% support in the city.

Culture clash Across North America, growing pains as cities become more bike friendly Boston This September, the Boston Herald newspaper ran a string of articles on the city's "car-bike war" and "war of wheels"

This September, the Boston Herald newspaper ran a string of articles on the city's "car-bike war" and "war of wheels" New York City: In 2010, Hasidic residents of Brooklyn's Williamsburg neighbourhood successfully petitioned to have bike lanes removed, citing both the speed of cyclists through residential areas and the immodest dress of female cyclists

In 2010, Hasidic residents of Brooklyn's Williamsburg neighbourhood successfully petitioned to have bike lanes removed, citing both the speed of cyclists through residential areas and the immodest dress of female cyclists Seattle: Three cyclists killed in close succession have stirred a debate: some ask if the city is doing enough to make the city safe; some wonder if cyclists are being too reckless. In late September, the mayor called for a safety summit

But not everyone was happy with the change. Two groups - Seniors for Safety and Neighbors for Better Bike Lanes - sued to have the Prospect Park lanes removed.

They claimed that the city forced the lanes on residents, and that the bike lanes blocked traffic, created unsafe environments for pedestrians and were bad for commerce.

"While bike lanes are a terrific idea and they have a lot of recreational value, they're just not a reasonable alternative for the overwhelming number of city dwellers," says James Walden, an attorney representing the two groups.

A judge recently rejected a suit put forth by the group to remove the lanes. Walden and his clients have filed an appeal.

The lawsuit is an extreme example, but it's not an isolated one. As America becomes increasingly bike friendly, cities have had to find the best way to promote cycle-centric policies in a country where car is king.

Bikes on the rise

There's no denying that cycling popularity is on the rise in the US. Since 2001, the number of total bike trips has increased by more than 20%. While the levels of recreation bicycling trips remained steady, the share of bike trips taken for the purposes of commuting to work has increased by a third.

When we make improvements for bicyclists, often the biggest beneficiary are people who drive motor vehicles Mark Lear, Bureau of transportation traffic safety program manager, Portland, Oregon

That rise has been aided in part by conscious policy decisions designed to get more bikes on the road. These include additional bike parking, more bike-friendly public transit, and the expansion of bike lanes - often at the expense of available motorways.

"The whole point of these policies is to get people, to some extent, out of our cars and into transit, walking, or bicycling," says John Pucher, professor of urban planning and public policy at Rutgers University. "There's no way you're going to make car drivers happy with this sort of a policy."

Cyclists complain that drivers have showed their disdain in obvious, dangerous ways.

In Washington DC, the city council has introduced a bill allowing residents to sue those who intentionally harm or distract cyclists. The law came in response to a video showing a motorist intentionally hitting a cyclist in a DC neighbourhood.

But unhappy motorists - very few of whom are reckless - worry that new rules give special privileges to an elite few at the expense of the driving masses.

Safer streets

Research shows that infrastructure changes made to accommodate bicycles more often than not have the net effect of making the streets safer for everyone.

"This isn't a zero-sum game," says Janette Sadik-Khan, the commissioner of transportation for the city of New York. "You can make streets that work better for everyone. They can be safer for everyone, they can be more attractive. We can engineer a better environment for buses, a better environment for walking, and safer streets for driving."

In Portland, which has been a leader in promoting cycle-friendly streets, neighbourhoods have responded positively to changes made for cyclists. In large part, that's because the city works carefully to coordinate changes with communities.

People also respond well after seeing the changes take effect.

"Residents recognize that when we make improvements for bicyclists, often the biggest beneficiary are people who drive motor vehicles," says Mark Lear, Portland bureau of transportation traffic safety program manager.

That's in part because bicycle lanes force cars to slow down, which reduces both accidents and injuries. Because city driving is already punctuated by stop-and-start driving, dictated by stop lights and stop signs, a reasonable reduction of speed doesn't affect overall commute time or result in noticeable congestion.

But even Portland is not without its cycle cynics. Lear heard a complaint familiar to cities with cycling policies: namely, that cyclists were biking recklessly without being held to the same standard of accountability as cars.

In response, the city set up enforcement areas in places identified as frequent crash zones. Motorists, cyclists and pedestrians were ticketed for violations, and first time offenders were required to take a safety course.

"Anyone running a red light on a busy street is a risky thing," says Mr Lear. "We've gotten positive support both from people who have gone through the program and those who thought we were going about enforcement unevenly."

Inflated rhetoric

As cities adapt, its citizens react - but the issue is not nearly as polarizing as it seems.

"It's easy to find a quote from one side and a quote from the other and trump it up as a war," says Pete Stidman, the director of the Boston Cyclists Union. In reality, he said most people just want to work together to build a safer community.

The idea of "cyclist" versus "motorists" is shortsighted, says Gabe Klein, the commissioner of transportation for the city of Chicago.

"We have to get away from this idea that people are in just one camp - that they are only a biker or a driver or a transit user," he says.

Even the most bike-friendly European cities required years to move towards pedal-and-engine harmony. "It took four decades to transform Copenhagen," says Mr Pucher.