On a blustery day this winter, ­Louise Hainline, a dean at Brooklyn College, stood on the roof deck of her Park Slope building, ­ankle-deep in fresh snow, squinting intently into the sun. Below, a lone cyclist coasted southwest along the iced edge of Prospect Park. Hainline shook her head. “And they say this bike lane gets a lot of traffic,” she scoffed.

Hainline, who is in her early sixties, has chin-length blonde hair, rounded features, and cheeks like burnished McIntosh apples. She and her husband, CUNY physics professor Micha Tomkiewicz, purchased their penthouse unit on Prospect Park West in 1997, â€œwhen real estate here was a little cheaper,â€ she says. There have been a lot of other changes to the landscape of Park Slope since they moved in. But in fourteen years, Louise Hainline has never seen anything as â€œmonstrousâ€â€”nothing as â€œtruly offensiveâ€â€”as the Prospect Park West bike lane.

To create the path, the Department of Transportation significantly rejiggered the swooping boulevard. Instead of three lanes of car traffic, Prospect Park West now has just two; the third has been converted into a bright-green two-way bike lane, installed this past June, that connects Grand Army Plaza with Bartel-Pritchard Square on the parkâ€™s southwest side. A barrier of parked cars protects bikes from passing driversâ€”who now have six fewer spots to fight overâ€”while an array of flashing lights and reflective signage helps modulate the new traffic patterns.

For New York cyclists, the Prospect Park West lane is the best of all possible worlds. For Hainline, it is an eyesore and an affront, and in recent months she has been agitating to have the lane removed. Her work is done under the auspices of Neighbors for Better Bike Lanes, an organization whose members include some of the most powerful residents of Park Slope, including Norman Steisel, a former deputy mayor and sanitation chief who feels the change was â€œjammed down our throats.â€ Among the groupâ€™s supporters is Iris Weinshall, Mayor Mike Bloombergâ€™s first transportation commissioner and the wife of Senator Chuck Schumer.

But it is to Hainline, a career academicâ€”her specialty is psychologyâ€”that much of the lobbying effort has fallen. Inside her apartment, Hainline maintains her de facto war room, a sun-soused office piled high with accident reports and petitions bearing the signatures of hundreds of like-minded Brooklynites. In October, she purchased an expensive spy camera; after attempts to film the lane from her own apartment ran into technical difficulties, she moved the rig to the house of a neighbor. A shiny MacBook Pro plays footage from the lane, and Hainline often sits in her office listening to her Pandora stations and counting the number of cyclists passing by with a handheld clicker.

Her central contention is that the Prospect Park West lane hasnâ€™t delivered nearly the advantages the Department of Transportation claims and cycling supporters too readily accept. â€œI do know, being a psychologist, that thereâ€™s this very strong phenomenon called confirmation bias,â€ she says. â€œWhen we hear story evidence, anecdotes, or even data, what we tend to rememberâ€”and this is an unfortunate human traitâ€”is the stuff we already believe anyway.â€

We walked next door to see the camera rig, Hainline now bundled up in a boxy barn coat. â€œIâ€™m not saying bikers are ignorant,â€ she said. â€œTheyâ€™re just holy. They really think theyâ€™re doing work for the environment if, instead of taking the car a block, they take the bike to go to the food co-op. Thatâ€™s touching, and itâ€™s in the right direction. But itâ€™s silly.â€

We arrived at a house belonging to Lois Carswell, another member of Neighbors for Better Bike Lanes and the founder of an allied group, Seniors for Safety. Carswell, an owlish, spunky woman in her seventies, met us at the door; her elderly schnauzer circled us warily. We walked up two flights of stairs and stopped in a carpeted bedroom facing the street. For a long quiet moment, the four of usâ€”me, Hainline, Carswell, the dogâ€”stood ogling the setup: the camera mounted on a tripod, a nest of wires piping the feed from the street to a hard drive from which Hainline retrieves video to review. It looked a little like the sort of apparatus once employed by the Stasi.

Together, the two have amassed what Hainline says is hundreds of hours of footage. That tape allegedly proves that the Department of Transportation has vastly overstated the benefits of the Prospect Park West bike lane by inflating its figures on how many people are using it. (The city says rider counts have nearly tripled to a thousand per weekday.) Furthermore, Hainline argues, the department had been â€œfudgingâ€ data that appeared to show a 16Â percent decrease in accidents.

Photo: Jamie Chung

Bike-lane supporters have countered that Hainlineâ€™s camera is set up on just one end of Prospect Park West and canâ€™t possibly account for all traffic. The matter will now have to be settled by attorneys. On March 7, Neighbors for Better Bike Lanes and Seniors for Safety filed a lawsuit against the DOT and Weinshallâ€™s successor, Commissioner Janette Sadik-Khan, seeking to have the Prospect Park West bike lane removed. The petition alleges that the DOT and pro-bike activists conspired to â€œsuppress criticismâ€ of the bike lane and asserts that the DOT relied on â€œmisleading, selective, and unsound data to support false conclusions.â€

â€œPeople feel there is a larger policy, which looks good on paper, and everyone can get behind in a general manner, but has been implemented in such a rash wayâ€”with not just a lack of information but misinformation being conveyed to communities,â€ says Jim Walden, a partner in the New York offices of topflight law firm Gibson Dunn, which has agreed to represent the anti-lane forces pro bono.

No matter that the Prospect Park West lane was officially approved by its community, with the project voted in first by the transportation committee of Community Board 6, which represents Park Slope, and then by the entire board. Walden maintains that the DOT set out to mislead residents from the get-go. â€œThis case is about a government agency wrongfully putting its thumb on the scale by fudging the data and colluding with lobbyists,â€ he says. Gibson Dunn is expected to bring its considerable resources to bear on the case, which could drag on for months.

“It’s not just a bike lane. It’s a repudiation of Iris Weinshall’s tenure as DOT commissioner. And it’s in her face every single day.”— Aaron Naparstek, Streetsblog

â€œWeâ€™ve never seen anything like this in the realm of neighborhood-level bike advocacy,â€ says Aaron Naparstek, creator of the pro-cycling site Â­Streetsblog and co-founder of the advocacy group Park Slope Neighbors. â€œItâ€™s crazy. Gibson Dunn is the law firm that represented George W. Bush in Bush v. Gore in 2000. Now theyâ€™re working to get rid of a bike lane. Think about that.â€

And so it has come to this: Bike lanes, not so long ago a symbol of a boldly progressive New York City, have sparked a bitter row on the hushed and leafy streets of brownstone Brooklynâ€”just one part of a biking backlash rippling across the five boroughs. Businesses citywide complain that by inconveniencing drivers, bike lanes hurt sales. At City Hall, a young Queens council member has floated the idea of requiring all adult cyclists to register with the city. Some Upper West Siders have jeered a new protected bike lane on Columbus Avenue. In Brooklyn, a proposed Lafayette Avenue lane in Fort Greene has been scrapped, perhaps indefinitely, joining a lane in South Williamsburg removed after protests from Hasidic residents upset by (among other things) female cyclistsâ€™ revealing outfits. On Staten Island, residents succeeded in reclaiming two lanes on Father Capodanno Boulevard, one of which has been converted into parking spaces.

â€œWe have entered a period where communities and community boards are very skeptical of the DOT,â€ says Robert Perris, the district manager of Community Board 2, which represents Fort Greene. â€œI hate to get philosophical, but these things sort of feed themselves. Thereâ€™s been lots of bad press about [bike lanes], and when people read some of those articles, it triggers a response of â€˜Yeah! I agree. Me too.â€™â€‰â€

New Yorkâ€™s bikers have been called renegades, menaces, and high-speed killers; opponents of bike lanes have been called troglodytes desperately clinging to an antiquated notion of city life. (â€œOppose bike lanes,â€ one Republican city lawmaker tells me, â€œand you get these people screaming that youâ€™re not fully evolved. That youâ€™re part of the â€˜old thinking.â€™â€‰â€) The bike-lane wars have become front-page fodder, grist for the international pressâ€”the Prospect Park West bike path, a Guardian blog recently opined, could â€œaffect the future of cycling worldwideâ€â€”and even a catalyst for an internecine spat between New Yorker writers John Cassidy and Hendrik Hertzberg. (Cassidy: â€œIf global warming disappeared tomorrow, the bike lobby would still Â­demand more bike lanes.â€ Hertzberg: â€œAnd I would be onboard with that, a hundred percent!â€) Bike lanes have even emerged as a wedge issue in mayoral politics. Congressman Anthony Weiner reportedly told Bloomberg that if he becomes mayor, he is â€œgoing to have a bunch of ribbon-Â­cuttings tearing out your fucking bike lanes.â€ Weiner later tweeted that the line was a joke, but you could see how a PG version might make for a good talking point in 2013.

As bike lanes have gone from simple strips of pavement festooned with green and white paint to sponges for a sea of latentÂ­ cultural and economic anxieties, their critics have come to include plenty of the usual suspects: The New York Post, which never misses a chance to fan the flames of populist ire, has for instance depicted the bike-lane rollout as an invasion of socialist-leaning, Eurocentric, limp-wristed Lycra warriors. Meanwhile, conservative outer-borough lawmakers have accused â€œChaka Khanâ€ and her DOT engineers of ignoring their constituentsâ€™ real needs. â€œIn my community,â€ says James S. Oddo, a City Council member from Staten Island, â€œbike lanes are a catchphrase for misplaced priorities.â€

Photo: Kathy Willens/AP Photo

In the prevailing spin, the bike-lane fight has two sides: the blue-collar New Yorkers who have to drive to work and the coddled creative-class types who live close enough to commute on their Bianchis. But the class dynamics are actually far more complicated, and the allegiances often defy expectations. The bike-lane opponent, for instance, is just as likely to be a well-to-do Manhattanite, and his main gripe the deliveryman who just pedaled the wrong way down a freshly laid bike lane, in a rush to unload a wood-oven pizza (which, on another day, that Manhattanite himself might have ordered). Simple nimbyism canâ€™t entirely account for the feud in Park Slope, home to Paul Steely White, executive director of the cycling and mass-transit advocacyÂ­ group Transportation Alternatives, as well as pro-bikers like Naparstek and his Park Slope Neighbors co-founder Eric McClure. Meanwhile, Hainline, a Brown and Harvard grad worried about global warming, considers herself a progressive. The battle lines blur until it becomes almost impossible to guess which side someoneâ€™s going to come down on. â€œ[The cyclists] think that weâ€™re a bunch of old, crotchety rich people that donâ€™t understand that they deserve to have a bike lane on our street,â€ says Hainline. â€œThatâ€™s not it at all.â€

One thing that does seem to unite bike-lane opponents is an accrued resentment toward nine years of Bloombergian smoking bans and nutrition-labeling and all-around overreach. The most important common denominator, though, may be a strong preference for the city that was over the city that may be. In his long New Yorker harangue, John Cassidy recounts the cars he has owned since moving to New York: a Thunderbird, a Mercedes 190E, an Oldsmobile Delta 88, two Cadillac Sedan DeVilles, and a Jaguar XJ6. Itâ€™s not for nothing that these can be considered nostalgic models, meant to signify that their driver is of the old school.

To critics like Cassidy, bikesâ€”the older, cheaper technologyâ€”are the privileged interlopers, and bikers are a â€œsmall faddist minorityâ€ bent on changing New York into something itâ€™s not meant to become (not to mention making it harder for him to park). â€œWe will never be Amsterdam, never be Copenhagen,â€ says Hainline. â€œWe are never going to be Portland.â€ The thing about how cities work is that just by saying those kinds of things often enough, opponents have a way of making it so.

We have been through all of this before. In 1980, Mayor Ed Koch took a trip to Beijing, a city thick with cyclists, and returned to New York â€œswept away by the thought of what could be.â€ Over the next year, his administration spent $300,000 creating a pair of six-foot-wide bike lanes, which rolled south from the lip of Central Park and into the heart of the Village. The timing was propitious. As one columnist noted at the time, â€œthe bicycle, formerly a Christmas-tree item or a Sunday diversion, has become a serious vehicle of transport in some American cities.â€ An early survey conducted by transportation officials showed that 3,000 cyclists a day were utilizing the path on Sixth Avenue.

“Bikers really think they’re doing work for the environment if, instead of taking the car a block, they take the bike to the food co-op. That’s touching. But it’s silly.”— Louise Hainline, Neighbors for Better Bike Lanes

It didnâ€™t take long for the cracks to appear. Workers in midtown wandered bleary-eyed into oncoming cyclists and walked away with fodder for furious letters to their congressmen. Governor Hugh Carey jeered that Koch had a â€œfetishâ€ for bikes. Trash began to accumulate in the bike lanes (as it does today). Business associations lobbied for their removal (as they do today). Four months later, the city announced it would pave over the lanes. A group of protesters smeared themselves with fake bloodâ€”it was ketchupâ€”and attempted to lie down in front of the oncoming bulldozers; Koch went through with the demolition anyway.

For cycling advocates, the defeat was a lesson, proof that they would have to fight harder, organize more effectively. By the mid-aughts, a vibrant lobby of pro-bike groups was proposing additions or alterations to city streets. Those groups, in turn, were supported by sites like Naparstekâ€™s Streetsblog and by the members of the Critical Mass movement, who were already notorious for jamming streets with bikes to draw attention to cyclistsâ€™ rights. â€œItâ€™s like Martin Luther King said in his letter from the Birmingham jail: You have this creative tension thatâ€™s created where you have people working the direct-action angle, as well as people doing the boardroom stuff,â€ says CUNY professor Benjamin Shepard, a longtime Critical Mass supporter. â€œThatâ€™s where the real power came from.â€

Others have argued that the groupâ€™s pugnacious tactics mostly helped further unhelpful stereotypes about city cyclists. With few bike lanes to draw out everyday two-wheeled commuters, for a long time about the only people you saw on bikes in New York were messengers, deliverymen, and extreme hobbyists. Biking in New York was for the reckless; it was not, as it is in the rest of the country, something done by a cute kid on a Huffy. (The activists these days eschew the tactics of yore. Pro-biking posters now pointedly feature children and families.)

When Sadik-Khan was tapped as DOT commissioner, in 2007, cycling activists finally gained a long-awaited ally. Â­Unlike Koch, who backed off the bike-lane push when the fire got too hot, or her predecessor, Iris Weinshall, Sadik-Khan Â­relentlessly pursued a pro-bike agenda. She spoke regularly of the importance of the â€œcomplete streetâ€â€”a street, in other words, that belonged to more than just cars. â€œIâ€™m pro all modes of transportation, not one mode elevated above all others, which I think has been the case in the past,â€ Sadik-Khan has said. â€œWeâ€™re really just trying to rebalance our system, bring some acupuncture to what has been a sick body.â€

Under Sadik-Khanâ€™s supervision, the DOT has laid down an unprecedented 255 miles of bike lanes all over the city, with more in the pipeline for this year. Judged purely on the goal of creating more bike riders, the lanes have been a success. The DOT estimates that twice as many New Yorkers rode their bikes to work in 2010 than in 2006, while the number of New Yorkers who ride their bike daily has increased by 13 percent in the past year.

But that still adds up to just 216,000 cyclists on the street on any given day, according to Transportation Alternatives, and they remain vastly outnumbered by cars. To make significant room for bikes must thus be seen as a prescriptive move: an attempt to wean us off our dependence on two-ton hulks of pollution-spewing metal. An invitation to envisage a different, cleaner, healthier New York. Which of course also makes it a political act, and itâ€™s the politics that seem to have caught Sadik-Khan unawares.

Bike lanes are relatively easy to install. The Prospect Park West path, with all its safety paraphernalia, was built in about a month; unprotected lanes can be created in a matter of days. Bike lanes are also inexpensive. The Bloomberg administration estimates that over the past four years, the city has spent $11 million installing bike lanes, with two thirds of that cash provided by the federal government. Over the same period, the city spent $1.5 billion on street repair alone. And since streets with protected bike lanes see 40 percent fewer accidents, according to City Hall, and traffic crashes set the city back over $4 billion a year, bike lanes can actually save New York money. They also cut pollution, which is good for everyone. Bike lanes, when framed this way, are just common sense.

“Cyclists can be anywhere, at any time. You have no peace. It is homegrown terrorism.” — Former Bike-Store Owner Jack Brown

But from the beginning, Sadik-Khan has had a tendency to communicate her vision for a bike-friendly New York in much grander terms, which has only made her vision easier to attack. In a profile in this magazine in 2009, she said she often looked abroad for inspirationâ€”â€œI basically go around the world borrowing ideas from other placesâ€â€”feeding charges that she was out of touch with the average New Yorker. â€œMost people in New York,â€ says Jimmy Vacca, a Democratic council member from the Bronx, â€œwill never ride a bike to work. They will never ride a bike to a show. Not going to happen. Period.â€

Sadik-Khan took office in May 2007, not long after the city unveiled a sweeping sustainability initiative called PlaNYC. By June, the DOT had installed a handful of new lanes, including two in Manhattan; by 2008, the agency was reporting that cycling was up 35 percent citywide. But by then, the Post had already fired its first shot: â€œWheelie Angry Over Bike Lane; Chelsea Peddlers Take on Pedalers,â€ ran the headline. In 2009, mayoral hopeful Bill Thompson made bike-lane review a component of his electoral platform. Critical lawmakers, with further assists from the Post and indefatigable CBS2 reporter Marcia Kramer, continued to lash out at the DOT for its perceived tone-deafness throughout the next year.

Bike-lane opponents are now hoping that the Prospect Park West bike lane could be the place where (Cassidy, again) the â€œunstoppable forceâ€ of Sadik-Khan meets an â€œimmovable object.â€ The immovable object in this case is Iris Weinshall. The knock on the former transportation commissioner among cycling advocates was that her support for their cause always seemed halfhearted. Her backers would say she was just heeding the popular will. â€œClearly, if the lawsuit was to succeed, [Weinshall] could say, â€˜See, I was reasonable after all,â€™â€‰â€ says Andrew Vesselinovitch, who served as the New York City â€œbike czarâ€ under Weinshall before leaving the DOT in protest in 2006. To Weinshallâ€™s critics, she is waging a personal vendetta. â€œItâ€™s not just a bike lane. Itâ€™s a repudiation of her tenure as DOT commissioner. And itâ€™s in her face every day,â€ says Naparstek.

When I approached Weinshall at a Â­community-board meeting in January, she said only that she thought the DOT had gone about the Prospect Park West lane the wrong way; later, I spoke with her at length over the phone, but she ultimately declined to go on record. Finally, I received a call from Dov Hikind, a New York State assemblyman who represents the 48th District, in Brooklyn, saying he was contacting me on Weinshallâ€™s behalf. â€œI can get to God faster than I can get to her,â€ he said of Sadik-Khan. â€œListen, the commissioner enjoys having the freedom she has. At night she dreams of these things, and the next day she does them,â€ Hikind said. He wanted me to know that he was particularly vexed about a set of pedestrian islands on Fort Hamilton Parkway, in Borough Park. He said heâ€™s exploring a lawsuit against the DOT if the pedestrian islands are not removed.

Supporters of Weinshall have insisted that the Prospect Park West suit is not an effort by Weinshall to take the shine off the accomplishments of her successor. They also deny that Neighbors for Better Bike Lanes is using her political connections in its bid to get the lanes removed. But thatâ€™s done little to quell the pro-bike forces, who have taken to pointing out that Gibson Dunn lawyer Jim Walden made the maximum contribution to Weinshallâ€™s husband, Chuck Schumer, in 2010. â€œOnly the radical bike-lane folks are using their political juice here,â€ Walden says. â€œThey have had DOT in their hip pocket from day one, and the louder they crow about one of my many political contributions, the more you know they are desperate to drown out the voices now calling for an investigation into their misconduct with DOT.â€

As the bike-lane fight (and the stakes) escalates, Mayor Bloomberg continues to support Sadik-Khan, at least publicly. â€œJanette is doing exactly what the mayor expects of all his commissioners: pioneering innovative new ways of serving the public, no matter what the politics,â€ says Frank Barry, the director of public affairs at City Hall. â€œThere will always be some who resist change, but in the case of bike lanes, the community boards have strongly supported themâ€”and the safety numbers show theyâ€™re saving lives.â€ In 2008, the city says, 26 people died in bike-related accidents in New York. Last year, the number was eighteen. The number of pedestrian injuries citywide is shrinking. In several categories, New York ranks as one of the safest cities in the country. Plus the Bloomberg administration is not one to allow itself to be bullied. â€œIf you let the threat of a single lawsuit paralyze you, youâ€™d never get anything done,â€ says Deputy Mayor Howard Wolfson.

â€œVery little has changed on our streets in 50 years,â€ Sadik-Khan tells me. â€œThey need to be updated to reflect who uses them and how theyâ€™re used. We must balance the needs of drivers, bus riders, pedestrians, and cyclists so all of them get around safely and efficiently.â€ Friends say that Sadik-Khan has managed to keep her bearings largely because she remains convinced of the long-term necessity of a citywide cycling infrastructure. â€œI know itâ€™s difficult to take the kind of opposition that sheâ€™s facing right now,â€ says Steve Hindy, the co-founder of Brooklyn Brewery and a Transportation Alternatives board member. â€œBut Janette is a really tough lady.â€

“You can talk about the reduction in crashes, the reduction in car speeds—but that is so disconnected from people’s panic over change.”— Caroline Samponaro,Transportation Alternatives

Oddo, the Staten Island councilman, says that in recent weeks, the commissioner has made an effort to meet with disgruntled council members. But he also believes the lack of outreach in the early going badly hurt the bike-lane push. â€œIâ€™m telling you, you could hand out apple pie for free all day long,â€ he says, â€œbut if you hand it out with an imperial attitude, no one is going to take it.â€

In late January, I spent an hour biking around Manhattan with Caroline Samponaro, the 32-year-old director of bicycle advocacy at Transportation Alternatives. I had asked her if she would show me a DOT project that she viewed as a success, and sheâ€™d suggested the Ninth Avenue bike lane. The project was met with fierce opposition when it was first implemented in 2007, but at some point, Samponaro remembers, tempers died down and the conversation became less of a â€œyes-or-no thing and more about modifications to the lane, tailoring the path so it was better for everyone.â€ She says she expects something similar to happen citywide. â€œYou can talk about the reduction in crashes, the reduction in car speedsâ€”but that is so disconnected from peopleâ€™s panic over change,â€ she says. â€œThis is the teething period.â€

The Ninth Avenue lane is protected and wide. It has one set of lights for cars and another for bikes, which radically decreases the chance that a car can cut left across the bike lane and into a cyclist. But even these amenities offer no perfect dam. At the next light, Samponaro and I watched as a cab barreled over the median and fishtailed back into the flow of traffic. â€œWell, that just happened,â€ Samponaro deadpanned, using a black Kombi mitt to brush a curl of hair out of her eye.

Still, the Ninth Avenue lane is an ideal place to experience the unfettered freedom that can come with riding a bike in New York. As any urban rider (and I am one of them) can attest, there is something infinitely joyful in putting foot to pedal, something intoxicating in not being bound by the whims of a bus driver or subway conductor or thick tangles of crosstown traffic. Whipping down the street, completely protected from the cars zooming by just a few feet away, may be the closest any New Yorker comes to flying.

Itâ€™s a wonderful feeling, this freedom. But freedom in New York does not belong just to the cyclist. Driving in midtown may be less than exhilarating, but we nonetheless want the freedom to drive there. Tellingly, the death knell for the old Koch lanes was tests showing that a 29-block stretch of northbound car traffic had been slowed by between five and ten minutesâ€”actually a sign that the bike lane was doing its job, since one benefit of bike lanes is a calmer street, but a damning finding in this always-in-a-hurry city. Ditto for Prospect Park West: Traffic speeds are down, which has pleased pedestrians and cyclists and infuriated drivers.

Drivers, of course, are used to operating within given constraints and might eventually come around to coexisting with bike lanes. Pedestriansâ€”who have had the most visceral reactions to bike lanesâ€”are another matter entirely. In New York, aggressive walking is a point of pride. We walk with lights and against lights, but mostly we walk fast; the sidewalks, which lack the amenity of passing lanes, play host to their own version of tailgaters and reckless mergers. When, in February, The Wall Street Journal ran an article on the phenomenon of â€œsidewalk rage,â€ it was akin to releasing scientific proof that our buildings are tall.

The New York pedestrian gets good at judging his or her foot speed against the velocity of onrushing vehicles. But the addition of bike lanes, and the bikers they carry, has made jaywalking a more fraught proposition. â€œYou know about the cars. You know about that potential danger when youâ€™re crossing the street. You know you might end up a bag of blood and guts and bones. But that is a finite realm of danger,â€ says Jack Brown, who used to own a bike shop in the East Village. â€œWhen it comes to cyclists, that danger is infinite. Cyclists can be anywhere, at any time: on the sidewalk, riding the wrong way down the street. And you have no peace â€¦ The anarchy that has been allowed to prevail is astonishing. According to butterfly theory, according to chaos theory, I am sure that the level of emotional and psychological damage wrought by the bicycle far exceeds the damage done by cars.â€ And then Brown goes there: â€œIt is homegrown terrorism. The cumulative effect is equivalent to what happened on 9/11.â€

“This is being jammed down our throats.”— Former Deputy MayorNorman Steisel

Four years ago, bike lanes seemed like an elegant solution to New Yorkâ€™s ticking population time bomb. By 2030, the population of the city is expected to reach 9.1 million. There is absolutely no way all of those bodies are going to fit into the overcrowded, drastically underfunded subways and buses; if more opt to drive, the gridlock could be nightmarish. Why not give people the option to climb on their bikes? Why not offer them protected lanes and slower streets and flashing lights and reflective signs?

And yet, as we are all becoming increasingly aware, in crowded New York, space, and convenience, is finite. Any alteration is an exercise in redistributionâ€”to give to Column A, you have to take away from Column B. Because the streets and sidewalks represent 80 percent of the public space in this dense city, they are far from mere utilitarian corridors. They are our shared front yard, turf to be guarded against any use that comes at our expense. In certain cases, such as in Park Slope, the street is not just a street but â€œa grand boulevard,â€ and its aesthetics are so perfect that any change can be seen as intolerable.

The hyperbolic excesses of partisans like Brownâ€”and, to a lesser extent, Neighbors for Better Bike Lanesâ€”are absurd, of course. But they do serve to highlight the inherent problem with bike lanes: Every time we add a bike lane, an adjustment has to take place, the â€œbutterfly theoryâ€ of Brownâ€™s tirade. The DOT can put in bike lanes by the thousands, but the more important transformation will be internal: We are going to have to learn to accept a decrease, however minuscule, in our individual freedoms. For bike lanes to really work, New Yorkers are going to have to learn to share.

Sharing, however, will first require a commitment by all New Yorkersâ€”and especially bikersâ€”to abide by the rules of the road. â€œIf youâ€™re going to put more cyclists on the street, you have to make sure thereâ€™s more enforcement,â€ says Nancy Gruskin, a music teacher and activist based in New Jersey. And until recently, that hadnâ€™t happened. â€œIt feels very haphazard: You throw something out there and expect that the structure is going to build itself, and what happens is that you have civil war.â€

In 2009, Gruskinâ€™s husband, Stuart, was struck and killed by a bicycle deliveryman riding the wrong way down 43rd Street. Gruskin later settled with Call Cuisine Caterers, the company that employed the deliveryman; a year later, she started a foundation dedicated to â€œdeveloping safety awareness for pedestrians in urban areas.â€Her newest initiative, called Pedal Pledge, asks business owners to insist that their deliverymen follow a basic set of traffic laws. So far, more than 40 have signed up, Gruskin says.

The city, for its part, has of late taken steps toward keeping order on the streets. In February, Bloomberg signed into law a bill that mandates the collection of data on bicycle-on-pedestrian collisions. And City Hall spokesperson Frank Barry says the NYPD is â€œdoing more to ticket those who donâ€™t follow the rules of the road.â€ Barry adds that â€œat the same time, weâ€™re expanding our public-education efforts so cyclistsâ€™ expectations change about whatâ€™s appropriate. Just as itâ€™s become socially unacceptable to light up a cigarette in a restaurant, weâ€™re working to make it socially unacceptable to bike against traffic or blow through red lights.â€ He pointed specifically to the â€œDonâ€™t Be a Jerkâ€ ad campaign, which will target unruly cyclists; where the PSAs donâ€™t work, the city is betting that the $200 fines cops are now issuing en masse will.

Some advocates see true acceptance of bike lanes as arriving with â€œbike shareâ€â€”a system, like ones already in use in Europe, where riders can rent bicycles from automated stations citywide. Transportation Alternatives is pushing for such a program in NYC; the DOT has solicited proposals from independent contractors. â€œOnce [bike share] is in play, and the bikes are everywhere, I think thatâ€™s when people really get involved,â€ Samponaro says. Mark Gorton, an investment-firm executive who founded the controversial and now shuttered file-sharing service LimeWire and has been a big donor to transportation-reform groups, agrees that bike share would helpâ€”but says that a more comprehensive network of lanes is even more crucial. â€œI hear a lot about how all these bike lanes are empty,â€ Gorton says. â€œAnd on some level, itâ€™s true: The lanes are empty because people like us ride on them, but for other people, itâ€™s too disconnected of an experience. Itâ€™s dangerous and hard to get from one lane to the next.â€

“If you let the threat of a single lawsuit paralyze you, you’d never get anything done.” — Deputy Mayor Howard Wolfson

Even opponents such as Norman Steisel concede that the further bike-ification of New York is probably inevitable. But smoothing that process will require some fundamental shifts on all sides. â€œMayoral agencies could do a better job with speaking with community boards, earlier and at more depth,â€ says Community Board 2â€™s Robert Perris. â€œCommunity boards could be more open-minded and less prone to nimby responses. And bike riders need to understand that as the New York transportation paradigm gets changed, they need to find a graciousness about this, if only for their own self-interest.â€

For now, the Park Slope lawsuit promises to keep all parties in a fighting stance. In early March, a few hundred residents of that neighborhood crowded into the auditorium of John Jay High School, a hulking structure on Seventh Avenue. The meeting had originally been convened by Community Board 6 to discuss minor alterations to the fabric of the Prospect Park West lane, but news of the lawsuit had broken earlier that week, and it quickly became clear that everyone in the auditorium, including the members of the community board, intended to use the occasion to air their personal views on the very existence of the path. One reporter accurately described the revised agenda as a â€œlane-themed open-mike night.â€

In January, at another of these community meetings, I had watched a throng of women, red-faced and nearly apoplectic, bend forward at the waist and shake their fingers at a hapless DOT engineer, like a chorus of distaff Joe Wilsons. â€œYou lie!â€ one of the women hooted. On this night the mood in the sweltering auditorium quickly grew similarly restive. In the hallway, a small army of sweaty reporters wrestled for a chance to get face time with the most obstreperous of the partisans; a pair of cops waited nearby. At one point, Lois Carswell, of Seniors for Safety, was cornered by an enraged mother, who shouted at Carswell until she turned an angry shade of lavender. Jim Walden, in clear view of the cameras, clamped his hands solicitously on Â­Carswellâ€™s shoulders and asked, â€œLois! Lois, are you all right?â€ (She was.)

The first speaker of the night was a child. She appeared to be wearing pajamas. Her name was June, and she was 7 years old. June thanked the Department of Transportation for the bike lanes and then went home to go to bed. Another child was produced and ushered to the front of the stage; he was equally adorable. Finally the baton was passed to Â­Louise Hainline, who mumbled something about having a hard act to follow.

â€œThere has been a tremendous and unfortunate amount of vitriol and name calling,â€ she told the crowd. â€œSome of you demonized us. Some of you have called us nasty names. We are not your enemy.â€ A couple of jeers bounced off the high ceilings of the auditorium. Hainline grew flushed. â€œWe canâ€™t keep this up,â€ she said. â€œWeâ€™re going to get tired. Youâ€™re going to get tired. We need to take a deep breath.â€

Before that night, the members of Neighbors for Better Bike Lanes had been insisting on the complete removal of the Prospect Park West lane. But now, as the audience looked on in befuddlement, Hainline offered a compromise. Her group, she said, would be willing to accept a single unprotected bike lane, along with a two-way bike lane in the park. â€œWe will move the cars back to the curb,â€ Hainline said. She said something else, too, but by then the auditorium had erupted in boos and cries of â€œSit down!â€ and her voice was drowned out completely.