On a cool, sunny morning in Brooklyn, rush hour on Prospect Park West can look like the apple of a traffic engineer's eye. Streams of cars ease off Grand Army Plaza, stop at a light at Carroll Street, and move smoothly on, mostly undeterred by even the occasional double-parked school bus. Pedestrians leaving luxury apartment buildings head north to the nearest subway stop. And, along the street's eastern edge, there is its most controversial feature: the two-way bike lane installed almost a year ago.

Riding there, on one such morning, were women with messenger bags, men in business clothes, children with school backpacks. A small boy rode by on training wheels. A father on one bike had a daughter sitting behind him and another riding a scooter alongside. The lane was, at first glance, an unlikely source of controversy at all. Successful by all reported statistical measures, it is the result of a years-long governmental outreach process, popular with the local community board and in its neighborhood, Park Slope, as a whole.

The lane's short history has been troubled, though, in large part because of a few of its high-profile neighbors. They include Borough President Marty Markowitz, Dinkins-era deputy mayor Norman Steisel, and Louise Hainline, a Brooklyn College dean who lives in a Prospect Park West penthouse and monitors the lane from a spy camera. No lane opponents have raised more eyebrows in city political circles, though, than Iris Weinshall – a Prospect Park West resident, a former city transportation commissioner, and the wife of Charles Schumer, one of the most powerful politicians in the country.

Weinshall, who is now a vice chancellor at the City University of New York, responsible for facilities planning and construction, has kept a low profile on the bike lane issue lately. She did not respond to a call or an emailed list of questions for this article, and the nuances of her current thinking are hard to know. But her close association with a group that is suing the city over the lane, and her few public statements on the project, all of which were negative, have given the lane opposition one of its most important allies.

In December, City Council member Brad Lander told The New York Times that Weinshall and Steisel had met with him to advocate tearing the Prospect Park West lane out. And along with Steisel and Hainline, Weinshall signed a letter to the paper that month that cast doubt on the DOT's statistics that showed the lane was working. The letter accused the department of a "lack of credibility," and, although Weinshall and the other two authors said they support bike riding in principle, they also suggested that it should require a special license.

A note accompanying the letter identified the authors as members of Neighbors for Better Bike Lanes – the group that, along with an organization calling itself Seniors for Safety, is behind a lawsuit seeking the lane's removal. The suit's first hearing in court is scheduled for June.

In recent months, the lawyer representing the bike lane opponents has said Weinshall is not a party to the suit. And Hainline, one of the letter's other two authors, said in a short recent phone conversation that questions about Weinshall are misdirected. "The bike lane issue on Prospect Park West is about anything else except Iris Weinshall," she said. "She's not the people who are centrally involved in this. It's a gossip story."

Weinshall's advocacy, though, goes back further. The Daily News reported last July that she had attended a strategy session against the lane, and the Post said in February that Schumer himself had lobbied against it in private conversations with City Council members. In October 2009, in a letter obtained by the transportation advocacy site Streetsblog, Markowitz wrote the DOT a letter opposing the lane, noting pointedly that he was "joined in this request by former DOT commissioner Iris Weinshall, who absolutely agrees that the installation of a two-way, barricaded bike lane would cause incredible congestion."