If you ever needed a sign the mean streets of New York are changing, this is it: Mayor Bloomberg's new transportation commissioner bicycling to work through the West Village.Janette Sadik-Khan pedaled to her Church St. office last month on the second day of her term in charge of the often traffic-clogged streets and pedestrian-jammed sidewalks.Her appointment - and Bloomberg's plan to reduce traffic and pollution partly by charging a fee to drive into much of Manhattan - marks "a new era for New York City streets," said Paul Steely White, executive director of Transportation Alternatives. "The streets are not just for driving but can be redesigned for the majority, who don't drive."His enthusiasm was more than matched on Streetsblog.com, where a photo of the bicycling commissioner, provided by the Department of Transportation press office, was posted not long after the journey ended."New DOT commish is [a] biker," one writer gushed. "This is awesome."Sadik-Khan, 47, was born in San Francisco but has spent most of her years in the tristate area, and considers herself a New Yorker.Her father is an investment banker, and her mother is a journalist-author who once covered City Hall. After graduating from Occidental College with a degree in political science, she worked on children's health and welfare issues with the Children's Defense Fund in Washington.She earned a law degree, worked briefly for a private law firm and then took her first of a series of transportation-related positions at the city and federal levels.Her most recent job was in the private sector as senior vice president of Parsons Brinckerhoff, an international consulting and engineering firm.With Parsons, she once spent three months on the road with her husband and young son Max, exploring different national parks while developing a transportation planning guide for the National Park Service.Sadik-Khan, who plans to bike to work once a week, said a major goal was to "green-up" the DOT. That means placing a strong emphasis on making the city more friendly for cyclists and pedestrians, with such things as more bicycle lanes and places for cyclists to store their bicycles while working.