At 1 p.m. Monday, city work crews in San Francisco were striping the asphalt on Townsend Street for a new bike lane. An hour later, the first cyclists tried it out.

"There's been a lot of pent-up demand," said Renee Rivera, acting executive director of the San Francisco Bicycle Coalition.

The work on Townsend Street, between Fourth and Fifth streets, stretched less than half a block when it got its first riders.

But it carries the distinction of being the first bike lane painted in San Francisco after a Superior Court judge late Friday gave the city permission to fully implement its bike plan that had been held up by litigation for four years.

The city can now move ahead with plans to add 31 miles of new lanes to the 48 miles already striped.

The court intervened in response to a lawsuit filed by the Coalition for Adequate Review and Ninety-Nine Percent, which are led by blogger Rob Anderson. He demanded that before the bike enhancements proceed, the city conduct an environmental impact report to study, in particular, the effects of removing parking and traffic lanes to accommodate bike lanes.

The new lanes are likely to result in the removal of nearly 2,000 existing parking spaces. The city completed the court-ordered environmental review last year.

Judge Peter Busch partially lifted the injunction in November, allowing only projects that could easily be reversed to go forward. On Friday, he found the city in full compliance.

Anderson said Monday that he may appeal.

City officials, however, wasted little time getting started with the work.

"Today we are able to begin an earnest and aggressive bike plan implementation that will increase the amount of bike lanes by 64 percent," said Nathaniel Ford, executive director of the Municipal Transportation Agency, which oversees San Francisco's bike program.

The Townsend Street project, which when completed will run a little more than a mile between Eighth Street and the Embarcadero in the South of Market, will be followed by new lanes on Laguna Honda Boulevard and North Point Street.

In all, 60 projects are planned over the next five years at a cost of $12 million to $14 million, Ford said.

Aida Berkovitz, a retired traffic engineer for the federal government, rode her two-wheeler to the new (abbreviated) bike lane on Townsend Street just as the paint was drying. "I just wanted to check it out," she said. "This is exciting."

Berkovitz, who also owns a car, said she does most of her daytime travel in the city by bike. "I can get almost anywhere," she said.

In addition to new bike lanes, the city plans to install another 500 bike racks and 5,500 additional stencils on the pavement indicating which streets are designated bike routes. Plans also are in the works to start a pilot project allowing cyclists to bring folding bikes aboard Muni trains.

Mayor Gavin Newsom, who was joined by other elected and appointed officials at Monday's striping ceremony, said the city is committed to completing the planned projects without disruption.

"This is not the old days where it's about bikes versus cars," he said. "This is about bikes and cars. This is about quality of life."