Attending the Copenhagen climate conference last December, Mayor Antonio Villaraigosa of Los Angeles had a revelation: his own city needed to do more to promote bicycling as a clean form of transportation.

“I’ll tell you what I came away with: that in the area of bicycling, I’ve got to do a better job and the city’s got to do a better job,” Mr. Villaraigosa told Southern California Public Radio.

Last weekend, however, the mayor learned a tough lesson about urban cycling firsthand: cars and bikes don’t mix.

On Saturday evening, Mr. Villaraigosa hopped on a bike for a quick ride down to the beach. While he was riding in the bike lane on Venice Boulevard, a taxi abruptly pulled out in front of him. He swerved, fell off the bike and broke his elbow.

The incident was a gift to the cycling bloggers of Los Angeles, who have long complained about drivers who fail to respect bicycle lanes and a general lack of enforcement of safety laws by the police.

“He’s now officially one of us,” wrote Ted Rogers of the blog Biking in L.A. “Welcome to our world.”

In an essay on The Huffington Post, Mr. Villaraigosa reflected on his accident and promised to increase efforts to make the city more bike-friendly.

“If there’s one thing everyone now knows after my recent accident, it’s that I like to bike in Los Angeles,” he wrote. “The city’s landscape, climate and neighborhoods offer a cyclist’s paradise. Biking in Los Angeles should be a natural.”

“Unfortunately most of our city was built with cars in mind,” he added. “It’s time to recognize that bicycles also belong on L.A.’s streets.”

The mayor pledged to improve the city’s bicycle infrastructure and to step up enforcement of traffic laws. The city plans to set aside 10 percent of the revenue from a new sales tax levy – about $3.2 million this year – for bicycle and pedestrian improvements.

Also in the works is a citywide network of bikeways for commuters. “Eventually we plan to build a network of 1,663 miles of bikeways,” Mr. Villaraigosa wrote.

And despite his accident, he promised to keep on riding.

“I will be back on my bike as soon as I’m able, and I hope to see more Angelenos out there with me,” he wrote.