SAN FRANCISCO — The bicyclist was zipping south on Castro Street at the end of his twice-weekly ride to the Marin Headlands, blowing through red lights and stop signs.

But the Market Street crosswalk was filled with pedestrians, and Chris Bucchere, 36, allegedly was riding too fast to stop. So he aimed for the least populated spot and plowed on through.

“In a nutshell, blammo,” a blogger purporting to be Bucchere wrote that March day. The man he hit, Sutchi Hui, 71, died four days later. Bucchere was charged Thursday with felony vehicular manslaughter and is scheduled to be arraigned next week.

Post-crash commentary, angry and profane, didn’t just call for Bucchere’s head, although there was plenty of condemnation for him and the rest of the Lycra-and-toe-clips set. Instead, the conversation became a fight about who owns public space — a scarce resource in the second-most dense city in America, where bike use is soaring and many motorists decry a war on cars.

In the ongoing smart-growth discussion, San Francisco offers a cautionary tale for cities where officials are mulling antidotes to sprawl and working toward less dependence on the private auto.

Two-wheel travel has grown 71% in the last five years here, and officials have passed ambitious new goals: 50% of all travel within the city limits should be by something other than a private vehicle by 2018, and 20% should be via bike by 2020.

But even in this environmentally correct city — where the San Francisco Bicycle Coalition wields great clout and 10 of 11 supervisors joined the mayor in pedaling to the Civic Center on Bike-to-Work Day — the transition has been rocky.

“There’s a thinking now that the public realm should be for people to be in, not just to drive through,” said Ed Reiskin, San Francisco’s director of transportation. “But as cycling has increased and our infrastructure has not kept up, there are conflicts and tensions. …I’m no cyclist hater. But there’s a lot of bad behavior out there.”

Exhibit A: The death of Hui, the second pedestrian killed by a bicycle rider in downtown San Francisco in less than a year.

“Mr. Hui was in the crosswalk legally,” Dist. Atty. George Gascon said in announcing the charge. “It does not appear that Mr. Bucchere was attempting to stop.… He was trying to beat his own record in complete disregard for the safety of anyone else.”

Bucchere blogged that he had no recollection of the five minutes after the collision, “but when I came to, I was in a neck brace being loaded into an ambulance. I remember seeing a RIVER of blood on the asphalt, but it wasn’t mine.”

“The moral of this little story” is that everyone should remember to wear a helmet, he wrote in unprintable shorthand before Hui died. The original post, which has since been scrubbed from the Internet, was dedicated to “my late helmet. …May she die knowing that because she committed the ultimate sacrifice, her rider can live on and ride on.”

Bucchere’s attorney, Ted Cassman, said in a written statement that his client has cooperated fully with police and “believes that he entered the intersection lawfully and that he did everything possible to avoid the accident. His heart goes out to Mr. Hui’s wife and family.”

In the aftermath of the crash, the San Francisco Chronicle called on city officials to hold cyclists “accountable for rude, reckless and sometimes dangerous behavior.” Online commentators rued that “cyclists like this clown give all the rest of us a bad name.” City officials jump-started plans for a traffic school for first-time bike scofflaws.

But some questioned why Hui didn’t look before entering the crosswalk. Others observed that “cars and giant semi trucks run red lights all the time.” One called anti-bike commentators a “howling ignorant lynch mob.” The San Francisco Examiner editorialized that “rare pedestrian deaths” are “exploited by bicycle foes.”

Leah Shahum, the bicycle coalition’s executive director, called for “more enforcement of dangerous behavior among all road users.” Yes, she said, people misbehave on bicycles. But they also misbehave in cars.

“The fact that [Bucchere] was on a bicycle did not define him completely,” Shahum said. “There seems to be some tagging of, ‘Oh, you people who bicycle’ that doesn’t seem merited at all.”

Elizabeth Stampe, executive director of WalkSF, believes that the streets are not safe enough for pedestrians. But she argued that motor vehicles — not bicycles — are largely to blame.

Three pedestrians get hit by cars in San Francisco every day, said Stampe, who rents a car only for errands that can’t be done on foot or bike, like buying a case of soy milk. And 55% of all traffic fatalities here are pedestrians, she said, compared with 12% nationally.

“If everyone in a car right now were on a bike,” Stampe said, “the streets would be safer and cleaner.”

In fact, according to the most recent San Francisco Municipal Transportation Agency report, crashes in general have been going down over the last decade or so. The exception? Bicycle-related crashes have risen as the number of cyclists has grown.

A window on San Francisco’s space-sharing conflicts can be found along a beloved bike route called the Wiggle, which allows cyclists to avoid hills between the Panhandle and Market Street.

The intersection of Waller and Steiner streets is the Wiggle’s approximate midpoint. One recent Wednesday morning, 105 bicyclists zipped through the intersection in just 15 minutes. Ninety — including a man with a baby on board — ignored the four-way stop.

Watching the action from a cafe called Bean There, Rob Anderson called the city’s transit-first ethos “terrible public policy.” Incorporated into the city charter nearly 40 years ago, it states in part that “travel by public transit, by bicycle and on foot must be an attractive alternative to travel by private automobile.”

A comprehensive bicycle plan was passed in the 1990s, and an update was adopted unanimously by the supervisors in 2005. But a year later a lawsuit stopped it.

Anderson, a local blogger, brought the legal action, arguing that the plan required environmental review because it would take away traffic lanes and street parking, and reduce traffic flow. A judge agreed.

Eventually, the city “spent a couple million bucks … doing a big, doorstop environmental review,” Anderson said. “The EIR verified what we predicted was going to happen: You implement this project on the streets of San Francisco, and you’re going to make traffic worse for everybody except maybe cyclists.”

Although Anderson continues to fight the plan, the injunction was lifted nearly two years ago. Since then, 23 new miles of bike lanes have been carved out of city streets, and San Francisco’s first parking-protected bikeway was built in Golden Gate Park. The controversial thoroughfare has a pedestrian path, then a bike lane, then a loading zone, then a parking lane, then a driving lane.

It’s the kind of project everyone loves to hate, one that recently elicited online sneers: “Extend the bike lanes to go all the way out of town, one way only.” And: “I sat behind a long line of cars going nowhere into GG [Golden Gate] Park because of the new configuration… I also witnessed 2 bicyclists almost get creamed.”

Jason Henderson, a San Francisco State University professor specializing in transportation and land use, believes other cities can learn from this one’s growing pains. Sure, San Francisco is ahead of the biking curve in big-city California, but it hasn’t been easy.

“There’s a lot of good stuff going on here, " Henderson said, “but … it’s a guerrilla war, block by block, to get this kind of stuff done. And it’s extremely political.”

At the 18th annual Bike-to-Work-Day celebration — a two-wheel, City Hall love-fest not long after Hui’s death — helmeted elected officials acknowledged the difficulties but vowed to push on with bike-friendly improvements.

“We’ve come a long way,” said Board of Supervisors President David Chiu, “but we need to do better.”

maria.laganga@latimes.com