San Francisco ? With its love of geek chic and congested streets, San Francisco might have been expected to embrace Segway, the environmentally friendly, self-balancing personal vehicle that promises to entice people out of their smog-spewing cars.

Instead, the city today becomes the first large municipality to outlaw the Segway Human Transporter on its sidewalks — more than a month before the chariot-like vehicles are made available to the public.

The Board of Supervisors acted last month following intense lobbying by Segway LLC in state capitols to change laws to permit the two-wheeled vehicles on sidewalks.

Thirty-three states, including California, approved Segway-enabling legislation. But that doesn’t mean major cities will roundly embrace the scooters touted by inventor Dean Kamen, when he introduced them to great fanfare in December 2001, as apt to “change civilization.” California’s law allows cities to opt out.

The upright device — controlled by body movements with the help of tiny computers and balance-controlling gyroscopes — has been tested across the country by postal workers, police officers and meter readers. They’re on sale to the public at Amazon.com for $4,950 each and will begin shipping in March.

Critics say the Segway is a safety hazard on sidewalks because it weighs 69 pounds and travels at up to 12.5 mph — three times faster than the typical pedestrian. No state is requiring that its drivers be trained, although some have set age and helmet requirements.

“We don’t want to say that it doesn’t ever make sense. But in urban settings there isn’t enough room for all the pedestrians,” said Ellen Vanderslice, president of America WALKs, a pedestrian advocacy group based in Portland, Ore.

In hilly San Francisco, officials feared the battery-powered Segways would cause more problems than they would solve, particularly for the disabled and senior citizens.

“There were statistics submitted to us about injuries, and the Segways themselves did not have adequate safety features to alert people they might be behind them,” said Tom Ammiano, a San Francisco supervisor who supported the ban.

Segway officials say the scooters have been tested for 100,000 hours on city streets across the nation without injury.

A Letter carrier delivers mail using the Segway Human Transporter on the streets of San Francisco. Late last year the San Francisco Board of Supervisors decided to ban the Segway from its sidewalks, a decision that will go into effect today.

Ammiano also said Segway’s campaign rubbed officials the wrong way.

“Segway didn’t help themselves by hiring very expensive lobbyists,” he said. “I think that backfired on them, too.”

New Hampshire-based Segway hired lobbying firms but has made no contributions to any public officials or candidates, said Matt Dailida, the company’s director of state government affairs.

Along with California, about half the states that passed laws to allow the Segway also permit cities to opt out, but so far most municipalities are taking a wait-and-see approach, he said.

Dailida says Segway has worked with many state and local legislators to show that the scooters are safe alternatives to cars. Buyers also must attend a multi-hour training course before the scooter is shipped to them, he added.

“We understand that this is an entirely new technology that each city needs to regulate,” he said. But “we think the action by San Francisco was premature.”

In California, Santa Cruz, Oakland and San Mateo are considering joining San Francisco in banning Segways from sidewalks. There is no similar move in congested Los Angeles, city officials said.