Supporters of the scooter say a ban would dent San Francisco's image as a hotbed of innovation that is friendly to new technology. It would also be a setback for Segway LLC, the maker of the scooters, which has touted them as an environmentally friendly alternative to motorized scooters and a potentially useful tool for government and corporations.

But opponents say the sidewalks of San Francisco are too crowded to allow the scooters to mingle with children, seniors and other pedestrians.

"These vehicles move up to 15 miles (24 kms) per hour and that's too fast to be on the sidewalks," said Gerardo Sandoval, a member of the board. "They are already too crowded with newsstands, sometimes with cars parked on them, with trees."

A spokesman for the mayor said Brown was unlikely to sign the legislation. "He's not supportive of regressive local laws that try to roll back the clock and try to prevent new technologies from reaching the market," said P.J. Johnston.

The scooters, once code-named "Ginger" but now called the Segway HT for Human Transporter, use an array of gyroscopes to mimic the body's five senses and ten microchips to function as a kind of brain. They are powered by advance servo-motors running on nickel and metal hydride electric batteries, and are ridden standing up.

WILD SPECULATION

The machine was invented by Dean Kamen - who also gave the world the portable insulin pump - and provoked wild media speculation about what "IT" could be after a leak on the now defunct media Web side Inside.com in early 2000.

Sandoval said the board was forced to act because California Gov. Gray Davis signed a law in September that allows the use of Segways unless local governments ban them.

Matt Dailida, who directs state government affairs at Segway, called the city's move premature.

"There are no Segways presently in use in San Francisco and over the last year, with tens of thousands of hours of use of Segways on sidewalks in major U.S. cities there has not been one injury to a pedestrian bystander," Dailida said.

A ban may come as a surprise to some whose image of San Francisco is of a free-wheeling city where most anything goes.

It also clashes with a popular, if out of date, perception created by the television series "The Streets of San Francisco" and the 1968 Steve McQueen movie "Bullitt" that residents of this hilly city are at ease with the idea of cars careening through the streets.

But a series of recent incidents in which pedestrians were killed by cars speeding through the city have heightened sensitivity to the intermingling of vehicles and people, Sandoval said.

"Two years ago we had more people killed by cars than we had murders in San Francisco," he said, adding that long-time residents of the city have complained to him about an increasing lack of civility by drivers that has paralleled a big jump in the number of cars on the road.

The ban has already passed a first reading in the council and is expected to pass its second reading next week. After that it would go to Mayor Brown who will have 30 days to veto it. Then the board has a month to override the veto. There are 11 city supervisors and Sandoval said the board would need an eight member majority to override.