BICYCLES OF CHILDHOOD PEDAL INTO SUNSET.

Byline: Peter T. Kilborn The New York Times

These are exquisite days to ride a bike in the all-American, middle-American boyhood home community of Mark Twain. Children can ride to school, to the Tom Sawyer Cave a couple miles south of town, to the banks of the Mississippi for fishing or to a park to play pitch and catch.

They can and they used to, but they don't any more. Hannibal's parks, river banks and schools are almost barren of bikes. Plastic riding toys cover the lawn of Ya Gotta Have It, a store that sells secondhand toys, but the few bikes are stored in the back room. A late-afternoon tour of a subdivision yielded two people on bikes and four on riding lawn mowers.

As vacation approached for the 350 pupils, only four bikes were parked outside Oakwood Elementary School. Kenneth Treaster, principal of the 950-student Hannibal Middle School, said, ``I can remember one kid riding a bike here in the three years I've been in this building.''

As Hannibal goes, so goes the nation. In the shadow of a long, slow decline in cycling generally, the bicycle as a century-old symbol of childhood freedom and transportation is nearly extinct.

``Biking as a form for children to get from one location to another has become very, very rare,'' said Richard Killingsworth, a health scientist for the Centers for Disease Control and Prevention in Atlanta.

Since the 1970s, bike-riding to and from school has declined by 60 percent to 70 percent among children 7 to 15. Fewer than 1 percent ride bikes to school, including only 2.5 percent of those who live within two miles of school, Killingsworth said.

For children, bicycles have been muscled aside by parental fears of crime and traffic, tight scheduling of organized play, television and computer games. This century's longest stretch of prosperity has conspired against bicycles, too. With higher household incomes and an abundance of part-time jobs for teen-agers, increasing numbers of 16-year-olds have cars.

``I was talking about it over the weekend,'' said Cathy Carver, 42, who was having coffee at the Mark Twain Dinette. At a garage sale, ``they had a black 10-speed for $2,'' she said.

``Thing of the past,'' commented Greg Henderson, 43, a grain inspector sitting at the counter beside Carver. ``Nintendo,'' he said. ``They'd rather do that than go out and ride a bike.''

Carver has a daughter, 11. ``She's never had any desire to have a bike,'' she said.

Henderson said his daughter did. ``She had two bikes. But by the time she got to 12, she was done.'' She just stopped riding bicycles, he said.

It is not that bicycles are disappearing. The industry reports robust sales of mountain bikes, but mostly to adult riders, as well as soft-saddled comfort bikes for aging baby boomers and recumbent bikes that let riders lie back to pedal.

But over all, Huffy Corp., in Dayton, Ohio - largest bike maker in the United States - reports that industry sales of bikes have fallen from the levels of the 1970s and stayed flat at 15 million to 17 million for a decade. Since the population has increased since the '70s, the per capita decline is sharp.

And fewer people use the bikes they have. Elliot Gluskin, research director for Bicycling Magazine, said the number of riders dropped to 43.5 million from 56.3 million just from 1995 to 1998.

``We are living in a much less friendly bicycle environment,'' said Tom Doyle, vice president for research at the National Sporting Goods Association.

Ben Silverman, owner of Agoura Cycling, also said things have changed in the world of bicycles.

``In this area kids are more into mountain bike riding, . . . not so much riding their bikes to school,'' he said. He said lightweight motorcycles and motocross racing also are popular.

Bicycles were a mode of transportation 20 years ago, and now they have become more a form of recreation, said David Burns, manager of Reseda Bicycles.

``The children of today have far more to occupy their time - video games, computer games, roller hockey, soccer,'' Burns said. ``The ratio of Game Boys to kids' bicycles is probably 3-to-1.''

There are few statistics on children who ride bikes, but no one denies that the number has declined.

Not so long ago, Diane Colbert, 38, seemed glued to a bike. ``I had a 10-speed,'' she said about years when she was growing up in Bowling Green, Mo., south of Hannibal. ``I rode 15 to 20 miles a day. I was everywhere on my bike. You didn't have to worry who was out when.''

But these days, safety is a big issue. Colbert and her husband, Jerry, 40, were holding a garage sale at their house in a subdivision without sidewalks at Hannibal. Their son, Jaron, 12, was trying to sell his bike, which he has outgrown, for $15.

He would like another bike but can live without one. ``I'd like to ride to the place where I play baseball,'' he said, ``but there's the traffic.'' So his mother drives him the two miles.

Daily News Staff Writer Eric Leach contributed to this story.