Handlebars Are Only One Part Of The Mountain Bike Experience

Mountain Bike Handlebars are rugged, fat-tired machines, like bikes before the 10-speed revolution, yet built with strong, lightweight alloy frames and multispeed gear changers found on European-style racers. Not all of these other users of the public lands are happy to see the arrival of this new and ambiguous breed, half outdoorsman and half motorcyclist-without-the-motor.

Environmentalists say the Mountain Bike Handlebars has climbing ability, with their rugged, knobby tires, make it hard for riders to resist leaving established trails to cut new tracks through delicate landscapes.

Like city pedestrians who voice fears of being hit by a bicycle as they are crossing a street, walkers and equestrians complain about the silent, speedy vehicles appearing suddenly from around corners.

''I can see that what they're doing is fun, but it's fun at my expense on Mountain Bike Handlebars,'' said Mary Holden, a Denver jogger who complained of being ''ambushed'' by mountain bikes when she runs along the banks of the Platte River.

Last year, as a result of complaints, Boulder, Colo., closed its Greenbelt Park to mountain bikes. The city relented by opening a few trails only after an outcry from riders. One of the keenest arguments now under way is how to regulate mountain bikes in national wilderness areas, regions designated by Congress as roadless, where ''vehicles'' are specifically outlawed.

Last year the United States Forest Service began ticketing mountain bikers in Colorado's Snowmass-Maroon Bells wilderness areas, arguing that the bikes were vehicles under the law. Mr. Odell's group is appealing the ruling to the Forest Service. Meanwhile, the fat-tired bike has earned other fierce adherents.

''It's whole new, relaxed approach to biking,'' said Mark Wynn, of Tucson, Ariz., who was interviewed in the Arizona desert on his way to Denver. ''It's a little slower than a skinny- tired bike,'' said Mr. Wynn, who is formerly of Asbury Park, N.J., ''but you don't have to worry about everything on the road because you can run over it.''

The development of the mountain bike has also rekindled a sense of patriotism among some people who dislike the domination of American bicycles by the finicky, skinny Continental 10- speeds.

''I'll never forget the day the first 10- speed showed up on the block when I was a kid,'' said Richard Sterns, a Denver freelance artist who grew up outside Chicago. ''Right away I knew - all the kids knew! - that our old, fat, wonderful Schwinns were finished, out to lunch forever. We had to get 10 speeds. And I resented it, but I had to go along.''

Mountain Biking