Managing the mountain bike.

Soft rays reached through the dense, cathedral-high canopy and lit portions of the trail ahead with hemlock-filtered sunlight. I was hiking alone, about a mile from the trailhead, and just beginning to appreciate the solitude. Then a flash of light, and another - like the glare off a chrome bumper - poked at me through the trees. I rubbed my eyes ... but they were still there - wheels, gears, and polished chrome, well inside Michigan's Porcupine Mountains Wilderness State Park.

A man and woman were pedalling and, more often, pushing their sleek 10-speed bicycles up the trail. Something was not right, and I politely told them so. They responded that they were within the law. "Don't worry, though (gasp," one said, "we won't (wheeze) be trying this again."

That was 10 years ago, back when mountain bikes were but the pipe dream of a few California tinkerers. Now virtually every bicycle manufacturer offers a line of mountain bikes - those those knobby-tired, fat-framed, gearladen conveyances that scream for dirt roads and defy abuse. In many states, mountain bikes are outselling all other bicycles 10 to one. Though most of these never leave the city, an increasing proportion seem to find their way into the woods.

"We see bike tracks on all the trails now," says Porcupine Mountains manager Bob Vanderwall. In fact, mountain biked leave their waffle-like tracks on forest trails nationwide, providing an entirely new form of outdoor recreation - and some entirely new management concerns.

Mountain bikes have several important advantages over other forms of trail travel. They use no gas and produce no noise or fumes. They don't eat hay, grass, or anything else ... and they do not defecate. They are rugged, simple, and people-powered. Stress that last point - mountain biking can be a dandy workout.

Mountain biking is something like four-wheeling without a motor - or like hiking on wheels. "If the terrain isn't TOO forbidding," says one experienced biker, "a mountain bike is both easier and faster than hiking - even for a one- or two-night packtrip."

Mountain bikes are used for grueling organized races, leisurely family outings, and everything in between. They can add a new dimension to conventional outdoor pursuits like photography, camping, fishing, and hunting. Michigan's Upper Peninsula is laced with old logging roads that are favorite corridors for grouse and grouse hunters ... and ideal mountain-bike habitat. "I got on that bike and had one thought," said a friend after taking a test ride: "BIRDS!"

And there's no generation gap where mountain bikes are concerned. Though kamikaze, dust-busting races are best left to strapping teens, retirees have other uses for this vehicle. Witness the couple, inflated their rubber raft, and set out for a day's fishing. "They had to be over 60," said the observing ranger, "and they had it down to a science - this wasn't their first time."

Perhaps the mountain bike's greatest potential is as an alternative to motorized off-road vehicles, better known as ORVs. The hiker who takes up cycling gains an element of ease and speed, but hose who replace their motorcycles, ATVs (all-terrain vehicles), and ORVs with mountain bike help preserve the silence the every one appreciates. They also gain freedom from most mechanical failures, and expand riding opportunities, as mountain bikes are often allowed where motorized vehicles are not.

In fact, mountain bikers have free range of most public lands with only a few restrictions. Mountain bikes are prohibited from National Forest Wilderness Areas by the Wilderness Act of 1964 and a recent revision to the Code of Federal Regulations (36 CFR 261.16) that explicitly prohibits the "possession or use of a hang glider or bicycle." The National Park Service prohibits "wheeled vehicles" from its Wilderness Areas in Isle Royale and Yellow-stone. Other local regulations sometimes restrict certain trails to horse and/or foot travel only, but these are the exception rather than the rule.

Regulations aside, there are some places mountain bikes simply can't go. Steep, boulder-strewn mountain trails are still the domain of the horse and hiker. Deep sand is nearly impossible to negotiate on a bike, as are swamps, bogs, and wet meadows. And modern tire technology still bows to the mighty cactus. The wheel, great though it is, will never replace the hoof or the hiking boot.

Still, the benefits of the mountain bike are putting it in more and more forests, more and more often, and sometimes challenging the laissez-faire policy of management agencies. The bikes are especially profuse in California and the Rocky Mountain West. The only structured study of mountain biking on forest trails that I know of is the 1987 Kepner-Trego Analysis performed by the Santa Barbara Ranger District of the Los Padres National Forest in California. The Los Padres study was initiated in 1985 in response to complaints from hikers and horse riders about the use of mountain bikes on the trail system. The study involved eight months of public meetings and a two-month survey of 1,400 trail users. It addressed the three big concerns associated with mountain biking: social perceptions, safety hazards, and environmental impacts.

SOCIAL AND SAFETY

CONCERNS

The only constant is change ... and the fact that people will resist it. Some people feel that wheels just don't belong in the woods; others don't mind, as long as they aren't in THEIR woods. These feelings are a part of human nature, and are basic hurdles to the acceptance of bicycles on forest trails. "If the mountain bike had been around for 200 years, and the horse was just invented," says one trail ranger, "the horse would have the same trouble being accepted on the trail." In the Los Padres study, however, these perceptions were not a large enough concern to warrant restriction of bikers.

People are fairly adaptable, and most have no problem with the prudent use of bicycles on the trail. Ten years ago, I couldn't believe my eyes when I saw a bike on a forest trail - now I'm riding one.

The perceptual potholes are filling in, even in areas where mountain bikes have been especially controversial. In Boulder, Colorado, for instance, mountain-bike use became a heated issue with the Open Spaces Department and its already busy 100 or so miles of hiking trails over five years ago. "Since then," says Open Spaces assistant Kathy Vaughan-Grabowski," it seems to have quieted down to a happy compromise. People are realizing the benefits of each activity and thinking more rationally."

Part of the Boulder compromise was a prohibition of mountain bikes from about 90 percent of the city's trails, for safety reasons. Though there were no reported accidents involving mountain bikes, the trails were simply too crowded to allow for the mixing of bike, hikers, and horses.

The basic safety concern with bikes stems from their potential speed in relation to that of horses and hikers. Most bikers are responsible enough to control their speed and courteous enough to yield the right-of-way to pedestrians. It's the few hot-dogs who cause problems, like the one who irritated a Michigan hiker to the point of halting the bike with a walking stick to the spokes.

Safety was the primary concern in the Los Padres study, particularly because of a few rogue bikers with the habit of starting at the top of the trail and coasting down at kamikaze speeds. This obvious safety hazard was dealt with via a combination of education (a biking brochure) and trail design (rocks and other natural obstacles used as speed barriers in the trail). Yet of the 1,400 trail users surveyed, most had encountered mountain bikes on the trail and found bikers to be polite and not a safety hazard.

ENVIRONMENTAL IMPACTS

If mountain bikes can be accepted from social and safety standpoints, what about their impact on forest and trail? It's easy to see how bikes may have unique effects - they create a narrow, continuous track and can't step over rocks, mudholes, or vegetation. While some herbaceous vegetation and meadow grasses may be damaged by bicycle tires, these potential impacts are easily minimized by remaining on the trail.

In practice, it's hard to believe that mountain biking could produce any impact worse than hiking or horseback riding. Though bike tires are narrower than Vibram soles, the rider's weight is distributed over the contact area of both tires, and the bike generally weighs about 872 pounds less than a horse. Mountain bikes do not generate the dirt-digging torque of motorized ORVs, and bikers are not as likely as hikers to shortcut switchbacks.

These special impacts were considered by soil scientist Jim O'Hare during an inspection of some trails involved in the Los Padres study. His conclusion: differences in erosion rate attributed to hiking, equestrian, and biking activities are insignificant when compared to the inherent erosion caused by the existence of the trail itself. O'Hare is quick to point out that this rule may not apply to trails when they are wet, and he emphasizes that drainage is the single most important factor in proper trail design. Effective drainage will minimize mud and reduce erosion, while rocks and other natural obstacles in the trail will slow both runoff and speeding bikes. "If we build and maintain trails properly," O'Hare says, "we can manage them for mountain-bike use."

On Colorado's Arapaho and Roosevelt National Forests, recreation officer Rick Vallejos manages trails with mountain bikes in mind. "When we do trail work," he explains, "we don't mess around. We use 12- to 14-inch logs for water bars and steps, and leave them six inches above ground." While he rarely sees mountain bikes negotiate the logs, skid marks and scrapes across them attest to their stability under bike impacts - and the fact that not all bikers can "jump stumps" as some ads suggest.

Where trail work is concerned, mountain bikers can be a new source of volunteer labor for forest managers. In the Arapaho National Forest, a group known as Winter Park FATS (that is, FAt Tire Society) is engaged in a cooperative trail-management program with Pat Gill of the Sulphur Ranger District. In exchange for a free Forest Service special-use permit, FATS assumes responsibility for making and maintaining specified trails and roads. These are signed with the international bicycle symbol (not to exclude other users) in a way similar to snowmobile trail markings. FATS currently maintains about 150 miles of biking trails under this program, with a goal of 400 miles. Actually, the majority of this mileage is composed of abandoned logging and mining roads, which are often preferred by both managers and bikers.

Old roads make exceptional bike trail because they are wider, harder, less brushy, and have fewer obstacles - and hikers - than most hiking trails. Mountain bikes can travel farther and faster on roads than on trails, and can make the long loops that are required for a full day's ride.

Whether on roads or trails, the mountain bike can provide a new recreation adventure and add new dimensions to conventional outdoor pursuits. Hikers may get out more often and farther into the wood, campings gear can be carried on the bike rather than the back, and hunters and anglers can explore those way-back clearcuts and beaver ponds without an all-day walk or a noisy ATV. And forest managers can provide these new opportunities at little cost to the resource or agency.

Responsible mountain bikers can co-exist with other trail users under all but the busiest trail conditions while exerting minimal impact on the forest. Management of mountain biking on forest lands should focus on promoting a socially and environmentally responsible attitude, not just among bikers but among all trail users.

Buying a Mountain Bike

The modern mountain bike is a happy hybrid. It mates the fat, 26-inch tires of the heavy American bikes of the 1940s and '50s to the lightweight frames, grippy brakes, and plentiful gears of European-derived racers. Surprisingly, the result is a hardly go-anywhere machine at home in city or country. The mountain bike, in fact, is easily the most versatile bicycle ever created.

Today about 20 percent of all new bikes sold are of the knobby-tired, 18-geared, backcountry variety. High-ticket custom or semi-custom items just a few years ago, mountain bikes are nor offered by virtually all major makers and importers. Models, features, and prices have recently stabilized, and even lower-line models offer plenty of performance.

Muddying the waters, though, is an even newer hybrid, the so-called city bike, derived from mountain-bike parentage but designed for urban commuting.

Confusing? Absolutely So before buying, it's worthwhile to determine exactly what a mountain bike is. A true mountain bike - one that will be a delight to ride down twisting trails, along wooded firebreaks, and on sundappled logging roads - has a light-weight alloy frame designed for agility and speed. The complete bike, less any accessories, should weigh no more than 30 pounds.

Look for 18 speeds - three chainwheels in front times six cogs in the rear. For optimum gearing where the going gets tough, the smallest chainwhell should have no more than 28 gear teeth, while the largest coz in the rear should have at least 32. Tires should be 1.75 inches wide or wider. In mud, sand, or very rocky terrain, 1.9-inch, 2.0-inch, or a full 2.125-inch tire is better yet.

The Golden Mean of mountain-bike prices is currently between $350 and $400. In that range, mountain bikes will have good-quality frame tubes, light yet strong. They'll have sealed bearings, quality gear componentry and (almost always) the new click-in-dex shifting. Pay much below $350 and the bike may be missing some important features. Pay much more and you'll begin to enter a more competition-oriented category.

Mountain bikes in the $350-$400 range are offered by dozens of companies. Prominent brands include Nishiki, Diamond Back, Trek, Schwinn, Raleigh, Peugeot, Univega, Specialized, Panasonic, Motiv Montagna, Mongoose, Scott ... and many more.

As for where to buy discount stores are attractive, but the first-time buyer may do better in a specialty bike shop offering two to three models in the $350 to $400 category and then being guided by shop personnel. A large bike and accessory mail-order firm is Bike Nashbar.

DESIGNING TRAILS

FOR MOUNTAIN BIKES

The following tips were provided by soil scientists, foresters, and mountain bikers from some of the popular biking areas of California, Colorado, Wyoming, and Michigan. * Utilize abandoned or four-wheel-drive roads whenever possible. They have a harder surface, wider path, less brush, and fewer obstacles than most hiking trails ... not to mention fewer hikers. * Make sure trail drainage is sufficient to prevent extensive muddy sections and high erosion. * Use large, heavy logs for water bars and steps, and secure them in the trail solidly to withstand the bumping of bike tires. * Leave or place rocks, roots, and other natural obstacles in the trail to act as natural speed barriers and to discourage reckless bike racing. * Keep trails about 18 inches wide and maintain visibility with occasional brush cuttings. * Involve local bikers in trail designations, design, and maintenance whenever possible. * Discourage or prohibit bike use on trails that are already crowded with hikers and where environmental damage is imminent (bogs, sand dunes, etc.). * Explicitly denote areas where bikes are prohibited, and promote the suggested biking trails with signs and maps.

Richard T. Grost, a graduate student in wildlife at the University of Wyoming, thanks the Readers Digest Foundation and the University of Wyoming Department of Journalism and Telecommunications for funding portions of this project.