More than 10 million cycles–many of them thick-tired, soft-seated “mountain” bikes, good for both on- and off-road use–were sold last year. Bicycles, moreover, appear to be that rare kind of exercise equipment that actually gets used. Some 84 million cyclists are now pedaling around America on a regular basis. True, about 83.5 million of them should be over a few feet more to the right, but remember: this is the age of the megadistance cyclist. If a helmeted rider seems to weave a bit as the late-afternoon sun glints off his $500 Schwinn Voyager, that’s probably because he started the day in South Dakota.

Make that “he or she.” Market research indicates that there are as many women as men involved in the biking boom, and, for the first time in recent history, adult riders outnumber kids. “Everyone has a connection to cycling because everyone rode as a child,” says Nelson Pena, senior editor of Bicyeling magazine. “It’s a matter of rediscovery.” This time around, though, it’s not as simple as hopping on your Huffy. Today’s bikes, special clothing and high-tech locks can cost $2,000, and the reasons for riding get downright existential. “Americans have this compulsion to tame the land scape,” says Michael Marsden, professor of popular culture at Bowling Green State University. Adds Pena: “We are on our personal Tour de France.”

On the other hand, a lot of others are into cycling just so they can eat more. A biker, pedaling at 15 miles an hour, burns about 600 calories an hour–something that is not lost on the 7,500 people who plan to take part in the Des Moines Register’s Annual Great Bicycle Ride Across Iowa next week. The “Ragbrai” is a noncompetitive, seven-day, 495-mile meander that includes stops for food and fun. Next month bikers can attempt the “Hotter ‘N Hell Hundred,” starting in Waco, Texas. Then there’re the Pedal for Power from Maine to Florida, Sept. 22 to Oct. 13, and the scores of similar events held between now and November.

Century ride: Enthusiasts refer to a 100-mile (or 100-kilometer) trip as a “century,” but that accomplishment isn’t so impressive anymore. In Philadelphia a 65-year-old grandmother riding a three-speed bike and wearing high heels routinely completes the area’s annual MS 150, which raises money to fight multiple sclerosis. Arthur Scholbe, 69, of Cahokia, Ill., does double centuries on his $650 Cannondale. “I go out in the morning, I see deer, I see woodchucks, I see squirrels,” he says. Someday he may even see Freddie Hoffman, 31, of River Edge, N.J., who says he’s “practically married to my bike” and rides 50,000 miles a year.

Americans have been attempting century rides since the 1860s, when cyclists rode high-wheeled bikes on dirt roads. The renewed interest in biking is taking place now for several reasons. One is that Greg LeMond, the two-time winner of the Tour de France and latest Sports Illustrated “Sportsman of the Year,” has focused attention on cycling and made people feel it wasn’t nerdy to go around with what looks like Tupperware spaghetti collanders on their heads. The ranks of cyclists have also been swelled by former joggers who’ve discovered that bike riding is a lot easier on their backs and knees. People also like to bike because it’s an environmentally sound method of transportation.

But the key to long-distance cycling’s current popularity may be technological advances that allow cyclists to stay in the saddle. In the days of leather seats, says one equipment manufacturer, “you would wind up getting bunions on your butt.” Today one out of three new bicycle seats is filled with a polymer gel that molds itself to the rider’s form, and one company recently introduced a saddle pad that cyclists inflate with a handheld squeeze pump. Also on the market are gel-filled gloves, to relieve pressure on cyclists’ hands, in addition to the Lycra shorts equipped with gel-filled crotch sections, mentioned above. All this is known, in the sporting-goods business, as hitting the consumer where he lives.