A bicycle, or bike, is a simple machine, but it provides almost unlimited recreation and exercise, as well as fuel-efficient transportation. A bike consists basically of two wheels housed in a frame that includes a steering mechanism, a seat, and two pedals. In some countries, such as the People's Republic of China, bicycles are as important to transportation as automobiles are in the United States. Bike racing ranks behind only soccer as a popular sport in Europe and Latin America. Every year throughout the world, an increasing number of people buy bicycles. In the early 1980s about 9 million bikes were sold annually in the United States. China, however, is a much larger producer of bikes than the United States. History of the BicycleHistorians do not know who invented the bicycle. Leonardo da Vinci, the great Italian artist of the 15th century, drew some rough sketches of a contraption that looked like a bike. In 1690, a French inventor named De Sivrac built a hobbyhorse that had wheels but no pedals. It moved by means of the action of the rider's feet pushing against the ground. In 1816 Baron Karl von Drais, a German agricultural engineer, removed the head from the wheeled hobbyhorse and converted the front wheel into a steering mechanism. His machine had to be pushed by the rider's legs like a scooter. The development of the bicycle, or velocipede, as it was called in the 19th century, took its next major step about 1840. A Scottish blacksmith, Kirkpatrick Macmillan, built a simple machine with two pedals. They were connected by a rod and provided power to the rear wheel. Macmillan is sometimes credited with inventing the bicycle because the rider could travel without touching the ground and produce enough momentum to remain upright. Following Macmillan's invention, the bicycle became a popular and inexpensive means of transportation in England, France, and the United States. The roads were full of ruts and holes, but the development of a bicycle called the “ordinary” helped solve this problem. An ordinary had an enormous front wheel that measured as high as 5 feet (about 150 centimeters) or more, enabling the rider to cruise easily over rough terrain. However, the great height of the ordinary made it difficult to mount and ride, and an accident could cause serious injury. Bicycle riding became safer in 1886 with the appearance of the safety bike. This bike had today's familiar design—two wheels of equal size, with pedals driving the rear wheel by means of a chain and sprockets. Comfort remained a problem for cyclists because hard rubber tires made a rider's body feel every bump in the road. In 1888 John Dunlop of Scotland invented a pneumatic, or air-filled, tire that helped make bike riding much smoother. About 1900 an English manufacturer developed a 3-speed wheel hub for bicycles, which enabled riders to cover hilly terrain at higher speeds. Shortly before World War II, European bike racers began to use gearshift devices called dérailleurs, which gave them five speeds—and later ten—for climbing mountains. In the 1960s the 10-speed gearshift became common on bikes, though many still have a 3-speed system or no gearshift at all. Mechanical Principles of Bike RidingBicycling is basically a simple activity that people of all ages can enjoy. However, certain techniques of pedaling, braking, and shifting gears can improve both the pleasure and the efficiency of cycling. Pedaling. Regardless of the kind of bike being used, the way it is pedaled will affect the quality of the ride. The bike seat, sometimes called a saddle, should be high enough to permit the rider's leg to be almost fully extended while the heel is on the pedal. Toe clips are a great aid to efficient pedal action. These devices not only allow a strong downward stroke but also provide an upward thrust. The best way to achieve smooth, powerful pedaling is to practice using low to moderate gears. Most beginners pedal at a rate of only 50 to 60 revolutions per minute (rpm). At 70 to 90 rpm, riders approach peak efficiency and can pedal for hours without strain. Pedaling too long in high gears can cause fatigue and muscle cramps and can hurt the knees. Braking. One-speed bikes have coaster brakes, which operate by simply reversing the pedal stroke. 3-, 5-, and 10-speed bikes have handbrakes, which may cause the wheels to lock if the brake levers are squeezed too hard. A locked wheel could result in a skid or might even flip the rider over the handlebars. Handbrakes should be “feathered” by squeezing and then releasing the brake levers rhythmically. On a 10-speed bike, the front wheel supports most of the rider's weight and therefore has the best traction. The front brake, which can provide 2 1/2 times as much force as the rear brake, should be used first. Then the rider should apply both brakes until the rear wheel locks. He or she should immediately ease the pressure on the rear brake just enough to permit that wheel to roll, and then apply the brakes again. Shifting gears. Particularly on 10-speed bikes, gears are shifted in order to maintain a comfortable and efficient pedaling speed in response to terrain or weather conditions. A typical 10-speed bike has two sizes of chainwheel in front and five gears, or sprockets, in the rear. This combination provides ten speeds. The gears of most 10-speed bikes should be shifted only while the rider is pedaling. For flat, open-road riding, a middle gear is best, with the chain on the large chainwheel in front and the middle, or third, sprocket in the rear. For climbing hills, lower gears should be used by shifting the chain to a smaller chainwheel in front and a bigger gear, or sprocket, in the rear. For riding down hills or with stiff tailwinds, the bicycle should be put into a higher gear using the larger chainwheel and smaller sprocket. Kinds of BikesThe best-known types of bicycles are BMX bikes, utility bikes, and 10-speed bikes. The choice of a bike depends on the rider's needs. BMX bikes. Also called bicycle motocross or dirt bike, the BMX became popular in the early 1960s among teenagers who wanted to imitate motorcycle motocross competitors. Many BMX riders race on dirt tracks no longer than 3/4 of a mile (about 1.2 kilometers). They compete in bike handling, controlling skids, and leaping over various hurdles. Racers should always wear helmets, face masks, gloves, and protective pads. BMX bicycles can also be used for casual cycling. These bikes have no gearshift, and they vary widely in the quality of their frames and other parts. Utility bikes. These one- or 3-speed bicycles are heavy but reliable and are commonly used by messengers and newspaper carriers. Many have extra strength in front and can carry extra loads without becoming unstable. Utility bikes are usually ridden at slow speeds. 10-speed bicycles. United States manufacturers produce a larger variety of 10-speed bicycles than any other type of bike. The price of a 10-speed vehicle ranges from about 100 dollars to 3,000 dollars. It is determined by the quality of the components, the material used to make the frame, and the amount of handwork needed to construct the bike. A cyclist may have a 10-speed bike custom built to his or her specifications. The frame builder designs the bike according to the person's height, arm length, and inside leg measurement. The designer also chooses the parts that make up the vehicle and must consider the type of cycling for which it will be used. A custom-built bike can be constructed to provide the maximum speed for every ounce of energy used by the rider. Most bikes, however, are made to conventional standards in sizes indicated by the wheel diameter, which may range from 14 to 28 inches (about 35 to 71 centimeters). In addition to the 10-speeds, 12-speed bikes have become popular, and for the rigors of mountain touring, 15- to 18-gear systems are sometimes used. How Bikes Are MadeA quality 10-speed bike is generally constructed of lightweight high-carbon steel, although some frames produced in the 1980s were made of plastic. The steel frame provides strength, rigidity, lightness, and responsiveness. The best frames are “double butted”—that is, thick at the ends to give the bike stiffness and strength, and thinner in the middle for lightness. The first step in frame construction for a 10-speed bike is to polish and miter connecting metal tubes of the frame. The mitering process cuts an exact curve into the ends of the tubes so that they fit together precisely. The mitered tubes are joined by a reinforced device called a lug. Then they are fitted and held together by means of brazing. This operation requires extremely high temperatures, which can weaken the metal if not done expertly. The frame is cleaned with blasts of compressed air. Then the excess joining material around the lugs is filed away by hand, the corners are smoothed, and each joint is inspected. Finally, the frame is examined for any inadequate alignment. A quality bicycle frame typically receives five coats of paint—an undercoat, primer, base coat, top coat, and, finally, a lacquer. Then the front and rear forks, which support the wheels, are painted and fitted to the frame. Finally, if the frame is to be sold as a complete bike, it is clamped upside down and fitted with brakes, gears, handlebars, chainset, seat, pedals, and, lastly, wheels. Biking for RecreationTouring is one of the most satisfying activities in cycling. The best way to learn about touring is to join a bicycle club and receive the benefits of its members' knowledge and experience. The Bicycle Institute of America publishes a free directory of all bicycle clubs in the United States. Other organizations also serve cyclists. For example, American Youth Hostels provides members with handbooks, route information, and hostel listings. Another group, Bikecentennial, organizes bike tours throughout the United States and provides informational material, including a monthly newsletter. It also publishes The Cyclist's Yellow Pages, which lists national cycling associations, state agencies that furnish touring information, and general route data. The League of American Wheelmen is a national association that publishes a monthly magazine and provides touring information. Information about bicycling in other countries is available from most government tourist agencies. Bike Maintenance and Safety RulesFrom 10 to 15 percent of all bike accidents in the United States are caused by mechanical failure. Preventive maintenance is the best cure for this problem. The following are some standard recommendations for bike care. The first rule of maintenance is to keep a bike clean. Use a solvent—never water—to clean it, and avoid getting fluid on the brake pads and tires. Be sure that all parts are fastened tightly. Constant vibration or jarring can loosen nuts and bolts. Open handlebar ends can cause bad cuts, so loose plugs or grips should be replaced immediately. Handlebar tape not only is attractive but also absorbs sweat and road vibration. The tires must fit snugly and evenly on both sides. An ill-fitting tire could come off during a ride. The brakes must always be properly adjusted. When the handbrake levers are squeezed, they should come no closer than 1/2 inch (about 1.25 centimeters) to the handlebars. If they touch, the cable should be shortened. Also, the brake pads should be checked for wear. At least 1/8 of an inch (about 3 millimeters) of rubber should remain above the metal sides. The chain will move freely if treated with a spray lubricant. A 3-speed hub should get a teaspoon of oil. The steering head, cranks, pedals, and wheels should move freely but not excessively. Wheels need to be free of wobble. The rider can help by tightening loose spokes with a spoke wrench. The American Bike Month Committee recommends that bike riders should observe the following safety rules, especially on the open road: 1. Obey all traffic regulations, signs, signals, and markings. 2. Observe all local ordinances relating to bicycles, such as registration, licensing, and inspections, and rules about riding on sidewalks. 3. Keep to the right. Ride with the traffic, not against it, and stay as close to the curb as possible. Two or more cyclists should ride in single file. 4. Watch out for drain grates, soft shoulders, and other road surface hazards. 5. Watch out for car doors opening and for cars pulling into traffic. 6. Do not carry passengers and avoid transporting packages that interfere with your vision or control. 7. Wear a sturdy protective helmet. 8. Be extremely careful at intersections, especially when making a left turn. 9. Use hand signals to indicate turning or stopping. 10. Ride at night only if your bike has the required reflectors and lights. Bicycle RacingBicycle racing requires a bike with quality components and a lightweight frame. Riders should be in top physical condition and have exceptional bike-handling ability and judgment. There are many classes of bike racing for a variety of levels of ability and fitness. As with touring, membership in a cycling club is the best way to learn about bike racing. Most bicycle racing in the United States is done by amateurs. In Europe and many other areas where racing is popular, professionals dominate the sport. |