Every bicyclist has to overcome wind resistance. Most recreational bicycles in which the rider sits up have very poor aerodynamics. While newer bicycles are being designed with better aerodynamics in mind, the human body is simply not well designed to slice through the air. Bicycle racers are aware of the problem of wind resistance and over the years have developed techniques for reducing it. Bicycle designers and inventors have experimented in developing alternative bicycle designs and HPVs (human- powered vehicles) with an emphasis on better aerodynamic performance.
Charley "Mile-a-Minute" Murphy was an early cycling racer. His "mile-a-minute" feat was accomplished in 1899. At that time he traveled faster than the fastest automobile. Notice the large windscreen on the train in front of him which greatly reduced wind resistance.
BICYCLE INSTITUTE OF AMERICA
Wind Resistance
Every cyclist who has ever pedaled into a stiff headwind knows about wind resistance. It's exhausting! In order to move forward, the cyclist must push through the mass of air in front of her. This takes energy. Aerodynmaic efficiency--a streamlined shape that cuts through the air more smoothly--enables a cyclist to travel much faster, with less effort. But the faster the cyclist goes, the more wind resistance he experiences, and the more energy he must exert to overcome it. When racing cyclists aim to reach high speeds, they focus not only on greater power, which has its human limitations, but also on greater aerodynamic efficiency.
Aerodynamic drag consists of two forces: air pressure drag and direct friction (also known as surface friction or skin friction). A blunt, irregular object disturbs the air flowing around it, forcing the air to separate from the object's surface. Low pressure regions from behind the object result in a pressure drag against the object. With high pressure in the front, and low pressure behind, the cyclist is literally being pulled backwards. Streamlined designs help the air close more smoothly around these bodies and reduce pressure drag. Direct friction occurs when wind comes into contact with the outer surface of the rider and the bicycle. Racing cyclists often wear "skinsuits" in order to reduce direct friction. Direction friction is less of a factor than air pressure drag.
On a flat road, aerodynamic drag is by far the greatest barrier to a cyclist's speed, accounting for 70 to 90 percent of the resistance felt when pedaling. The only greater obstacle is climbing up a hill: the effort needed to pedal a bike uphill against the force of gravity far outweighs the effect of wind resistance.