The science of cycling

In a race that comes down to tenths of seconds and fractions of inches, riders often seek a competitive edge. But how much can science provide that edge?
There are two main factors that affect a rider’s performance.

Air resistance
Air resistance is the “major resistive force” for cyclists traveling at speeds of more than 10 miles per hour on a flat surface. Air moves above, around and under cyclists during the race, creating “pressure drag.”

Solution No. 1
Drafting. By drafting, cyclists take advantage of a “lower pressure vortex” — the area free from air resistance — created by the lead cyclist. Research shows that following a lead cyclist can create a 30 percent reduction in required power; riding in third further reduces this required power production by another 6 percent. Research concluded that alternating leads between four riders can increase performance by 25 percent.

Solution No. 2
Body positioning. To obtain optimum performance in a longer race (as compared to a sprint), a rider must balance comfort with aerodynamics. While every cyclist’s position is unique, proper technique centers around narrowing the body — the more width in the wind, the more resistance. Basic positioning includes placing the hands on the handlebars at the same distance as the shoulders,tucking the elbows close to the body and keeping the knees close to the bike.

Positioning is vital. In an upright position at 20 miles per hour, athletes would require nearly half a horsepower (345 Watts) just to overcome aerodynamic drag. At that position, the power to pedal would require 400 Watts — a level an average man could endure for about one minute. On the other hand, a “streamlined posture” on a racing bike reduces the energy required to 210 Watts to maintain a 20-mile-per-hour pace, which many athletes can sustain for an hour.

Cycling mechanics
Seeing the bicycle and human body working together as a single unit forces cyclists to consider the most efficient techniques and forms of cycling.
 
Pedaling cadence
In cycling, the pedaling upstroke can be as important as the downstroke. While the maximum power is produced on the downstroke, two factors affect the efficiency of the foot in the upstroke — gravity and resistance. The effort required to lift the foot off the pedal (to relieve resistance for the downstroke) is known as “pulling up.”

However, this resistance-relieving move requires so much energy to counteract gravitational pull that it is not seen as vital for efficient cycling. However, it is vital to begin pushing down as soon as possible after the pedals hit the 12 o’clock position. If a cyclist does not start pushing until the 30 or 40 degrees past that position, he is wasting that much potential power.
 
Sources: “Science and cycling: current knowledge and future directions for research.” Journal of Sports Sciences (2003). Science of Cycling edited by Edmund R. Burke (Human Kinetics Publishers, 1986). Bicycling Science by David Gordon Wilson, Jim Papadopoulos, F.R. Whitt