Compound Bow

A compound bow is a modern bow that uses a levering system, usually of cables and pulleys, to bend the limbs.

The limbs of a compound bow are much stiffer than those of a recurve bow or longbow. This limb stiffness makes the compound bow more energy-efficient than other bows, in conjunction with the pulley/cams. The compound bow has its string applied to pulleys (cams), and one or both of the pulleys have one or more cables attached to the opposite limb. When the string is drawn back, the string causes the pulleys to turn. When the draw commences, the archer has reduced mechanical advantage, but during the draw, as the pulley cams rotate, and the archer gains mechanical advantage over the bending limbs, more energy is stored, in comparison to other bows.

The use of this levering system gives the compound bow a characteristic draw-force curve which rises to a peak weight and then "lets off" to a lower holding weight.

The compound bow is little-affected by changes in temperature and humidity and it gives superior accuracy, velocity, and distance in comparison to other bows. The compound bow was first developed in 1966 by Holless Wilbur Allen in Missouri, and a US patent was granted in 1969. The compound bow has become increasingly popular. In the United States, the compound is the dominant form of bow.

In literature of the early 20th century, before the invention of compound bows, composite bows have been described as "compound". This usage is now outdated.