Compound Bows

A more recent innovation is the compound bow, which uses a system of cables and pulleys to make the bow easier to draw. Compound bows have achieved increasing popularity since a two-pulley design was introduced in the 1960s. They are used in field archery, in hunting, and in international target archery competition.

The limbs of a compound bow are usually much stiffer than those of a recurve bow or longbow. This limb stiffness makes the compound bow more energy-efficient than other bows, but the limbs are too stiff to be drawn comfortably with a string attached directly to them. The compound bow has its string attached 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. This causes the pulleys to pull the cables, which in turn causes the limbs to bend and thus store energy.

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.