Compound Bows 101

The compound bow is the preferred weapon of choice for serious archers. The traditional recurve bow still retains a loyal following -- and is used exclusively for Olympic competition -- but the compound bow features user-friendly engineering and a lighter weight. Many non-Olympic events are available to the competitive compound-bow user.

  1. Compound Bow History

    • Exasperated by the ease at which whitetails were evading his arrows, Holless Wilbur Allen designed a bow that enhanced arrow velocity. Alternating the material from which the bow was made -- and tweaking the shape of the bow's limbs -- did little to improve the speed and success of his arrows. Applying the laws of physics to his problem, Allen conceived the idea of a pulley bow with shorter limbs than the recurve. After experimenting with pivot-hole placement, he finally achieved a result that provided increased speed and enhanced arrow penetration. Allen filed for a patent in 1966, receiving it three years later.

    Compound Bow Anatomy

    • An eccentric wheel rotates at the upper and lower ends of the compound bow. The wheels are called eccentric because they rotate away from the bow structure. The upper wheel is known as the "idler," and the lower is called the "cam." Both are often referred to as cams. Attached to the idler is the curved upper limb. The lower limb, also curved, attaches to the cam. Both limbs are bolted to the vertically oriented bow riser. Mounted to the riser are the sight window, the arrow shelf, the grip and the stabilizer. The latter serves to keep weight balanced. The draw string is attached to the cams at different perforations, depending on the desired draw weight and draw length. Cables are also connected to the cams to keep them in synch.

    Compound Bow Fitting

    • Prior to taking a compound bow afield, an archer is advised to set the draw-weight and draw length to levels that allow for personal comfort, appropriate power and speed of arrow delivery. For hunting, a minimum draw-weight of 45 lbs. is needed; the norm hovers between 50 and 70 lbs. Effective draw-length brings the string approximately even with the user's lips. Since individual arm lengths differ, this is not a hard and fast rule. One inch of draw-length translates to 10 fps in arrow travel-speed. The advantage of the compound bow is the concept of let-off. When the archer reaches full draw-length, the bow decreases the resistance below that of the full draw-weight. The percentage of that reduction is the measure of let-off.

    Compound Bow Applications

    • Compound bows are effective for new hunters, experienced archers, and young people. The let-off feature benefits those whose upper body strength is still developing, or those whose muscles take time to adapt to the motion of drawing a bow.