Compound bows are used most often for bowhunting and 3-D archery, but also for field and target archery. Their system of cams, strings and cables might make compounds look complicated, but they’re actually really simple to shoot. Here, Archer Merritt, 14, a four-time Virginia state champion 3-D archer, explains compound bow basics about the cams, cables, limbs and riser.
Buss cable (1): A separate cable from the bowstring, the buss cable is attached to the axle of the cams or the cam and idler wheel. The bowstring turns the cams, and the buss cable synchronizes the cams, or cam and idler wheel, so they turn at the same speed.
Cams (2): Cams or wheels are set at the end of the limbs on a dual-cam compound bow. When an archer draws the bowstring, the cams turn and allow archers to hold the bow at full draw longer than they could a recurve or longbow. Archer’s bow is a Mathews Solocam, which has one cam at the bottom and an idler wheel at the top.
Compound Bow: A compound bow uses cables and cams to store energy and reduce the holding weight at full draw. This reduction in holding weight at full draw is called “let-off,” and is especially useful for hunting because it allows hunters to hold a bow at full draw – and place an accurate shot – longer than if they were using another type of bow.
Dual cam: Dual-cam bows have a cam at the end of the top and bottom limbs.
Idler wheel (3): An idler wheel is set at the end of the top limb on single-cam compound bows. The bowstring runs along the idler wheel.
Let-off (4): Let-off is the amount of force needed to hold a bow at full draw (as Archer demonstrates in the photo above) compared to the amount of force needed to draw the bow. Once the bowstring is pulled far enough to rotate the bow’s cams, the weight drops dramatically as the archer completes the draw. A compound bow with 80 percent let-off allows an archer to shoot a 60-pound draw weight while holding only 12 pounds at full draw. The 60-pound draw weight is only felt during the initial draw.
Limbs (5): The top and bottom parts of the compound bow – the limbs – are stiff and do not bend like the limbs of longbows or recurves. The limbs on Archer’s bow are made of fiberglass.
Limb pockets (6): The butt-ends of both limbs on a compound bow fit into a notch – called a limb pocket – in the riser’s top and bottom. The limb pockets support the limbs and keep them aligned, which is essential for accurate shots.
Riser (7): The middle part of a compound bow, called the riser, includes the grip and holds accessories, including the sight and arrow rest.
String (8): The string on a compound bow runs between the cams, or the cam and the idler wheel, and holds a nocking point, and often a D-loop, peep sight and string silencers. When an archer nocks an arrow beneath the nocking point and draws the bowstring, the string turns the cams and transfers energy from the archer to launch the arrow toward the target.