The many parts of a compound bow are sometimes confusing for both beginner and amateur archers and bowhunters. Most experts also admit it took them some time to get fully familiarized with the many components, including the ever-mushrooming compound bow accessories.
In this article, we discuss the anatomy of a compound bow to show you a detailed list of the parts and the function each component plays in the whole compound bow shooting mechanism.
Let's shoot straight to the meat of the article.
Parts of a Compound Bow
Understanding how a compound bow works requires that you first understand the anatomy of the bow, with the ability to identify the different parts, their location, and the purpose of each. Here's a comprehensive list of the parts of a compound bow.
Photo credit: archerystreet.com
1. Limbs (Upper and Lower)
What This Is
The limbs are elongated and flexible pieces attached to the bottom and top of the riser at an angle of 45 to nearly 90 degrees. The limb attached to the top part of the riser is called the upper limb, while the one attached to the bottom is called the lower limb.
Photo credit: bowhunting.com
What It Does
Bow limbs flex each time you draw the bowstring to store the energy transferred to the arrow when you let go of the bowstring. As you pull the bowstring back, the tension created (the draw weight) is absorbed and stored in the limbs for transfer to the arrow.
Variations
Compound bow limbs are made of fiberglass, solid glass, or laminated composite materials that may comprise carbon, wood, and fiberglass.
Compound bow limbs come in various styles. Solid limbs are made of one piece of solid glass or fiberglass. One major disadvantage of solid limbs is that they are vulnerable to either breaking, cracking, or splintering.
Split limbs, which are more durable and comfortable to shoot than solid limbs, are two thin limbs fixed at the top and bottom ends of the riser. They are also more preferred because the hand shock they produce is lesser compared to solid limbs.
Split limbs have one major shortcoming - they usually wear out differently or warp, which tampers with arrow motion accuracy.
Most modern compound bows now use the parallel limbs style, an improvement of the split system in that the split limbs attach to the riser such that the upper and lower limbs run parallel to each other.
Instead of flexing back and forth, parallel limbs flex up and down to result in near-zero hand shock (bow jerking and vibration in the hand when you shoot) and low bow noise.
2. Limb Pockets and Bolts
What This Is
Limb pockets attach the limbs to the riser.
What It Does
The limb pockets hold the bow limbs in place to keep them from falling off the bow during use.
The limb bolts connect the limb pockets to the riser and can be loosened to reduce the draw weight or tightened to increase it.
Loosening or tightening the bolts is easy using a standard Allen key or a hex screwdriver.
Variations
Limb pockets can be made of ABS (Acrylonitrile Butadiene Styrene) plastic or machine aluminum. Machined limb pockets are more accurate, particularly over longer distances.
3. Cams
What This Is
Compound bow cams are the wheels or pulleys attached at the end of the bow limbs.
What It Does
Bow cams absorb the energy created by pulling the bowstring back. They store it and then transfer it to the limbs, creating let-off (mechanical relaxation of the bowstring to reduce draw weight held at full draw) during the process.
Cams - Elliptical wheels in blue (Photo credit: canadaarcheryonline.com)
Variations
Bow cams may be elliptical or circular, depending on the manufacturer. There are four cam systems used in compound bows today.
Single cam systems feature an idler wheel on the upper limb and a power cam on the lower limb. They are easy to maintain and use since no cam synchronization is required. They produce less noise than twin cams, but their arrow speeds are slower.
Twin cam systems have two symmetrically perfect wheels that are both either circular or elliptical. Maintaining a twin cam system is harder as it requires regular synchronization. However, they offer higher arrow speeds and are more accurate than single cams.
Binary cam systems have the two cams slaved to each other because of their interconnection with control cables. They are an improvement of twin cams and are less troublesome to maintain since they are self-correcting.
Hybrid cam systems feature two asymmetrical wheels with a power cam on the lower limb and a control cam on the upper limb. Most archers and bowhunters prefer them since they are easier to maintain and have even higher arrow speeds.
4. Sights (Bow Sight and Peep Sight)
What This Is
The bow sight is an adjustable aperture attached to the bow riser above the bow grip. The sight usually has a circular opening with horizontal or vertical colored aiming pins in the center.
The peep sight is a small hollow tube or circle placed above the D-loop between the bowstring strands by separating them, slipping the tube through the hole you have created, and tying it with a string that holds it in place.
What It Does
The bow sights are used to maintain the accuracy and consistency of shots. At full draw, you align your eye, the peep sight, the main bow sight aiming pins, and the target in one straight line.
Variations
Depending on the number of pins in the center, bow sights come as either one-pin bow sights, two-pin sights, three-pin sights, four-pin sights, five-pin sights, and seven-pin bow sights.
Fixed pin sights have multiple pins (of different colors) that lock in position and do not shift once you set them.
On the other hand, pendulum sights use only one pin placed on a pendulum within the sight bracket. They are a favorite of treestand bowhunters for better accuracy at extreme angles of depression.
Target sights, also called competition sights, are more complex and may include lasers as aiming tools. They offer high-precision shots in competitive archery with allowances for elevation and wind adjustments.
Peep sights have varying sizes and shapes. Usually, hunters prefer peep sights with a larger diameter for ease of sighting in low-light situations. On the other hand, archers prefer peep sights with a smaller diameter for more precision during aiming.
5. Arrow Rest
What This Is
The arrow rest is a platform on which the front end of the loaded rests before and during a shot. It attaches to the riser via the Berger hole.
What It Does
The arrow rest supports the arrow such that it doesn't shift and ruin shot accuracy.
Variations
Archers usually use a launch arrow rest in target archery. It looks like a prong and maintains minimal contact with the arrow.
Most beginners opt for containment arrow rests as they surround the arrow and hold it in position until the arrow is fired.
Bowhunters prefer the drop-away rest as it falls away and leaves the arrow's path clear upon release. Its major shortcoming is that it has moving parts that can easily malfunction.
The arrow's fletchings may also snug on the rest, ruining arrow speed and shot accuracy.
6. D-Loop
What This Is
Also called the string loop, the D-loop is a D-shaped device attached below and above the nocking point on the bowstring.
What It Does
The D-loop acts as a connection or hooking point for attaching the mechanical release aid, the accessory that fires the arrow when the trigger is engaged and assists in drawing back the bowstring to full draw. It also helps reduce wear and tear on the bowstring.
Variations
The D-loop can be made of thread, metal, or plastic-coated wire. Colors vary, depending on the manufacturer.
7. Grip
What This Is
The part where you hold the bow in your bow arm when carrying or shooting is called the grip.
What It Does
The grip offers the archer a place for holding the bow for stability during drawing and shooting.
Photo credit: archery360.com
It’s also the part you hold when raising the bow to the shooting position.
Variations
The grip can be made of metal, plastic, rubber, or wood.
For more variations, most manufacturers allow for customizations using aftermarket bow grips with different colors, hand positions, and sizes.
8. Bowstring
What This Is
The bowstring is the string where the arrow nocks and which the archer pulls back to full draw to arm the bow fully.
What It Does
When you pull back the bowstring to full draw, it causes the limbs to flex and store energy to transfer to the arrow when you fire away. Upon release from the full draw, the bowstring launches the arrow toward a predetermined target.
Variations
Traditionally, bowstrings were made of flax, animal sinew, gut, silk, twisted rawhide, or hemp.
Modern bowstrings are made using synthetic fibers or materials such as Dacron (highly durable) and Vectran and Kevlar (less stretch and higher arrow speeds, but Kevlar is less durable.)
HMPE (High-Modulus Polyethylene), a mix of Dyneema and Spectra, is also used on modern compound bows because it lasts longer and has higher arrow speeds than Dacron, Vectran, and Kelvar.
Some compound bow strings are made of steel.
9. Stabilizer
What This Is
A compound bow stabilizer is a rod attached to the riser below the grip. It sticks out in front of the bow.
What It Does
The stabilizer counter-balances the bow’s weight for stability during aiming, full draw, and during and after the shot. Some also help reduce vibration and noise production upon shooting.
The stabilizer also helps balance the bow and resist or reduce torque, rotation, or twisting in the bow riser when you fire the arrow.
Variations
Not all compound bows come with pre-installed stabilizers. However, each bow has a universal-fit mounting hole for the stabilizer. Stabilizers come in different shapes, colors, and sizes.
Bowhunters use stabilizers 4-12 inches long for easy movement in the woods, while target archers can use stabilizers between 24 and 48 inches long for greater stability.
While earlier stabilizers were made of metal, modern ones are made of lighter materials such as rubber, ABS plastic, and carbon.
10. Cables
What This Is
The cables are cords that run from one cam to the other between the limbs but do not contact the arrow at all.
Photo credit: archery360.com
What It Does
The cables ensure the cams rotate properly during the draw. They also compress both limbs to increase the energy to be transferred to the arrow.
Variations
While earlier compound bow cables were made using plastic-coated steel, modern ones are made of high-modulus polyethylene (HMPE.)
11. Cable Guard
What This Is
Also called the roller guard, the cable guard is a short pole that connects perpendicularly from the bow riser to the bowstring.
Photo credit: bowhunting.com
What It Does
The cable slide attaches to and slides along the cable guard. The guard also pulls the bow cables to one side to keep them off the arrow's path and the shooter's arm.
Variations
The cable guard is usually made of fiberglass, plastic, carbon, or machined aluminum.
12. Cable Slide
What This Is
The cable slide in a compound bow is a small movable slide that attaches to the cable guard.
What It Does
The cable slide works in tandem with the cable guard to keep the cables off the arrow's path. It helps hold the cables to allow for sliding along the cable guard each time the shooter draws or releases the bow.
Variations
Compound bow cable slides are made of plastic or high-quality aluminum alloy.
13. Speed Nocks
What This Is
Speed nocks are small weights added in strategic positions on the bowstring.
Photo credit: bowhunting.com
What It Does
Speed nocks give the bowstring more power for faster arrows speeds. They help reduce bowstring oscillations as the cams pull the string during the shot. The string thus returns to the cam groove more quickly.
The arrow speed increases since the speed nocks reduce friction and the energy lost during the unwanted string oscillations.
Variations
Bowstring speed nocks are made of brass, but some manufacturers add some wrapping material for aesthetics, personalized looks, or to indicate the manufacturer's logo.
14. String Silencer
What This Is
A string silencer is an attachment put around the bowstring or between its strands, usually close to the speed nocks.
What It Does
The silencer helps reduce the vibrations and noise the bowstring produces when released to launch the arrow. It comes in handy, especially for bowhunters, to help eliminate the chances of spooking animals with a high sense of hearing, such as whitetail deer.
Variations
The string silencer is made of rubber as a standalone piece near the speed nocks, or a cluster of short rubber strands fixed on the bowstring near the cams.
15. Axles
What This Is
Bows cams rotate on 'shafts' or 'hinges' that act as the load-bearing points for each cam.
What It Does
The axles provide rotating points for each cam to help them move and bear the tension exerted on them during the draw. They determine the axle-to-axle length, commonly called the ATA length, which is measured between the cams with the bow undrawn.
The ATA distance is a significant consideration when buying a compound bow. A bow with a higher ATA distance is more forgiving and has a smoother draw process, while one with a shorter ATA length is easier to use and produces higher arrow speeds.
Target archers prefer compound bows with 38-42 inches ATA span for more stability at full draw.
Although some modern compound bows have ATA lengths as low as 18 inches, most treestand bowhunters prefer 30-33 inches, while those hunting from ground blinds prefer ATA lengths between 27 and 30 inches.
16. Draw Stop/Backstop
Photo credit: outdoorempire.com
What This Is
In a compound bow, the draw stop or backstop is a small projection on each cam that prevents pulling the bowstring back beyond the full draw position.
What It Does
Adding the draw stop for preventing going beyond the full draw helps protect the bow, especially the cam systems, the limbs, the bowstring from cracking or breaking due to overstretching or over-flexing. The aim also remains steady, and the shots are consistent.
17. Kisser Point/Kisser Button
What This Is
The kisser point is a small anchoring device placed on a bowstring slightly above the D-loop. It lies near the corner of the archer's mouth when the bow reaches full draw.
What It Does
The kisser button or point forms part of the anchor point on your face to help produce consistent and accurate shots. However, most archers consider it optional and do not add to their bow.
Photo credit: archerytalk.com
18. Riser
What This Is
The riser is the middle section of the bow between the limbs and is the foundation of the complex modern bows.
What It Does
The riser features many universal-fit and placement holes or cut-outs for adding other bow components and accessories such as sights, wrist slings, arrow rests, stabilizers, quivers, among others.
Variations
Traditional risers were either machined or forged from aluminum. Some modern risers are made of lightweight carbon fiber.
Additional Compound Bow Parts
The 18 parts above are the main components of a compound bow. However, other optional parts are crucial for shooting accuracy, consistency, and comfort. Here are some such parts.
Bow Sling
Most people prefer to add a bow sling or wrist sling to their compound bow. The sling helps hold the bow firmly in the hands before, during, and after the shot. It ensures stability for consistent and accurate shots.
After the shot, the bow sling counters the force that jerks the bow forward, thus ensuring it doesn’t fall off your bow arm or ruin the shot with a lousy follow-through.
Quiver
A bow-mounted quiver provides quicker access to arrows than other hip or back quiver placement positions. It's an addition to the bow that enhances your comfort and speed shooting prospects when hunting or at competitive target archery.
Release
A compound bow release is a mechanical device attached to the D-loop to help draw the bowstring and launch the arrow toward the target once the trigger on it is engaged.
Conclusion
While they may appear too complex and intimidating to use, learning the different parts of a compound bow sets you up for success in archery and bowhunting. Some parts to pay close attention to include the cams, bowstring, grip, silencer, stabilizer, and sights.
Once you know the parts, you can easily tell how they work in the entire system to shoot arrows, making it easier for you to learn how to shoot and maintain your bow.
