Understanding The Impact Of Bow Length On Performance

The length of a compound bow is important for achieving the right draw length, which is the length you draw your bow to before firing. The right draw length is essential for accurate shooting.

Compound bows are different from traditional bows in that they have a specific maximum draw length that must be set for the shooter. The draw length of a compound bow is controlled by the mechanical systems on the bow and is usually adjustable within a range of a few inches.

To find the correct draw length, you can use the fingertip method, which involves measuring the tip of one middle finger to the other and dividing that measurement by 2.5. This will give you the approximate draw length that you can use to find the right size compound bow for your needs.

The brace height, or the distance from the string at rest to the pivot point of the bow's grip, is also an important consideration when choosing a compound bow. A shorter brace height will result in an increased power stroke but may be less forgiving to shooter errors. On the other hand, a taller brace height provides more stability and is often considered more forgiving.

The axle-to-axle length, or the distance between the centres of the steel axles at the end of each limb, is another specification to consider when choosing a compound bow. Longer bows with longer axle-to-axle lengths tend to be more stable and easier to hold steady while aiming.

Ultimately, the right compound bow length depends on your personal preferences, physical condition, and the type of shooting situations you plan to encounter.

Draw length: the distance a bow can be drawn back, controlled by its mechanical systems

Unlike traditional bows, which can be drawn back to practically any distance, compound bows are designed to be drawn back only so far. This distance is known as the bow's "draw length", and it's controlled by the mechanical systems on the bow. The trick is to match the mechanical setting of the bow to the physical size of the shooter. If your physical size requires a bow with a draw length setting of, say, 29 inches, then your draw length is 29 inches.

Determining draw length fitment starts with measuring the person. A good way to find a reasonable starting point is to use the Armspan/2.5 method. To measure your draw length requirement, determine the length of your arm span in inches. Stand with your arms out and palms facing forward. Don't stretch when measuring. Just stand naturally. Have someone else help you and measure from the tip of one middle finger to the other. Then simply divide that number by 2.5. The quotient is your approximate draw length in inches for your body size.

The draw length of the bow is adjusted on the bow's cam(s) – either by changing the cams entirely or by making an adjustment to a small metallic insert in the cam called a module. Rather than machine entirely different cams for each draw length, manufacturers make different bolt-on inserts for that one small area of the cam (the module). So, rather than change a whole cam to adjust a draw length, you just change a little module in the cam. Many manufacturers even go a step further by making sliding modules instead of separate inserts, allowing for draw length adjustments without the need for additional parts.

It's absolutely critical that the bow you select has enough mechanical adjustment to fit your body. Bow companies try to engineer bows to fit their intended target audiences. For example, a typical draw length range to accommodate most adult men is about 25 to 30 inches. So, not surprisingly, many men's bows are engineered to adjust within that range, give or take.

It's important to note that every compound bow has a limited range of mechanical adjustment, usually just a few inches. Therefore, if a particular bow cannot adjust to fit your body's draw length requirement, that's a deal-breaker. Choose a different bow.

Draw weight: the force required to draw the string back

The draw weight of a compound bow is the amount of force required to pull the string back. The draw weight is determined by the combination of the bow's limbs and the bowstring. As the bowstring is pulled back, it stores energy in the limbs, which is then transferred to the arrow when it is released. The higher the draw weight, the more energy is stored in the bow, and the faster the arrow will travel.

The draw weight of a compound bow is neither static nor linear. That is to say, it isn't like pulling on a rope with dead weight at the end, and the draw weight doesn't get progressively harder the farther you draw the bow back (like a longbow). The draw weight of a compound bow is managed by the geometry of the cam system, so the required effort rises and then falls during the draw cycle. That's sort of what makes a compound bow "compound."

The draw cycle is mechanically manipulated to maximize energy storage and give ergonomic advantages that traditional equipment cannot. As a general rule, less effort is required at the beginning and end of the compound bow drawstroke, and somewhere in the middle of the powerstroke is the "peak weight" - the point where maximum effort is required. This is where a compound bow's draw weight is measured.

The draw weight of a compound bow is the amount of pulling force required to draw the string back – simple enough. But it's worth noting that a compound bow's draw weight is neither static nor linear. That is to say, the force needed to draw the string doesn't increase in a straight line as you pull it back. Instead, it rises and falls during the draw cycle due to the geometry of the cam system.

The draw weight of a compound bow will depend on the thickness, length, shape, and preload of the limbs, as well as the design of the cams and the limb pockets. When buying a bow, you'll typically choose between a few limb options, which offer a range of draw weights. For example, you might choose between 40-50 pounds, 50-60 pounds, or 60-70 pounds. Within each range, you can adjust the draw weight to any value (e.g., 51 pounds, 54 pounds, 58 pounds, etc.). However, you cannot adjust the draw weight outside of the specified range. If you decide you want a different draw weight range later on, you'll need to install new limbs.

The draw weight of a compound bow plays a crucial role in its performance. It affects the speed and power of the arrow, as well as the accuracy of the shot. A higher draw weight will result in faster arrows, but it will also require more strength to draw the bowstring back, which can lead to fatigue and reduced accuracy. On the other hand, too low of a draw weight may not provide enough power to the arrow, impacting accuracy and distance. Therefore, choosing the right draw weight is essential for optimal performance.

When choosing a bow, it's important to select a draw weight that matches your needs and abilities. As a general guideline, start with a draw weight that is no more than 50-60% of your maximum strength. This will allow you to practice and build your strength gradually while still enjoying the sport. For beginners, it's recommended to start with a lower draw weight, typically 20-30 pounds for a recurve bow and 20-30 pounds for a compound bow. As you gain experience and strength, you can gradually increase the draw weight. For experienced archers, a draw weight of 40-50 pounds is often a good starting point, and you can adjust it depending on your specific needs, such as hunting or target shooting. It's important to note that women and children typically have lower strength levels and may need to start with a lower draw weight.

Bow length: longer bows are more stable, shorter bows are better for tight spaces

Bow Length: Longer Bows vs. Shorter Bows

The length of a compound bow, also known as the axle-to-axle length, is an important specification to consider when purchasing a bow. This length is the distance between the axles at the end of each limb, which attach the rotating eccentrics (cam or idler wheel) to the bow.

Longer bows, generally those with an axle-to-axle length of 34 inches or more, tend to be more stable and easier to hold steady while aiming. This increased stability makes them more accurate over longer distances. They are also preferred by finger shooters, as the string angle at full draw is less acute, providing more space for the fingers at the nocking point.

On the other hand, shorter bows, typically those with an axle-to-axle length of 29 inches or less, are more manoeuvrable and better suited for tight spaces, such as hunting from a treestand or saddle. They are also lighter in weight, making them a good choice for hunters who need to travel long distances.

However, it is important to note that the difference in stability and accuracy between longer and shorter bows is not drastic. Modern compound bows tend to have axle-to-axle lengths ranging from 30 to 33 inches, with very few falling outside this range. Therefore, the decision to choose a longer or shorter bow depends on the specific needs and preferences of the archer, such as the type of hunting they will be doing and their desired level of stability and manoeuvrability.

Brace height: the distance from the string at rest to the pivot point of the grip

Brace height is the distance from the bowstring at rest to the deepest point of the grip, also known as the pivot point or the throat. This measurement is important as it affects the performance of the bow. The brace height is usually between five and ten inches, with most modern compound bows having a brace height of around six to seven inches.

A longer brace height gives a more forgiving geometry to the bow riser, making it easier to repeat your shot. It also gives more room for your arm and clothing, reducing the chance of hitting the string when shooting. However, a longer brace height results in a slower arrow speed as the arrow spends less time on the string.

Conversely, a shorter brace height provides a faster arrow speed as the arrow spends more time on the string. However, this can make the bow less forgiving as any imperfections in form or technique will be magnified. A shorter brace height also increases the likelihood of bowstring slap, which can be painful and alter arrow flight.

The ideal brace height depends on the type of bow and the user's skill level. For example, hunters typically require faster arrow speeds and therefore prefer a shorter brace height. On the other hand, target shooters or beginners may prefer a longer brace height for improved accuracy and forgiveness. Ultimately, finding the right brace height is a matter of experimentation and determining what works best for the individual archer.

Axle-to-axle length: the distance between the axles at the end of each limb

Axle-to-axle length is an important specification to consider when choosing a compound bow. This refers to the distance between the axles at the end of each limb of the bow. While a longer bow will provide more stability, a shorter bow will be less stable. The difference in stability is not as significant as that between a rifle and a handgun, but it is still noticeable.

The axle-to-axle length of a compound bow typically falls within the range of 28 to 45 inches. For hunting bows, the sweet spot is considered to be between 30 and 33 inches, with very few bows falling outside of this range. A longer axle-to-axle length, such as 38+ inches, may be preferred by finger shooters as it provides a less acute string angle at full draw. However, most modern compound bows are designed with mechanical release in mind rather than finger shooting.

When choosing a compound bow, it is important to consider your intended purpose and personal preferences. If you plan to use the bow in tight quarters, such as in a treestand, a shorter axle-to-axle length may be more suitable. On the other hand, if you anticipate facing open field targeting situations, a longer bow length would be more advantageous. Additionally, longer bows tend to be easier to hold steady while aiming, making them a better choice for beginners.

It is worth noting that the classification of a bow as "short" or "long" is somewhat subjective and depends on the context. For bowhunters, a bow with an axle-to-axle length of 34 inches or more would be considered a specialty product, while for pure competition shooters, this length may be more common. Ultimately, the right compound bow for you will depend on your individual needs and preferences.

Frequently asked questions