Compound Bow Fitment Guide
This is personal: Draw lenght
What is a draw length? Compound bows are a little different from traditional recurves and longbows. Unlike traditional bows which can be drawn back practically any distance, compound bows are engineered to draw back only so far – and then stop. This distance is known as the bow’s “draw length” – and it’s controlled by the mechanical systems on the bow. The trick is … the mechanical setting of the bow and the physical size of the shooter need to match. If your physical size requires a bow with a draw length setting of, say, 29 inches, then it can be said that “your draw length” is 29 inches. So both YOU and the BOW have a draw length to match up. Determining draw length fitment begins with measuring the person (more on that in a moment) and then finding a bow which can adjust to fit that person – not the other way around.
What is full draw? It’s important to note that compound bows are designed to be shot only from the full-draw position – that is, with the bow drawn all the way back (until it stops). If a compound bow is set for a 29″ draw length, for example, it should always be drawn back to a full 29″ and then shot from that position. You should never attempt to shoot from the middle of the powerstroke. You only shoot after you reach full draw. If you haven’t shot a compound bow before, don’t worry. It’s much easier to “feel” than explain. It’s almost like opening a car door. You just know when the door is all the way open and when to stop pushing, right? Same with a bow. You’ll know when you’re at full draw; it’s quite obvious. You draw the bow back until you feel the mechanical stop – then you take aim – then you shoot! Easy.
Overdrawing the bow? On most compound bows, the mechanical stop at full draw is quite firm. Once you hit the stop, it’s exceedingly difficult to pull the bow back any more (and you shouldn’t try). A bow that’s set for 29″ draw cannot be drawn back to 30″ or 31″ without modifying the mechanical setup on the bow. Never attempt to forcibly overdraw a bow beyond the mechanical stop. Draw your bow in a slow and controlled manner. Just after your bow achieves full let-off, you will feel the touchdown at “the wall.” That’s it. You’re ready to shoot. Most modern compounds take less than 20 lb. of pressure to hold back at full draw. So if you’re still grunting and straining at full draw, you’re trying to forcibly overdraw the bow (which can damage you and the bow). So just be cool. When you get to full draw, relax. You made it.
What is a “proper” draw length? Ask ten different archery experts for advice about your draw length, and you’re likely to get ten different answers. There are a number of methods and devices commonly used to determine a “proper” draw length – few of which agree. The truth is … your “proper” draw length is the draw length at which you are the most comfortable and the most accurate. No matter what a chart or device (or expert) says, if you shoot best at a given draw length … THAT’S your perfect draw length. Some shooters experiment a little and “tweak” their draw lengths up or down as their technique evolves, but most adults just find a comfortable draw length and stick with it. If you’re new to the sport, don’t worry. We’ll help you estimate a good starting point.
Armspan method works! Here’s a reliable measurement method we have utilized for fifteen years … the trusty Armspan/2.5 method. To measure your draw length, 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. If you are a person of average proportions, your arm-span will be roughly equal to your height (in inches). So there is often a direct correlation between a person’s height and their draw length, so you may use the scale below if you wish. But if you are particularly lankly, stocky, etc., the arm-span/2.5 method will probably yield the most reliable estimate.
Speed freaks beware! Most shooters tend to set their bows for too much draw length – particularly men. This could be a side-effect of male machismo (we all think we’re a little taller than we actually are), but sometimes it’s a conscious decision to gain more speed and power. The longer your draw length, the longer your bow’s powerstroke will be – and the faster your bow will shoot. As a general rule, 1″ of draw length is worth about 10 fps of arrow velocity. Bows are IBO Speed rated at 30″ draw length. So if your particular bow has an IBO speed of 340 fps, and you intend to shoot the bow at 27″ draw length – you should expect an approximate 30 fps speed loss right off the top (310 fps max). This is one of the reasons that so many archers – particularly shorter guys – choose inappropriately long draw lengths. We strongly discourage this practice, as the added speed is a poor trade-off for the loss of comfort and control. A fast arrow is no good if you can’t reliably put it on target. Get that barbed-wire tattoo if you must, but don’t make the macho mistake of shooting more draw length than you need.
Does a string loop add draw length? It seems to be common knowledge among archery enthusiasts that a string loop equals an extra 1/2″ of draw length. To be honest, it would be easier to just agree and move on, but that’s not technically correct. Forgive us for popping the industry bubble here, but here’s the deal … the AMO/ATA specs for measuring draw length reference the actual bowstring at its nocking point – not necessarily the point of attachment from which it is drawn. If you draw a compound bow back to full draw, the official draw length is found by measuring the distance from the nocking point on the string, in a line perpendicular to the center line of the bow, to an imaginary point above the pivot point of the grip, plus 1.75 inches. Did you get that? If not, you can bone up on more compound bow techno-bits by reading our Compound Bow Selection Guide later. But the fact is, a string loop – or lack of a string loop – has nothing to do with the (official) mechanical draw length of a compound bow … but …
Does a string loop change the “feel” of my draw length? Ah-ha! That’s the better question. The answer is maybe. At full draw, your anchor point should be comprised of several key reference points (physical connections between you and the bow), whatever you prefer those connections to be. Common reference points are nose to string, arrow nock to corner of mouth, kisser button touching lip, hand against the cheek, knuckle in the ear, etc. A string loop will have NO effect on how the string touches your nose, or how the nock of the arrow touches the corner of your lip, but a string loop will position your release hand about 1/2″ farther back on your cheek. If that makes you “feel” like you have a longer draw length, then yes. Otherwise, no.
A final thought on draw lengths: If you’re new to the sport, don’t get too carried away dissecting yourself down to the micron. You’ll have better luck if you just play the averages and choose an initial draw length that’s similar to others of your same size and stature. Fortunately, on most bows, making a minor draw length change is pretty simple. So it’s not quite a life or death decision to start. However, as you become more immersed in the sport and begin to “fine-tune” your game, you may wish to experiment a little with your draw length.
A Heavy decision: Draw weight
What is draw weight? The draw weight of a compound bow is the amount of pulling force required to draw the string back – simple enough. But keep in mind, the draw weight of a compound bow is neither static or 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 controlled 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 us some ergonomic advantages that traditional equipment cannot. As a general rule though, less effort is required at the beginning and at the end of the compound bow drawstroke, and somewhere in the middle you’ll hit the dreaded “peak weight” – the hump – the point where your maximum effort is required. This is where a compound bow’s draw weight is measured – at the heaviest point of the cycle. When selecting a draw weight, this is the mark you should be concerned about.
Comfort is the key: There are several factors to consider here, beyond just brute strength. First and foremost, we strongly recommend that you choose a draw weight that is COMFORTABLE for you and suitable for your particular purpose. In recreational archery pursuits, a bow with too much draw weight will simply make you less successful and make the sport less enjoyable to you. A good rule-of-thumb is to choose a draw weight that requires about 75% of your “maximum” strength. If your bow is too heavy to draw back (overbowed), and you can only shoot a few times before you’re fatigued, then you’ll be reluctant to practice and improve your game. With that said, you also want your bow to shoot with as much gusto as possible, particularly if you’re big game hunting, so you shouldn’t choose too little weight either (underbowed). Again, the right balance between comfort and performance will probably be at your “75%” mark.
Hail the macho man! We bowhunters tend to be tough-guys – and some of us just can’t resist choosing heavyweight bows (+75 lb. peak). Unfortunately, a heavyweight bow choice usually turns out to be a mistake. Just because you finished your P90X DVD set and your goatee has filled in, that doesn’t necessarily mean you possess the back and upper-body strength to comfortably manage an 80# hard cam bow. Few guys do. Unless you’ve been shooting hundreds upon hundreds of arrows per week, and you have been specifically conditioning yourself to use a heavyweight bow, we suggest you leave the heavyweights alone. Shooting a powerhouse draw weight sounds glamorous, but it will likely just ruin your experience. If you’ve never used a compound bow before and have no idea where to start, here are some general guidelines. You should apply your common sense here and interpret this chart with due respect to your own age and general physical condition.
65-75#: Large Frame Men (180+ lbs.)
55-65#: Med. Frame Men (150-180 lbs.)
45-55#: Large Frame Women (160+ lbs.)
45-55#: Small Frame Men (120-150 lbs.)
40-50#: Athletic Older Boys (130-150 lbs.)
30-40#: Med. Frame Women (130-160 lbs.)
25-35#: Small Frame Women (100-130 lbs.)
25-35#: Larger Child (100-130 lbs.)
15-25#: Small Child (70-100 lbs.)
What about speed? Contrary to popular belief, more draw weight doesn’t automatically yield a significant increase in hunting arrow speeds – particularly for draw weights above 60 lb. peak. Since industry standards require at least 5 grains of arrow mass per pound of draw weight, a 60# peak bow only requires a 300 grain (5 x 60) arrow. A 70# peak bow requires a 350 grain (5 x 70) arrow, and an 80# peak bow requires a 400 grain (5 x 80) arrow. So although the heavier bow will generate more KE (penetration) at the target, the increased arrow mass requirements tend to offset the potential speed gains of shooting more draw weight. So if you decide to pull 20% more draw weight, you probably won’t get 20% more arrow velocity. A responsible pro-shop never sets up a bow to shoot underweight arrows. The 5 grain per pound rule must always be followed for safety reasons.
Dangerous game! With all that said, there may be some specific applications where heavyweight bows really are called for (African Elephant, Black Rhino, Cape Buffalo, Nile Crocodile, etc.). Of course, if you’re going to hunt THOSE animals with a bow, you really should be a Macho Man. If you’re going on a special dangerous game hunt, then by all means, bring whatever firepower your outfitter requires. But for North American big game animals, a heavyweight bow is completely unnecessary, though we should probably note, some states require a compound bow to meet certain draw weight minimums (usually around 40#) in order to hunt large game like Whitetail Deer. Check with your state’s governing agencies, and always observe the rules and regulations for legally harvesting game in your state.
Pump it up! If you still don’t feel good about your level of bowhunter brawn and buffness, don’t worry. The “archery muscles” used to draw a bow are primarily large muscle groups in your upper back (the same muscles you use to row a boat or pull-start a lawn mower). Most people don’t specifically work to exercise these muscles. So you will probably find that once you do put them to work, your “archery muscles” will gain strength quickly and drawing your bow will become easier over time. Fortunately, most bows come with at least 10 lbs. of draw weight adjustment. So if you are a new shooter, you may wish to begin with your bow set at a lower draw weight – and gradually “crank-up” the draw weight as you become more conditioned.