Compound Bow Fitting Guide
Compound Bow Fitting Guide
What you need to know when you place your order for your new bow.

Compound Bow Fitting Guide

The purchase of a compound archery bow can be a complicated task.  While you can go to a sporting goods store and pick something up off the rack buying compound bow that works well for you takes not only a good quality archery bow but a thoughtful selection process.  There are five major decisions you have to make when choosing and setting up your compound archery bow:

1.  Do you need a right or left handed bow?  

While this seems obvious, it really isn’t.  Generally, people who are right handed use right handed bows and the same for left handed people.  However, reality is if you are right handed you will be holding your right handed bow with your left hand so be sure, if you are shopping on your own, to pick the one that you hold in the opposite hand of your dominant hand.  

In addition to that confusion, there is a small part of the population that has backward eye dominance.  What this means is that while they are right handed, they are left eye dominant.  Eye dominance is which eye you naturally favor during tasks that require hand eye accuracy.  It is easy to test one’s eye dominance.  Make a triangle with your hands at arm’s length and then focus on an object in the room.  Close each eye, one at a time.  The eye that you can see the object with is the dominant eye.  If your eye dominance is backwards, then shooting any archery bow can be awkward.  Most experts recommend retraining your body to the dominant eye rather than trying to adjust your shooting style or retrain yourself to use your other eye as the dominant one. 

2. What weight range should I choose for my compound archery bow’s limbs? 

Your compound archery bow comes with limbs that, unlike archery recurve bows and archery long bows, can be replaced and adjusted.  These limbs are available in ten pound weight ranges, such as 40 to 50 pounds.  When choosing limbs, the draw weight can be adjusted within that range but cannot be adjusted out of the range.  If you have a 50 to 60 pound limbs on your bow, the draw can be set between those numbers but if you decided you need a 65 you will have to purchase new limbs.  The upside is that you only have to purchase new limbs, rather than having to buy a new bow as would be the case with archery recurve bows and archery long bows. 

Bows are more efficient when operating close or at the top rating for the limbs so this must be factored in when deciding which limbs to get and have setup.  If you decide, for instance, that you want 60 pounds of draw and that you are completely set on that, picking 50 to 60 pound limbs for your archery compound bows is going to be the better choice.  The 60 to 70 pound limbs are more popular but work at their most efficient from about 67 pounds to 70 pounds. 

For youth archery bows, the small gain in efficiency should be ignored due to cost concerns.  Kids grow fast and build strength quickly when they begin shooting and will easily move through the range of a limb.  If you pick a 30 to 40 pound limbs for your youth archery bows, your child will zoom through that range in a matter of weeks anyway so the loss of efficiency becomes a very short term problem anyway.  

3. What draw weight should I pick?

Hand in hand with the limbs is the overall discussion of what the optimal draw weight should be.  The honest answer is that it varies quite a bit and that there are legal matters to consider as well.  
The first concern for draw weight is to make sure that it is sufficient to be legal for whatever game you are hunting for in the state you are hunting in.  Most states, at the very least, regulate the draw weight required to hunt larger game such as Whitetail deer.  The reality is that while these laws are on the books they reflect what should be considered good common sense. 

There are some states that disallow the use of archery recurve bows or archer long bows for certain game species because they cannot reliably get enough kinetic energy for good penetration.  Archery compound bows excel in getting consistent and larger amounts of kinetic energy from any given amount of draw weight. 

Even if there are not laws on the books, there are excellent guidelines for archery compound bow’s draw weights based on what is being hunted.  In general 40 to 50 pounds is sufficient for taking down a deer, 50 to 60 pounds can take down larger species such as elk.  For those wanting to hunt wild boar, bears or other animals with thick skins or thick pelts, 70 pounds or more of draw weight is recommended. 

Ultimately the draw weight is based on what you are comfortable with.  The average male of average strength can handle 55 to 65 pounds of draw weight comfortable and an average female of average strength can handle between 30 and 40 pounds of draw weight.  For youth archery bows, draw weights range from 10 pounds for very small children to up to 50 pounds for athletic older kids. 

The muscles used to draw archery bows are large muscles in the back and will build up strength quickly.  Having a bow that requires too much draw force can be uncomfortable and can affect not only your enjoyment of archery, but can affect your accuracy as well.  Finding a happy medium and then working up to an optimal draw weight is the best approach when buying and setting up your archery compound bows. 

4. Determining draw length

Archery compound bows differ greatly from archery long bows and archery recurve bows in that there is a set draw length that every draw must work from.  With a traditional bow, you can vary the amount of kinetic energy by varying the draw.  With a compound archery bow, you must shoot from the full draw position every time.  However, you cannot go past this final position because there is a stop built in.  Determining the optimal draw length is easy and this is an important part of getting your archery compound bow setup properly.  The formula for determining optimal draw length is your arm span from finger tip to finger tip, divided by 2.5.  You will need a friend to help you measure your arm span and want to make sure that you measure without stretching your arms out farther than they naturally go.  If you have a big chest, it is best to measure from the back to make sure the measurement is accurate. 

Many beginners set their compound archery bow’s draw length for too much draw length.  This yields painful string slaps to the forearm, poor shooting form and worst of all inaccurate arrows.  When in doubt, going a little shorter than the formula can yield a better time and a more accurate shot with your new archery compound bow. 

5.  What is a let-off percentage and how does it affect me?

One of the biggest benefits of archery compound bows is how adjustable they are.  In archery recurve bows and archery long bows, as you pull the string back, it requires more and more force.  In contrast, compound archery bows require less draw weight at the end of the pull than in the middle of the pull and most compound bow manufacturers allow you or your chosen setup person to adjust whether the percentage of let off is high or low.  A higher percentage means that you will have to hold less draw weight at full draw; while a lower percentage means that you are holding more of that weight. 

There is more explanation needed before making a decision though.  While the obvious choice seems to be the higher let-off percentage, it does affect the speed at which the arrow transitions from rest to movement when you release the bow string.  Resistance is also vital in keeping a good stance and being accurate.  That said, most modern compound archery bows are set with a high let-off percentage. 

There are two other reasons for a low let-off percentage, aside from the slight performance advantage.  The first is that some states regulate the let-off percentage allowable for certain game species, especially larger game species.    The second is that the Pope and Young club, the club that catalogues record kills, allows only a 65% let-off percentage to be considered for their record books.  If you were to bag a record with a high let-off compound bow, they would publish the kill but place an asterisk beside the record indicating it was a high let-off that did it.