Arrows Series – Part 3: Draw Weight

Obviously, force is required to move the arrow forward off the bow and it is generated from the tension of the limbs through the bowstring. Therefore, when purchasing arrows you need to know your draw weight so you can purchase the correct corresponding spine size for best performance. Limbs stiffness is determined by the amount of force, measured in pounds, required to draw the bow to a 28” draw length as outlined in the following Archery Trade Association (ATA) standard.

AMO BOW WEIGHT STANDARD

For Conventional Bows

Bow weight is the force required to draw the nocking point of the bow string a given distance from the pivot point of the bow grip (or the theoretical vertical projection of a tangency line to the pivot point parallel to the string). Draw length from pivot point shall be designated as DLPP and shall be referred to as TRUE

DRAW LENGTH.

For the purpose of uniform bow weight designation, bow weight is the force required to draw the bow string 26 1/4” from the pivot point. This weight will be marked on bow as being taken at 28” draw (26 1/4” plus 1 3/4” = 28”) See DRAW LENGTH STANDARD.

EXAMPLE: Weight Adjustment Range: 45/55 lbs. Weight Set At: 50 lbs.; Hold 32 lbs. Draw Length Range: 29” – 30”

EXPLANATION: The pivot point is a more realistic measuring point (when compared to the variations of profile of the back of bows at the handle section) for establishing bow weight since the pivot point is a constant in all bows as well as the contact point of the bow hand from which the true draw length is generated.

The 26 1/4” DLPP is the approximate equivalent of the 28” draw used previously on the more massive wooden handle bows.

Therefore, your draw weight is a combination of your draw length (See Arrow Series – Part 2 Measurements) and the combination of your riser (23” or 25”) and your limb stiffness (15#-50#).

For example, a 25” riser with a 34# long limb produces a 70” bow with a draw weight of 34 pounds at a 28” draw length.  If these same limbs were used on a 23” riser, the combination would produce a 68” bow with a draw weight of 36 pounds at a 28” draw length.

However, not everyone has 28” draw length, especially young archers whose draw length will change progressively with growth. So as a rule of thumb you can add or subtract approximately two pounds for each inch your draw length is over or under the 28” standard.

Using the previous example, if an archer has a 26” draw length and uses a 25” riser with 34# long limbs it will produce 30# of force at full draw OR uses the 23” riser with 34# long limbs it will produce 32#.

This is very important to select limbs that enable you to develop and compete however do not cause long-term physical damage. When purchasing limbs you need to determine if the limbs are too heavy, you can try this simple 7-second challenge.

7-second challenge

1. Draw the bow to the anchor
2. Hold seven seconds
3. Let down without lowering your hands, stay in set-up position to take a 2 sec brake,
4. Repeat several times.

If you cannot do it properly then the limbs are too heavy for you. If you find this challenge extremely easy, you can look at heavier poundage limbs, if you choose.

Now you understand draw weight and used in combination with your draw length you can see the arrows that match your equipment using a manufacturers arrow selection chart. In the up coming blogs we will try to examine the arrow spine, flex and stiffness.

Arrows Series – Part 2: Measurements

As we start to dive deeper about arrows, my goal is to simplify the information so young archers can have a good basic understanding; it is not meant to be all in compassing or a physics lesson, remember I am still learning too. Therefore, the next step is to understand how arrows are measured and how to determine draw length.

The Archery Trade Association (ATA) formerly the Archery Manufacturers and Merchants Organization (AMO) has the following standard for measuring draw length:

AMO DRAW LENGTH STANDARD

For Manufacturers

Draw length is a specified distance, or the distance at the archer’s full draw, from the nocking point on the string to the pivot point of the bow grip (or the theoretical vertical projection of a tangency line to the pivot point parallel to the string) plus 1 3/4”. Draw length from pivot point shall be designed at DLPP (Draw Length Pivot Point) and shall be called TRUE DRAW LENGTH.

EXAMPLE: 26 1/4” DLPP plus 1 3/4” is the equivalent of 28” draw.

For Dealers and General Use

For practical reasons not requiring precise terms, draw length is the distance, at the archer’s full draw, from the nocking point on the string to the back of the bow at the arrow rest.

EXPLANATION: The standard Manufacturers is consistent with the Bow Weight Standard as related to the pivot point. The DLPP plus 1 3/4” is compatible to previous concepts of draw length. Draw length for Dealers and General Use relieves the burden of preciseness not required for general use and facilitates determining arrow length. THIS STANDARD SUPERSEDES THE PREVIOUS STANDARD.

This can be technical and confusing, however with most recurve risers, the distance of the draw length pivot point (DLPP) to the front edge of the riser is 1 ¾”. Therefore, in general terms…

Your approximate draw length is equal to the distance from your string to the front edge of the riser at full draw.

You could use a measuring tape to measure this distance however unless you have a very consistent anchor point and good form you will have varying results, since you should measure several times. Therefore, any archer who is at the point they are fining tuning arrows for high-level of performance they should consult a professional. Otherwise, I would suggest you use the following simple method to determine your draw length.

Arms Length method

Using a ruler (or other straight stick), place one end in the “V” of your neck (where your neck meets your chest ) and relaxed, reach straight out until your palms touch the ruler. At the point for your fingers is your approximate draw length. Your arrows should always be at least 1” to 2” longer than your draw length for safety reasons and young archers often need to set their arrow length little longer ( 2” to 3” ) to allow for growth.

This gives you a basic understanding of draw length and how arrows are measured, however, things get very complicated for young competitive archers who are still developing and growing in size once you add-in arrow stiffness and flex, arrow cost, type of equipment and bow weight.

It is important to understand how things are measured so you can understand why you are using the arrows you have.  I highly recommend you visit your local archery professional for assistance.