Rather, they carry the corresponding draw weight, with which they should be shot. Wooden arrows are usually not marked with a spine measurement. Shooting technique (Mediterranean archers and thumb archers have different arrow dynamics).Arrow build (weight and shape of the arrowhead, weight, and shape of the fletching, possible tapering of wooden shafts).Arrow length (longer arrows are softer than shorter ones).The perfect stiffness of the arrows can depend on: They are a good starting point, but no silver bullet for every situation. Note: These values are static and relative. They relate only to the aforementioned conditions. Carbon fiber arrows measured with an ATA device will appear slightly “softer” than the manufacturer listed value. In other words, an ATA shaft will always be stiffer than an ASTM shaft with the same “number”. Arrow spines of carbon fiber and aluminum shafts are specified according to the “modern” ASTM standard.ĪTA and ASTM values can be converted as follows: ATA / 0.825 = ASTM, therefore ASTM*0.825 = ATAĮxample: A carbon fiber shaft has an arrow spine of 500 according to ASTM (28″ distance, 1.94 pounds). The weight is smaller, but the distance between the supports is greater, which should give a similar deflection. In this test, an arrow is attached to two supports, 28 inches apart, and pressed in the middle with a weight of 1.94 pounds (880 grams). F2031-05, they record the deflection in thousandths of an inch. The arrow spines of wooden arrows are measured according to the ATA system.ĪSTM is the American Society for Testing and Materials. A deflection in the arrow of 0.4 inches gives an arrow spine of 400. An arrow is attached to two supports, 26 inches apart, and pressed in the middle with a weight of 2 pounds (907 grams). When they measure the arrow spine, they record the deflection in thousandths of an inch. ATA, AMO, and ASTMĪTA (AMO) is the Archery Trade Association, formerly the Archery Manufacturers and Merchants Organisation.
ARROW SPINE CHART FOR FREE
Two examples for free apps are “B4 Shaft Selector” and “Arrows”. There are several mobile apps which provide precise information about different arrow types, including diameter, weight, and spine. Note: Arrow spine tables are only a recommendation and sometimes the number provided by the manufacturer does not really correspond to the measured values. Therefore, the following article provides a short overview of these measuring methods. The reason for this is that different standards measure the arrow spine in a different manner. Without knowledge of how arrow spine is measured, it’s just a number and not a very useful one at that. But what do these numbers for ATA and ASTM spine actually mean? They will also usually be specified when purchasing arrows. You’ll often find arrow spine measurements printed on the side of arrows by manufacturers. What Is Arrow Spine?Īrrow spine refers to the stiffness of an arrow. These differences in the application of force to the arrow also have an impact on the correct spine choice. Then the closer the bowstring comes to the bow, the faster it moves and the greater the resulting arrow speed.
ARROW SPINE CHART FULL
The cams allow for a low weight at full draw, and this corresponds to a small acceleration immediately after the release. The power is greatest at full draw, and the acceleration of the string diminishes as it moves closer to the bow. Recurve bows and longbows behave similarly during release. An incorrectly spined arrow doesn’t recover from the paradox as quickly and is much more likely to show up inconsistencies in an archers form. An arrow with the correct spine rating and length will recover perfectly from the archer’s paradox and give you a good arrow flight. The correct arrow spine can depend on the draw weight of the bow (at full draw), and also the bow type. The length of the arrow depends on your physical size, your flexibility, and your technique. Choosing the ideal arrow is a common problem for any archer.