The Ultimate Guide to Choosing the Right Arrow Spine
How to match your arrow's stiffness to your bow's power for perfect flight and tuning.
Arrow spine refers to the stiffness of the arrow shaft—specifically, how much it flexes when shot. If your arrow is too stiff or too weak for your bow, it will never fly straight, making it impossible to achieve consistent accuracy. This guide explains how to read spine charts and select the perfect shaft for your setup.
Static vs. Dynamic Spine
Static spine is a standardized measurement of how much a 28-inch shaft flexes under a 1.94lb weight. Dynamic spine, however, is how the arrow actually behaves when fired from your bow. Factors like draw weight, point weight, and even your release type (fingers vs. mechanical) all affect the dynamic spine.
What Happens if Your Spine is Wrong?
An arrow that is 'too weak' (underspined) will flex too much, causing it to kick out to one side (usually the right for a right-handed archer). An arrow that is 'too stiff' (overspined) won't flex enough to clear the bow riser properly, often hitting the left. Both conditions lead to poor grouping and inconsistent broadhead flight.
Factors That Weaken Your Arrow
You can effectively 'weaken' an arrow (make it flex more) by increasing draw weight, using a longer shaft, or adding a heavier point. Conversely, you can 'stiffen' it by shortening the shaft or using a lighter point. Modern carbon arrows are rated in numbers like 300, 340, 400, and 500—where lower numbers indicate a stiffer spine.
FAQ
Should I err on the side of stiff or weak?
If you are between two spine sizes, it is almost always better to choose the stiffer option. Modern compound bows are much more forgiving of a slightly overspined arrow than an underspined one.
Does draw length affect spine?
Yes, a longer arrow of the same static spine will behave 'weaker' than a shorter one. Always consider your actual arrow length, not just your draw length.