If you’re interested in learning about archery but don’t know where to start because the subject seems overwhelming, this piece is for you.
Arrow spine is essentially the measure of an arrow’s stiffness—how much it bends or flexes when force is applied. It is the backbone of your arrow’s performance. When you release the bowstring, the arrow flexes and then straightens as it flies toward the target. This flexing must be just right; too much or too little can send your shot off course. Selecting the correct arrow spine is crucial for accuracy, safety, and the overall efficiency of your shooting.
- Enhances Accuracy: Proper spine ensures the arrow recovers correctly during flight, maintaining a straight trajectory toward the target.
- Optimizes Energy Transfer: A suitable spine allows for efficient energy transfer from the bow to the arrow, maximizing speed and impact.
- Ensures Safety: Incorrect spine can cause excessive flexing, increasing the risk of arrow failure and potential injury.
- Improves Consistency: Matching spine to your setup leads to consistent arrow behavior, vital for skill development.
- Aligns with Bow Specifications: Different bows require specific spine ratings based on draw weight and length.
Arrow spine is calculated by measuring how much an arrow bends when a weight is suspended from its center:
- Support the arrow at two points,
- 28 inches apart, if the arrow measuring 29 inches long
- Suspend a weight of 1.94 lbs in the center of the arrow
- Measure how many inches the arrow bends, Deflection.
- Multiply the number of inches the arrow bends by 1000 to calculate the spine size
A stiffer spine will not bend as much as a lighter spine.
A smaller number = a stiffer spine (stronger arrow.)
A larger number = a flexible spine (weaker arrow.)
Here are some things to consider when choosing an arrow spine:
- Point weight: Adding weight to the front of the arrow weakens its spine, tips and inserts are measured in grains. It adds weight to the arrow and can effect how it flies.
- Arrow length: The length of the arrow is measured from the groove of the nock to the end of the shaft.
- Bow weight: The draw weight, how much force it takes to draw the bow, is a factor as well because stronger bows will deflect weaker arrows more and affect their trajectory or damage the arrow.
- It is common to shoot multiple types of spined arrow out of one bow as long as the spine does not stray too high or low from its optimal range.
- Ex. A 50lbs recurve bow optimally shoots 400 spine but if you are shooting further away and tend to shoot high you can shoot 500 spine so the arrow will drop more. The opposite is true if you shoot low at further distances.
- This only applies if you shoot consistently and shoot the same type of arrow (company and/or brand but with a different spine. An arrow can have a higher spine, but the lower spined arrow can still weigh more. That happens from arrow diameter OD and ID, arrow material, nock, tips, and insert choices.
- It is common to shoot multiple types of spined arrow out of one bow as long as the spine does not stray too high or low from its optimal range.
- Shooting Style: Traditional, recurve, or compound bows have different requirements.
- Compound bows are less likely to shoot multiple spines because their sights tend to have multiple pins for different distances making consistency all the more important.
- Traditional (Recurve or Longbows) tend use multiple spines more often because even if they do have a sight they typically have one “pin” (Olympic style) so for shooting at multiple distances you set the pin for your primary distance, 20 or 30 yards, and then learn how to adjust for 10, 40, 50, etc. That adjustment can be from changing the spine and hook and grip (hand placement on the string) or changing where they aim the pin at or near the target.
- Manufacturer’s recommendations: It is important to stick to the spine recommended for your bow. Each bow has specifications for each limb type. If you inherited a bow learn which company made it and even the model and look up the company and model and you will find it, it might take a while if its older though so be patient.
- Ex. Hoyt, Bear, KAP, Falcon, Sage McCormick, Striker, etc.
