Worked examples of spine selection for three common setups — see the process once and you can do it forever.
Worked examples of spine selection for three common setups — see the process once and you can do it forever. Follow the steps in order — each one builds on the last.
Step 1: Gather your three numbers
Peak draw weight, finished arrow length, and point weight. Everything else is refinement.
Step 2: Run the baseline
Use our Arrow Spine Calculator or the manufacturer chart with your three numbers. Example: 60 lbs / 28.5″ / 100 gr → 340 spine.
Step 3: Adjust for length
Cutting from 30″ to 28″ stiffens dynamic spine about one group — our 45 lb / 30″ / 125 gr recurve example lands on 500 instead of 600.
Step 4: Adjust for point weight
Going from 100 to 150 grains weakens spine about one step: a 70 lb / 29″ / 150 gr heavy-FOC build moves from 300 to 250.
Step 5: Bareshaft verify
Charts get you to the right shelf; a bareshaft group next to fletched arrows at 20 yards confirms the buy.
Why Arrow Spine Is So Important
Spine is the stiffness of your arrow shaft, and it is the most misunderstood number in archery. When the string releases, the arrow flexes around the riser in a motion called archer’s paradox, and the right spine flexes just enough to clear cleanly and recover into straight flight. Too weak and the arrow over-flexes and fishtails, too stiff and it cannot recover, and either way your accuracy and broadhead flight suffer no matter how well you tune everything else.
Spine matters even more for hunters shooting broadheads. The blades up front amplify any flexing error, so an arrow that groups fine with field points can plane wildly with a broadhead if the spine is wrong. Choosing correctly from the start saves you from chasing a tune you can never reach with the wrong shaft.
What You Will Need
- Your draw length and your finished arrow length
- Your bow’s draw weight and a manufacturer spine chart
- Your intended point weight, including insert and broadhead or field point
- A few bare shafts and a target for bare-shaft verification
Common Mistakes to Avoid
- Reading spine off draw weight alone and ignoring arrow length and point weight
- Forgetting that a longer arrow acts weaker and a shorter one acts stiffer
- Overlooking heavy broadhead and insert weight, which weakens dynamic spine
- Trusting field-point grouping and skipping a broadhead or bare-shaft check
- Buying shafts before confirming the chart against your exact configuration
Pro Tips for Choosing Spine
- Start from the manufacturer chart using draw weight, arrow length, and point weight together
- Remember a longer shaft flexes weaker, so trimming length stiffens the arrow
- Heavier points up front make the arrow act weaker, so account for your broadhead weight
- Bare-shaft tune to confirm: a bare shaft that hits with your fletched arrows means good spine
- When between two spines, the slightly stiffer choice is usually more forgiving with broadheads
Final Word
Spine is the foundation under every tune you will ever build. Get it right using all three numbers, draw weight, arrow length, and point weight, then confirm with a bare shaft, and your arrows recover cleanly and your broadheads fly true. Get it wrong and no amount of rest adjustment will save you, so choose carefully before you buy a single shaft.
Frequently Asked Questions
What is arrow spine?
Spine is the stiffness of the arrow shaft, which determines how it flexes around the bow at release and recovers into straight flight.
What affects which spine I need?
Three things together: your draw weight, your finished arrow length, and your point weight including insert and broadhead.
Does arrow length change spine?
Yes, a longer arrow behaves weaker and a shorter one behaves stiffer, so trimming length effectively stiffens the shaft.
How does point weight affect spine?
Heavier points up front make the arrow act weaker dynamically, so a heavy broadhead may require a stiffer shaft.
How do I confirm I chose the right spine?
Bare-shaft tune by shooting an unfletched shaft alongside fletched arrows; when they group together, your spine is correct.