Find the correct arrow spine (stiffness) for your bow setup. Spine selection is critical for accuracy — too stiff or too flexible causes erratic flight.
Laboratory measurement — deflection (in thousandths of inch) of an arrow under a 1.94 lb weight at its centre, supported at both ends (28" span). Lower number = stiffer. e.g., 340 spine is stiffer than 500.
How an arrow actually behaves when shot — affected by bow weight, draw length, arrow length, point weight, and release type. Static spine is the starting point; dynamic spine determines real-world tuning.
In recurve/traditional shooting, the arrow must flex around the bow riser. The spine must be right to ensure the arrow returns to centre-line after clearing the bow. Too stiff or too weak causes consistent miss to one side.
Shorter arrow, lighter point, mechanical release, heavier draw weight — all effectively stiffen the arrow's dynamic spine. Use a stiffer spine (lower number) if you increase any of these.
Longer arrow, heavier point, finger release, lighter draw weight — effectively weaken the dynamic spine. Go to a weaker spine (higher number) in these cases.
Weight of arrow shaft per inch of length. Total arrow weight = (GPI × length) + nock + insert + point + fletching. Heavier arrows penetrate better; lighter arrows are faster. FOC (Front of Centre) balance also matters.