We've all flexed our carbon arrows, checking for breakage and marveling at the resiliency of this miracle fiber that allows us to shoot straight and deliver killing power with strong, lightweight shafts.
But how many bowhunters really understand how much flexing and bending our shafts are enduring, even when we shoot such inconsequential targets as apples?
Check out this video to see just how much shock and resistance a typical carbon arrow meets when it encounters a Red Delicious.
There's nothing fancy about this experiment. The shaft is a Carbon Express Blue Streak 350, tipped with a 125-grain G5 Montec broadhead and shot from a Bowtech Invasion tuned to 63 pounds at 29-inch draw length. We shot the apple at 15 yards, so you can figure the arrow was traveling somewhere in the 280fps range.
What is remarkable about this high-speed video is that it reveals the amount of flex that this shaft absorbs as it follows the broadhead through the apple. As we shot this video, it occurred to me that few bowhunters really understand the importance of spine in their shafts. Most of us know enough to be dangerous: that heavier bows require shafts with stiffer spines, and that lighter bows can handle shafts with lighter spines.
Most literature devoted to shaft deformation is focused on target shooting: Too much spine causes an arrow (from a right-handed shooter) to hit to the left of the target. Too little spine causes the arrow to "bend" around the riser and hit to the right of the bull.
But not enough time is spent discussing how flex matters when a shaft meets resistance. In this case it was an apple, but after watching this video, imagine the sort of contortions you require of an arrow when it strikes a deer, or an elk. Your shaft has to be strong enough to penetrate, but limber enough to snake around ribs and shoulders and other impediments to a pass-through shot.
So spend some time figuring out the correct spine to allow you to hit the bullseye consistently, but also have the flexibility to meet, and deflect, the resistance of your target.
