What does the stiffness of the arrow shaft refer to?

The stiffness of the arrow shaft is referred to as the spine. Specifically, the spine of an arrow measures how much the shaft will flex when a force is applied, typically when the arrow is drawn back on a bow. This characteristic is crucial because it influences the arrow's flight trajectory; a properly spined arrow will provide optimal accuracy and distance.

Choosing the correct spine rating is vital for achieving the best performance from a bow, as it helps in determining how well an arrow can maintain its path upon release. A shaft that is too stiff may not flex properly, leading to erratic flight, while one that is too limber might not deliver the energy efficiently, decreasing range and precision. Understanding the concept of spine is essential for archers in selecting the right arrows for their specific bow setup, taking into account draw weight and personal shooting style.