Archers paradox is a term used to describe the bending of an arrow shaft upon release from the drawn string. Specifically, the shaft bends in an arc around the handle or riser of the bow. It is a misconception that “centershot” bows, (those whose arrow shelf is cut deeply into the riser so that the arrow “rests” in the bows true center) do not experience bending of the arrow upon release from the string. The fact is, that the arrow is beginning its flight from a point of rest (at full draw) and upon string release a great force is placed upon the nock thus commencing the motion of the arrow. The laws of physics determine that an object at rest (the arrow) would like to remain at rest. In this case, the string is transferring energy from the bow limbs to the arrow, “forcing” its movement. This stresses the arrow causing it to flex. If the arrow is shot from an arrow rest off the side of the bow rather than the bow’s true center the arrow will tend to flex around the handle (riser). Now that we know that all arrows flex upon shooting, the role of arrow spine comes into play. The arrow spine or “spine weight” refers to the stiffness or “flexibility” of the arrow. An arrow that is underspined is too limber. An overspined arrow is too stiff, while a properly spined arrow is just right. The properly spined arrow still bends upon release however it bends the correct amount so that it can recover and continue in a straight arc to the intended target.
From a practical standpoint what matters is that an underspined arrow will tend to fly to the right when released from a right handed bow. This is because it is too limber and therefore excessively bends around the bow handle. An overspined arrow is too stiff and therefore doesn’t bend enough around the handle but rather glances off the riser and flies to the left. In addition to flying left or right an improperly spined arrow will wobble from side to side. This is usually referred to as “fishtailing”.
A word about arrow rests. Most selfbows, many longbows, and some recurves are not centershot but rather shot off the side of the riser. These bows tend to need a lighter spined (more limber) arrow. This is because it is necessary to have the shaft flex around the handle to help the arrow achieve the center of the bow. Some bows, usually recurves are truly centershot. Because of this, very little arrow flexibility is desired since the arrow is initially leaving the bows center. The important point is that center shot bows at the same poundage will usually prefer a heavier spined arrow then a non centershot bow at the identical poundage.
Archers paradox seems technical but probably receives more attention then it deserves. All arrows whether wooden, aluminum, carbon, or whatever suffer from archers paradox and should be properly spined to match your individual bow. From a practical stand point, most traditional bows will accurately shoot a variety of spine weights. Assuming that you select a spine weight within ten pounds +/- what is optimum for your bow, with a little practice your arrows will hit the mark. Whenever we switch bows, or make new arrows, the target impact may be several inches to the right or left but after thirty or forty shots the instinctive mind compensates and the arrows fly true. A truly instinctive archer, with a little practice, can shoot any type of traditional bow that has reasonably matched arrows. For a chart of recommended arrow spines of different bow weights please refer to the article entitled Determining Arrow Spine Weight. If you build yourself new arrows, do not be surprised if your initial groups are several inches to the right or left of the target. If your arrows are not visibly “fishtailing” then most likely after thirty to forty shots your instinctive abilities will adjust your arrow flight.
It is important to remember that wood, whether in our bows or in our arrows is not perfect. As traditional archers we accept that. Although traditionalists strive for perfection, we must always remain within the limits of traditional equipment and its abilities. It is nontraditional, to seek technological advancements in our bows and arrows, which enable us to surpass traditional limitations.