弦是射箭配備中不可或缺的主要器材之一，其主要功能是當選手拉弦放箭時，可把弓臂的彈性能轉化成動能將箭彈出。弦的製作雖依弓磅數及長度以弦線纏繞而成，但股數及長度並無標準的規格。本研究主要目的：是在探討一、不同弦股數及在不同中央弦距設定下，對射箭拉力值的影響。二、射箭者常因故在拉滿弓後而未能將箭射出，弦是否有殘留的能量儲存在弓臂中，進而改變下一次射箭的拉力值。方法：本研究是以20股及12股的弦，利用固定射箭機器平台上精密導螺桿之轉數，精確固定每一次拉弦的力量，並量測其拉力值。結果：發現兩組不同股數的弦，不論在各不同中央弦距設定下或箭未射出時，兩組弦其拉力的差值皆相當細微。結論：一、不論是20股或12股的弦後拉至28英吋時，其中央弦距設定越長者，所需的拉力會越大。二、兩組不同股數的弦，當其後拉至25及28英吋而未將箭射出，如再次拉弦至相同位置，其拉力值並未改變。

String is an important component of archery equipment to generate the elastic energy by the pulling action of archers. Elastic energy is converted as the kinematic energy of arrow after the releasing the string. Normally the string is circulated around two ends of bow limb to reduce distance between these two ends for storing the desired energy of the arrow. There is no formal standard to define the length between two ends and number of strings for installing string. The first objective of the paper is that for the same bow and length of string, how various numbers of strings as well as the spacing between the string and the anchor point affect the pulling force need be verified. The second objective is whether the failure of releasing arrow after fully pulling will result in undesired residue energy to affect the elastic energy is also needed to be studied. We utilize the precision machine to accurately control the pulling distance and to measure the associated pulling force. Based on 12 and 20 numbers of strings settings, it indicates that pulling forces are almost the same regardless of different string number and spacing settings. However, for both numbers of strings settings, we find that (1) Pulling force at 28 inches pulling distance will increase when the spacing settings increase. (2) Failure of releasing arrow after fully pulling to be 25 or 28 inches does not significantly affect the pulling force.