A player stringing a crossbow with a Crossbow string.
A Crossbow string is used in the Fletching skill to create crossbows. It is created by using sinew or tree roots (except Magic roots) with a spinning wheel, requiring level 10 Crafting and grants a player 15 Crafting experience.
Crossbow strings are seldom made by players. Bow strings require the same Crafting level and give the same amount of experience, and are often in higher demand. Collecting the material is also much quicker, and it takes up to two steps to produce a crossbow string versus only one to make a bowstring.