Spoke nipple

A spoke nipple holds a bicycle wheel's rim to each spoke.

The spoke nipple is a headed cylinder with threading on the inside through part of its length (there is an unthreaded lead-in nearest the "flats"). Traditionally, the nipples fit in holes in the rim, so that the head of the nipple is on the outermost part of the rim, while the other end of the nipple points inwards towards the hub. Many different types of nipples are now available, including internal nipples that sit entirely within the rim and can only be adjusted by removing the tire, as well as externally threaded nipples that thread into the rim (such as those used by Mavic Ksyriums). The threading grasps the spoke, so turning it increases or decreases tension in the spoke and influences the position of the hub relative to the rim.