this blog post they thoughtfully explain the premise behind and steps needed to properly tru a typical bicycle wheel.

The typical bicycle wheel is composed of a rim suspended with tensioned spokes around a center hub. Each spoke pulls on a section of rim. Spokes coming from the right side hub flange pull the rim to the right. Spokes coming from the left side hub flange pull the rim to the left. Spokes attached at the rim are then offset in a left-right-left-right pattern to counter the pull of the other side. Having all the spokes tight with fairly even tension makes the wheel true and strong. Changes to spoke tension will pull on the rim and affect its true. This process is called “truing”.

Truing is occasionally needed to keep the rim running straight as it spins between the brake pads. Spoke tension is adjusted by tightening or loosening a threaded nut, called the nipple, at the end of the spoke. Spoke threads typically use right-hand threads. Although a common phrase among mechanics is to “tighten the spokes”, it is the nipple that is turned, not the spokes.

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