Wheelbuilding Wheelbuilding Wheelbuilding is the process of assembling wire wheels (generally a bicycle wheel, but including wheelchairs, and some cars). The components of a wire wheel are the rim, spokes, nipples, and hub. The wheelwright must ensure that the wheel is true in two ways: lateral (sideways wobble) and radial (roundness/hop). The wheel also needs to be properly dished if applicable (the left and right sides of the rear wheel differ, the drive-side spokes requiring higher tension). Spokes should have no residual twist (windup) from tightening the nipples. The spokes may be "stress relieved", i.e. subjected to a greater tension during
Reaction wheel temporary changes in its speed result in small changes in angle. The wheels therefore permit very precise changes in a spacecraft's attitude. For this reason, reaction wheels are often used to aim spacecraft carrying cameras or telescopes. Over time, reaction wheels may build up enough stored momentum to exceed the maximum speed of the wheel, called saturation, which will need to be cancelled. Designers therefore supplement reaction wheel systems with other attitude control mechanisms. In the presence of a magnetic field (as in low Earth orbit), a spacecraft can employ magnetorquers (better known as torque rods) to transfer angular momentum