Motorcycle wheel wheels are predominantly made from an aluminium-alloy, but can also be made from more-exotic materials, such as magnesium content alloy or carbon fibre. The first commercial motorcycles were built like bicycles, with wire wheels as bicycles had traditionally been fitted with. The Steffey motorcycle in 1902, essentially a bicycle with a two-stroke engine attached, used wooden rims with wire spokes. This style of wheel evolved into a stouter motorcycle-specific wheel, still with spokes, up to the 1960s and beyond. In April, 1922, Borrani started production of motorcycle wheels with an aluminium rim. Although cast wheels had already been used on
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