Spoke
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A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface.
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Spokes can be made of wood or metal. Some types of wheel have removable spokes which can be replaced individually if they break or bend. These include bicycle and wheelchair wheels.
The original type of spoked wheel with wooden, fixed spokes was used for horse drawn carriages. For use in bicycles, such wheels proved too heavy, so wheels with spokes made of tensioned, adjustable metal wires were introduced. Although the tension-spoked wheel appears to work in a completely different way to the wagon wheel, it doesn't: only the bottom few spokes carry the load at any given time, and do so by reducing in tension in the same way that only the bottom few spokes of a wooden wagon wheel are in compression at any time. Constructing a tension-spoked wheel from its constituent parts is called wheelbuilding and requires some experience for a strong and long-lasting end product.
With the development of the automobile, these wire wheels, with their excellent weight to strength ratio, soon became popular for light vehicles. The wire wheels were generally soon replaced by the less expensive metal disc wheel, but wire wheels remained popular for sports cars up to the 1960s.
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