Wire wheel situation is debated. Some authors conclude from this that the hub "stands" on those spokes immediately below it that experience a reduction in tension, even though the spokes below the hub exert no upward force on the hub and can be replaced by chains without much changing the physics of the wheel. Other authors conclude that the hub "hangs" from those spokes above it that exert an upward force on the hub, and that have higher tension than the spokes below the hub, which pull down on the hub. Despite being composed of thin and relatively flexible spokes, wire wheels
Idler-wheel sees this on true tracked vehicles, however, as the second drive wheel is redundant. Idler-wheel An idler-wheel is wheel which serves only to transmit rotation from one shaft to another, in applications where it is undesirable to connect them directly. For example, connecting a motor to the platter of a phonograph, or the crankshaft-to-camshaft gear train of an automobile. Because it does no work itself, it is called an "idler". An idler-wheel may be used as part of a friction drive mechanism. For example, to connect a metal motor shaft to a metal platter without gear noise, early phonographs used