Quick release mechanisms have been employed in bicycle technology since the early days. The most common application is quick release front wheels, making it much easier to put a bike in a small car.
Quick-release mechanisms used to secure bicycle wheels are called “quick-release skewers.”
Between the 1950s and 1970s, wingnuts were often used instead of ordinary axle nuts to secure wheels without the need for tools. However, this turned out to be a poor idea. It is difficult to turn a short wingnut sufficiently to properly secure a wheel.
Front wheel safety washer or ‘safety tab’
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A better solution is a cam mechanism that can be tightened very securely even though the lever is short.
Photo by Andrew Dressel
And that’s how a quick release wheel works. It has a thin threaded rod that passes through a hollow wheel axle. One end of the rod is threaded and holds a nut that can be turned by hand. The other has a cam-action lever. This arrangement was invented in 1930 by Italian bike racer and manufacturer Tullio Campagnolo.
Some people don’t understand these mechanisms, and try to screw the lever side very tight, without realizing the functionality of the cam. The proper way to do it is to turn the nut until the mechanism is nearly tight. Then operate the lever so that the cam finishes the job of securing the wheel. You may need to adjust the nut and operate the lever several times to find an adjustment in which the cam is secure, yet opening and closing the lever is still easy enough.
Quick release mechanisms are also found in place of ordinary seat pins, folding bike frames, and on some handlebar stems.
Old style quick-release seat pin (threaded, not cam-action)
By Conollyb (Own work) [CC BY-SA 3.0, via Wikimedia Commons