Most adult bikes today are equipped with quick release (QR) wheel retention devices on both wheels. QR's are very reliable in keeping the wheels securely attached to the bike, provided you know how to use them correctly. And, despite the fact the QR's have been in wide use for several decades, many people are still unfamiliar with how they work. Please, do not ride your bike without knowing how to use the quick release.
The QR is not simply a wing-nut to be twisted as tight as possible. If you are using it that way, your wheel could come off your bike while you are riding. I probably do not need to go into any potential gory details at this point.
The QR skewer has four parts (see diagram). A lever (A), a cap that the lever goes into containing either an exposed or concealed CAM mechanism, a shaft, which goes through the hollow center of the hub, and a threaded adjusting nut on the opposite side from the lever (B). To make sure the QR is properly closed, follow these steps:
* Closing the lever should require very firm pressure using the heel of your hand. If you can easily close it with a couple of fingers, it is not tight enough. Open the QR lever and tighten the adjusting nut a bit more. Then close the QR lever again.