A quick release skewer is a mechanism for attaching a wheel to a bicycle. It consists of a rod threaded on one end and with a lever operated cam assembly on the other. The rod is inserted into the hollow axle of the wheel, a nut is threaded on, and the lever is closed to tighten the cam and secure the wheel to the fork. Wheels equipped with quick release mechanisms can be removed from the bicycle frame and replaced without using tools by opening and closing the cam lever, thus more quickly than wheels with solid axles and hex nuts. On the negative side, a quick-release hub renders a wheel more vulnerable to theft. Also, care must be taken to ensure that the mechanism is properly tightened.
Similar quick-release mechanisms are also used to operate seatpost clamps, and the collapsing stem of folding bicycles and kick scooters.
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The mechanism was invented in 1927 by Tullio Campagnolo, an Italian bicycle racer. He was frustrated when he needed to repair a flat tire during a race. The weather had turned cold, and his hands were numb, so he could not operate the wingnuts which retained the wheel. He had been well-placed prior to the puncture, but lost valuable time. Another Campagnolo invention that made use of the quick-release mechanism was the Cambio Corsa, a multi-gear changing system consisting of a rear wheel quick-release lever with a mechanical extension that placed the lever itself near the bicycle's saddle, combined with a fork that served as a primitive version of a rear derailleur (without idler pulleys to take up slack), that also had a control lever near the bicycle saddle. This innovation enabled bicycle riders quickly to change gears while in motion by releasing the axle, moving the rear wheel slightly forward by applying tension to the chain, actuating the fork to change to a larger sprocket, and tightening the quick release again; or else releasing the axle, actuating the fork to change to a smaller sprocket, moving the wheel slightly rearward by braking, and tightening the quick release again. The quick-release mechanism, along with other innovations and high standards of manufacture, enabled Campagnolo to become a leading road cycling and track cycling component manufacturer.
Quick releases tend not to be used on certain types of bicycles, such as utility bicycles (with a single speed or hub gears) or track bicycles, partly because of tradition and partly because there is less need for quick removal of wheels without using tools.[1]
Quick releases are sometimes recommended against with the use of disk brakes because of the need for the axle attachment to withstand braking forces.[2][3]
Over the years quick release mechanisms have been adopted as the primary wheel release devices by the average rider. However, as Sheldon Brown (bicycle mechanic) notes[4] this change has come with some difficulty:
"Because some bicycle users are competent enough to remove their front wheels but not competent enough to secure them properly when they reinstall them, virtually all new bike purchasers have been deprived of the handy function of quick-release front wheels. This has been done by encumbering fork ends with extra hardware, ridges or lumps that keep the wheel sort-of attached even if it has been installed by someone who doesn't know what he or she is doing. Unfortunately, this means that the quick-release mechanism must be re-adjusted each time it is used, seriously slowing down the operation. Since this extra stuff was installed as a defense against frivolous lawsuits by ambulance-chasing shysters, the extra bumps are sometimes known as "lawyer lips" or "lawyer tabs." As "lawyer lips" have become the norm, they have gradually become more important than they originally were, for two reasons: * The prevalence of these secondary rentention systems in front, and vertical dropouts in the rear has caused the proliferation of inferior skewer designs that are cheaper to manufacture, but much less secure than traditional skewers. See my Article on Quick Release Skewers. * The introduction of disc brakes has caused increased vulnerability of the front axle and skewer, due to the disc brake applying an ejection force that tends to pull the axle out of the fork."[5]
The debate over quick release use as illustrated by Brown, has become a national issue due to several lawsuits brought on by various people including a group of mothers who claim their children were injured due to innocently incorrect use of quick releases.[6]
The quick-release levers are usually on the left side of the bike, though some prefer to have them on the right if a disc brake is on the left.[7][8] Mountain bikers often prefer to point the lever aft, lest it catch on undergrowth and be pulled open.[9]
Locking skewers are available without handles or with specialty removable handles in order to deter wheel theft.
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