Quick release
Clamping devices are referred to as quick release or quick release devices, which can be released or fixed (clamped) quickly and usually without tools by hand .
They are very common in machine tools for holding workpieces during machining or for securing closures on containers, as well as on bicycle parts such as the wheels or seat posts on the frame or fork.
Quick release for wheels on the bike
history
The quick release was invented by Tullio Campagnolo in 1930 and a patent has been applied for. He had lost valuable time in a race in 1927 because of changing a wheel using wing nuts; Back then this was the only way to change the gear ratio by turning the rear wheel. In the patent, the quick releases were still called “gearboxes for cycling”.
functionality
Quick releases on wheels make it possible to remove and install them very quickly. To remove, in addition to operating the quick release, an existing rim brake must be released and the derailleur of the derailleur must be pulled back on the rear wheel. With some hub gears, dismantling is a little more difficult. Torque arms and shift cables often prevent the bike from being removed quickly.
A quick release clamps the axle of the wheel in the downwardly open dropouts of the frame and front fork and thus replaces other clamping devices such as hex nuts or wing nuts to secure the wheel. With regular cone axles, the lock nuts of the bearing cones lie against the inner surface of the dropout, the stubs of the hollow axle protruding approx. 4 mm above the clamping surface on both sides find their place in the semicircular recesses of the dropouts.
An axial clamping force is exerted on the outer surfaces of the dropouts by a steel tie rod with a diameter of 5 mm leading through the hollow bored hub axle (“hollow axle”), the “clamping axle”, which leads to sufficient locking of the hub axle in the frame and fork. A quick release usually works with an eccentric , which is operated by a small hand lever. The high tensile stress causes correspondingly high frictional forces, so that the lever does not come loose by itself. With a very easy-to-use quick release, the eccentric is swiveled slightly beyond the maximum deflection (eccentric dead center) before it rests on the frame or fork, so that it is fixed in the closed position by the tension of the clamping axle. The lock nut of the quick release can be adjusted by hand on the M5 thread of the clamping axis in the open state in order to preset the entire device so that there is sufficient tension at the end of the lever path. As a rule, the operating levers are on the left side of the bike, the adjustable lock nuts on the right.
The quality is measured primarily by the clamping effect. Inexpensive models sometimes use plastic rings, which can be a safety risk in the case of sporty driving or high loads.
service
To remove the wheel, the lever of the quick release is opened, which sometimes requires great force. The nut opposite the lever must then usually be held in place and the lever with the quick release axle swung around a few turns counterclockwise so that the wheel can be lifted out of the dropout.
When installing, the lever is swung clockwise after inserting the impeller (hold the nut on the opposite side). The correct presetting has been achieved when the lever can then be turned around without any effort until it is at an angle of 90 degrees to the level of the impeller. Finally, it is completely laid around with force until it lies as flat as possible on the frame or fork. It should be pointed backwards so that it does not come off unnoticed if you hit an obstacle with the bike and so that no cords, leashes, wires or even items of clothing are dragged along in dense (pedestrian) traffic.
Modern sports bikes with derailleur gears usually have vertical rear dropouts that do not require the wheels to be aligned. Bicycles with hub gears as well as many simple and some racing or touring bikes have sloping or horizontal dropouts at the rear so that the chain tension can be adjusted by moving the rear wheel. Adjustment screws, which are screwed into the dropout or, after the wheel has been inserted, chain tensioners pushed over the axle like a washer, ensure precise alignment.
restrictions
Many front forks have locking lips in the lower area of the dropout, which prevent the wheel from falling out, even if the clamping lever is not closed. However, due to this safety device, the lock nut has to be screwed on a few turns in order to be able to remove the wheel from the fork, which partially destroys the time saved by the quick release when changing the wheel.
Powerful disc brakes require special care when installing the quick release on the front wheel. The brake caliper attached behind the fork creates a considerable resulting force on the axle clamp in the direction of the downwardly open dropout during heavy braking , which can exceed the clamping force exerted by the quick release and can cause the hub to slip in the clamp and thus damage one safety-critical component leads. In the event of a break in the tensioning axle, the axle would be levered downwards out of the dropout when the brakes were applied, which would not be so likely with the balance of forces in a rim brake. For this reason, thru axles have recently been used more and more on disc-braked bicycles instead of quick-release levers in order to overcome this shortcoming.
theft
The quick operation makes it easy for thieves to steal components of the bike in seconds. This is why quick release axles are offered that can only be opened with special keys. Casual thieves are deterred, but specialists can quickly remove these types of security using simple means.
See also
literature
- Paolo Faccinetti, Guido P. Rubino: Campagnolo - a company makes bicycle history ; Delius Klasing Moby Dick; 1st edition 2009; ISBN 978-3-7688-5275-3
- Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production . 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld, 1999, ISBN 3-87073-131-1
Web links
- Bicycle Quick-Releases , article about quick releases on the Sheldon Brown site , in English
Individual evidence
- ↑ History of Campagnolo on fahrradmonteur.de
- ↑ Axle fastening when setting derailleur gears on Fahrradmonteur.de