How does a rear derailleur work? Let`s find out by reading this guide below. To keep the chain stretched, the derailleur usually adjusts its location to maintain tension in the chain, regardless of the equipment you are using. The derailleur moves depending on where the chain goes. Depending on the gear used, the chain can move to the largest sprocket or to the smallest sprocket. A rear derailleur is a bicycle transmission system with variable speed ratio consisting of a chain, several sprockets of different sizes and a mechanism for moving the chain from one sprocket to another. [1] Since a rear derailleur is an integral part of your bike, it is important to know the different parts of the rear derailleur and how they work. Bicycle circuits are divided into different parts, which also have specific functions: the most important innovations since the 1990s have been the transition from friction to indexed gear change and the gradual increase in the number of speeds. When changing gears by friction, a lever directly controls the infinitely variable position of the derailleur. To change gears, the pilot first moves the lever so far that the chain can jump to the next sprocket, and then slightly adjusts the lever to center the chain on that sprocket. An indexed gear lever has a locking or ratchet mechanism that stops the gear lever and therefore the cable and rear derailleur after traveling a certain distance with each push or pull. Indexed gear levers must be recalibrated if the cables stretch and the parts are damaged or replaced. 10-speed rear cassettes appeared on racing bikes in 2000 and 11-speed cassettes in 2009.
Most current mountain bikes have both. Many modern high-end mountain bikes have started using only a chain drive, with the industry constantly increasing the number of rear speeds, as evidenced by SRAM`s Eagle Group packages (1 x 12) and Rotor`s recent 1 x 13 powertrain. [12] Most road bikes have two trays, and touring bikes usually have three. Gear levers that apply one convention are generally not compatible with derailleurs that use another, although there are exceptions[24] and adapters are available. [25] Indexing is another important method for derailleurs. It is the derailleur that moves when triggered by switching the cable. Indexing is a crucial process that allows your bike to shift smoothly and smoothly. Due to the possibility of the chain passing in front of the smaller inner tray, especially if the inner tray is very small, even on motorcycles adjusted by professional racing mechanics, and the problems that such malfunctions can cause, there is a small aftermarket for auxiliary products, called chain deflectors, to prevent them from occurring. [27] [28] [29] A clamp around the seat tube, under the derailleur, and at least one is attached to the derailleur support. Tighten the cable in the rear derailleur as usual, then slide the bike onto the largest gear or tray and let it sit for about ten minutes.
The rear derailleur helps the chain convert the energy released by cyclists during pedaling. It modulates this input and transmits it to an ideal output, which is manifested by distance and speed. The derailleur and switchgear of the bike work on the same principle. Therefore, it is important to understand their functionality in order to know the overall operation of a bike. What is a rear derailleur? The rear derailleur of the bike has two basic functions: to keep the chain stretched and to move. It is intentionally positioned in an area where the chain decreases from time to time. The derailleur is often referred to as a chain tensioner because of this special task. A bicycle chain switchgear is a crucial part of a bicycle machine. It directly affects the speed and autonomy of the driver.
It is a guiding mechanism that allows cyclists to change the chain from one sprocket to another. ATVs need an efficient and reliable derailleur to operate more efficiently. The rear derailleur of the bike acts as a chain tensioner by moving from the smaller sprockets to the larger sprocket. In this process, your bike moves seamlessly without putting too much pressure on the bike chain. Without a derailleur, you could end up damaging the chain and pedaling too much effort. In our example, the bike manufacturer may have a step-by-step video for troubleshooting, or a content creator with a passion for cycling may have a “how” for a broken rear derailleur. The distance between the upper and lower pulleys of a rear derailleur is called the length of the cage. The length of the cage, combined with the size of the pulley, determines the ability of a derailleur to accommodate the chain buffers. The length of the cage determines the total capacity of the derailleur, that is, the difference in size between the largest and smallest trays and the difference in size between the largest and smallest sprockets in the gear together. A larger sum requires a longer cage length. Typical cross-country ski mountain bikes with three front trays use a long cage switchgear.
A road bike with only two front trays and narrow-ratio sprockets can be used with short or long cage chain switchgear, but works best with a short cage. Normal or rapidly rising low rear derailleurs bring the chain back to the largest sprocket of the cassette when no cable voltage is applied. While this was once a common design for rear derailleurs, today it is relatively unusual. [16] In mountain biking and off-road cycling, the most critical gear changes occur on uphill sections, where cyclists have to overcome difficult obstacles and curves while pedaling under heavy loads. This type of derailleur offers an advantage over high-level rear derailleurs, as gear changes are made on lower speeds in the direction of the loaded spring, which facilitates these shift operations when pedaling at high load. The rear derailleurs use a cage equipped with two pulleys. The lower pulley pulls backwards to load the lower part of the chain. It is called a tension pulley or “T-pulley” for short. The upper pulley guides the chain to the sprockets. It is called a guide pulley or “Gâ pulley” for short. Good to know As part of your beginner triathlon training, you should consider it imperative to master the basic skills of bike maintenance, such as changing a flat tire and making minor derailleur adjustments. Then came the chain drives that allowed you to use wheels of the same size, and the free wheels that allowed you to navigate, and the derailleurs that allowed you to change gears.
When you switch to lower gears, the chain is usually automatically transferred to the larger sprockets. During this process, the front derailleur of the bike moves inwards and upwards while following the chain control and goes to the selected sprocket. Once the tension in the chain increases, note that the pulley “T” moves away from the pulley “G”. There are at least two methods used by rear derailleurs to maintain the appropriate distance between the top jockey wheel and the rear sprockets while the rear derailleur moves between the large sprockets and small sprockets. One method used by Shimano is to use the tension of the chain to rotate the cage. This has the advantage that most sets of sprockets are used if the chain is of the right length. One disadvantage is that the quick transition from small sprockets to large sprockets on multiple sprockets can cause the cage to hit the sprockets at the same time before the chain moves to the larger sprockets and rotates the cage as needed. Another method used by SRAM is to design the distance in the parallelogram mechanism of the derailleur itself. The advantage is that no quick and multi-pinion change can cause the cage to hit the sprockets. The downside is that there are limited options for sprocket sizes that can be used with a particular rear derailleur. An electronic shift system allows the driver to switch with electronic switches instead of conventional control levers.