Types of bike transmissions
A bike drivetrain can be:
- Straight, when the drive wheel and pedals are attached directly, without the use of a chain system. This transmission is found on penny-farthing, monocycles (with one wheel), tricycles for children.
- Cogwheel, which uses gears with teeth.
- Shaft, which uses shafts to transmit torque.
- Belt. Belts are used here, which, unlike chains, do not require lubrication.
- Hydraulic. A hydraulic system is used, not a mechanical one.
- In the form of a planetary hub, consisting of a large number of parts and resembling a car gearbox.
- Combined, which is a hybrid of two types of transmissions for a bicycle at once: external and internal (planetary).
Switch with internal mechanism
In internal derailleurs, the shift mechanism is located inside the rear hub. Such a sleeve is called planetary. The appearance of the bike with it resembles a fixed: one large star in front and one small one in the back. As a rule, the rear brake of the bicycle is also located in the planetary hub. The number of shifted gears in the planetary hub can be from 3 to 14. They are installed mainly on road, city, walking bicycles.
The switch based on planetary bushings has a long service life, due to the fact that the mechanism itself is closed in the housing from external influences and has constant lubrication. Of the advantages, it is also worth noting the built-in brake and the ability to switch without pedaling. There are few shortcomings, but they are significant: additional force must be applied due to friction of the units, large weight of the device, difficult repair, high price.
How to install a derailleur hanger and rear derailleur on a mountain bike | How to build a MTB
Gear ratio of the drive of the switch of speeds
Switch Drive Ratio. The ratio of the switch movement to the corresponding cable movement. Shimano uses a 2: 1, SRAM 1: 1 ratio in its shifters and rear derailleurs, which is why the rear derailleurs are not interchangeable (although SRAM makes some shifters compatible with Shimano derailleurs). Although SRAM engineers claim that their 1: 1 system provides better performance in tough conditions and with dirty cables, there has been no practical evidence of this. And according to cyclists, SRAM derailleurs work harder than Shimano.
The situation is now further complicated by the introduction of ten-speed drivetrains from Shimano and SRAM. Neither are compatible with 9-speed counterparts from the same firm, but SRAM’s 9-speed drivetrain is compatible with Shimano’s 10-speed Dyna-Sys mountain range. However, Shimano’s 10-speed road shifters and derailleurs are still designed for classic cable travel (2: 1), so there are naturally 10-speed straight bar “hybrid” shifters that are compatible with classic derailleurs (R-Series).
External Mechanism Switch
Most often, external derailleurs are used on bicycles: front and rear.
Front. His job is to move the chain from one star to another. The parallelogram mechanism moves the frame through which the chain runs. When switching to a different speed, the frame moves and is located above the required sprocket, after which the chain also jumps to it. The front derailleurs are distinguished by their characteristics:
By the method of attachment to the frame: on clamps to the seat tube or to the frame carriage. 2. By the method of fastening the cable: top or bottom. 3. By the angle of installation on the frame.
Rear. The principle of operation and function of the rear derailleur is the same as that of the front derailleur to transfer the chain from one chainring to another. But unlike the front, where there are a maximum of 3 stars, on the back their number on the cassette reaches 11. Its additional function is chain tensioning. According to their characteristics, the rear ones are divided into types:
By the type of bike on which they are installed: separate systems are produced for road and mountain bikes 2. Step by step: the size of the working part of the cable from the smallest sprocket to the larger one. 3. By the maximum size of the largest star. 4. By capacity: the difference between the size of the largest and smallest stars in the cassette. 5. By the type of attachment: on a removable or non-removable cock. 6. By the type of traction: with a straight traction, the cable throws the chain to the large stars, and the spring to the smaller ones. The reverse is true for derailleurs.
The external mechanism switches are simple in structure, light in weight, low in price, and large in gear range. Disadvantages: rapid chain wear due to shifting when shifting, frequent maintenance cleaning, lubricating and adjusting, more likely to break when falling, the speed can only be shifted while driving.
Rear derailleur frame length
There are three standard frame lengths that define derailleur capacitance, the range of gear ratios that the rear derailleur can handle. Longer frame length allows the switch to choose a larger chain slack. more “capacity”.
To put it another way, “derailleur capacitance” is the total difference between the largest and smallest stars in the cassette and the system that can be operated by the derailleur without sagging or binding in the chain. For example, if the bike has an 11-32T cassette and a 22-32-44T system, then the minimum allowable capacity of the rear derailleur is calculated as follows: (32-11) (44-22) = 43T.
If you install a speed selector whose frame is shorter than required, then the chain will be loose on the front small and rear small sprockets (if the chain length is selected correctly).
Installing a rear derailleur with a too long frame will not affect derailleur performance, but it will add weight and risk the derailleur frame hitting an obstacle. Some cyclists deliberately choose a shorter frame to avoid hitting an obstacle, but whether this makes sense is not yet clear.
The exact values of the capacitance of the rear derailleurs can be found in the catalogs of the manufacturers, but we will indicate an approximate rule for choosing the frame length:
How To Install & Adjust A Front Derailleur
- short frame: MTB single system (extreme bikes), road bikes with a double system;
- middle frame: MTB dual system (2×9, 2×8), road bikes with triple system (or dual system and mountain cassette);
- long frame: MTB with triple system (as well as 2×10 with cassettes of type 11-36) and other options.
Features and varieties
The Shimano product line includes a large number of derailleur categories depending on their purpose:
The procedure for adjusting gear shifting on TM Shimano bicycles
All modern sports bikes are built with multi-speed bikes. In order for them to work fully, the system is equipped with special spreaders. True, they should be adjusted periodically. Special attention should be paid to the adjustment of the gearshift on the Shimano bicycle, which is popular with athletes. Difficulties with this will not arise if you carefully study the instructions.
Bicycle front derailleur
The transition to the setting of this mechanism is possible only when the rear derailleur is set. This feature is important to take into account before starting work. The figure shows the switch (round, black).
Leave the chain on the middle sprocket of the front block and place it on the large sprocket in the rear block. If chain friction is observed, re-engage adjuster L. To adjust stop H, the chain moves to the largest sprocket at the front and smallest at the back. The adjuster will help to position the chain in the optimal position without friction and excessive tension on the chain. At the end of the work, be sure to check the quality of its implementation.
Take the survey
The following types of mechanisms are professional:
- Shimano XTR, Deore XT. The device has a high degree of reliability, but belongs to the category of expensive.
- Saint. A professional, reliable variety that differs from the previous ones in the raw materials used. Composite materials are used in its manufacture. Thus, it is possible to reduce the weight of the components.
- Hone, Deore LX. Top class products, but more affordable than other professional movements.
Among sports equipment, the Deore bike’s derailleur system deserves attention. This model belongs to the initial group. Parts with reduced weight and maximum strength are used in the manufacture.
The Alivio model is also considered to be sports. It is a cross between amateur and professional devices. Often, preference is given to it, due to the small mass of parts.
XTR Deore XT Saint Hone Deore LX
Amateur gears can be used to change gears:
- Acera. Able to withstand heavy loads. Often, beginners use the mechanism incorrectly, so manufacturers have made it unpretentious. When adjusting the gear shifting on a Shimano bike, this does not require high precision.
- Altus. An affordable device for beginner cyclists. Designed for quiet walks in parks and city streets without heavy loads and frequent speed changes.
- Shimano Tourney. The mechanism is not designed for extreme driving. Shimano Tourney often has unexpected situations.
Shimano derailleur settings, regardless of variety, follow the same setup. All mechanisms function the same, are considered interchangeable.
Acera Altus Shimano Tourney
How to adjust the speed switch on a bike
Having become the happy owner of a bike, you should be prepared for the fact that over time you will have to carry out basic maintenance of the bike yourself. Of course, if we are talking about a serious malfunction, it is best to seek help from specialists, but many manipulations can be safely performed on your own.
Correct adjustment depending on the type
Adjustment is necessary in cases where shifting speeds on the bike starts to cause problems. As a rule, such actions are carried out in such cases:
- a bike was purchased that was poorly adjusted in the sports department;
- violation of the rules for transporting a bicycle;
- vehicle mileage is large enough.
The work will need the following tools:
The front derailleur setting is significantly different from the rear derailleur setting.
There are tons of brands focused on bicycle accessories on the market today. Some of the best derailleurs are the Japanese Shimano models and the American design from Sram.
Consider the modifications and characteristics of professional Shimano switches:
- XTR variants are at the top of the line in terms of quality and price. Modifications are lightweight, used primarily on racing bikes.
- Deore, Saint, Slx. used on bicycles of various categories with 27 gears.
- Shimano LX, Dura-Ace, Hone derailleurs rank third in this line, focused on bicycles with the maximum number of speeds.
- Tourney. aggregated with 21st gear, designed for a quiet ride.
These models can be divided into two groups: for sports and recreational driving. The first category includes the following variations:
- ESP 7.0. Derailleurs are made of very durable components, designed to adjust 24 speeds.
- ESP 4,0 / 5,0. have a cost lower than that of professional counterparts, withstand up to 24 gears, focused on tourist bike models. In addition, Sram 4.0 can be equipped with cheap hybrid mountain bike designs.
- ESP 3.0. designed for walking and city devices.
The question arises, which bike derailleurs are the best? There are no fundamental differences in the regulation and functioning of different lines of controllers. For example, eight-speed modifications of Alivio, Acera, Altus can be replaced by nine-speed analogs of Deore, LX / XTR. The same can be done in reverse order.
Internal type of gearshift
This design is based on planetary bushings without the use of cassettes. There are only two stars in the transmission unit. All elements are hidden inside. As a rule, in such a mechanism there is no front derailleur on the bicycle on the handlebars.
This device is used on recreational, road, city and folding bikes. The working system is located inside the rear planetary tube. It is better to entrust the adjustment of such a switch to specialists.
Front node setting
The types of speed switches for bicycles on the handlebars are indicated above. Next, let’s look at the adjustment of the front element. The assembly consists of the following parts:
- The framework through which the chain runs.
- Spring mechanism.
- Upper and lower stop (H / L).
- Retainer and cable.
Setting up a switch consists of the following steps:
- The chain must be set at the front to the smallest sprocket, and at the back to the maximum analogue.
- Using the Allen key, loosen the cable securing screw.
- Using a screwdriver and screw L, adjust the position of the frame so that the distance from the inside to the chain is 4 mm.
- The cable is pulled and secured with a screw.
- The second sprocket is adjusted after the chain on the rear derailleur has been moved to the smallest sprocket.
- Check if the chain is catching. If such a problem exists, it is necessary to tighten the cable tighter using the shifter. The distance from the chain to the frame should be about 3 mm.
- Adjust the third sprocket with screw H. If necessary, increase the gap by pushing the frame outward.
The state-of-the-art bicycle speed selector on the handlebars offers new possibilities for optimizing riding on various road sections. On such a bike, it is much easier to perform various stunts, move along uneven and mountain tracks. The main thing is to properly configure the node in question. To do this yourself, you need to study the main parts of the mechanism, including the shift lever and transmission.
The last block includes a set of parts that allow you to take on some of the load transferred to the cyclist. It also makes it easier to climb uphill and travel on rough terrain.
How do I adjust the derailleur on my bike? First, let’s look at adjusting the rear knot. This mechanism is used on most modern bikes. It consists of the following elements:
- Frame, the length of which affects the number of gears.
- Pairs of rollers responsible for tensioning and guiding the chain.
- Parallelogram mechanism.
- High and low speed limiters.
- Adjusting screw.
- Guide wire.
Assembling the speed switch on the bicycle on the handlebar, as well as adjusting it, may be necessary when the speed does not switch, the chain jumps over the sprockets, extraneous sounds or rattling are heard when the device is operating.
The unit is adjusted as follows:
- Make sure the ESC is vertical and parallel to the bike.
- The bike should be turned over with the wheels upward to provide access to the adjusting screws.
- The chain must be lowered to the smallest sprocket using the shifting turns on the right handlebar.
- Unlock the switch by loosening the cable fixing screw.
- Using a screwdriver and adjusting screw H, adjust the chain in such a way that the sprockets on which the chain lies are located on the same mowing line.
- The cable is stretched by hand as much as possible, after which it is fixed with a screw.
- Next, the operation of the node is checked. If you have problems with throwing on large sprockets, you need to turn the handle counterclockwise, pulling the cable.
- Then the chain is transferred to the smallest sprocket using a shifter.
- The L screw adjusts the position so that the largest sprocket is in the same plane as the controller foot.
Handlebar-mounted bike gearshift: installation and setup
The handlebar gearshift switch is used in urban, mountain and sports modifications. Comfort and safety of movement depends on the quality work of this unit. Before using the vehicle, check the operation of this unit. The speed setting is done by tightening or loosening the control cable.
Principle of operation
Before you know how to adjust the derailleur on a bicycle, you need to understand how it works. The functioning of the unit under consideration consists in pulling the cable of the front controller, which makes it possible to transfer the frame to the stars of a larger diameter. When the cable is loosened, the chain is thrown onto smaller sprockets.
The switching itself is carried out directly using the shifting type shifters located on the steering wheel. The rear is controlled by the right shifter, the front derailleur is controlled by the left analog. As a result, the chain is thrown among the front or rear sprockets.
External analog and combined system
Most multi-speed bicycles are equipped with this mechanism. It is used on both mountain and walking versions. The switch device consists of a controller and sprockets of different diameters. The whole unit forms a cassette system, the position of the speeds in which is changed with the help of the rear and front adjusters.
In such a device, from three to 24 speeds can participate. The adjustment of such a device can be done independently, having previously studied the principle of operation and the device of the mechanism.
The combo circuit is a mix of external and internal mechanisms. It is fixed on the rear hub. This type is not very popular, since it combines all the disadvantages of the modifications discussed above. The node is configured only by a specialist.