Several things are configured in these devices:
- The tension of the cable and its movement. with the help of shifters and a special tightening screw.
- The extreme positions of the frame with the designations High and Low. to limit movement.
- Stroke and proportionality of the shift with the adjusting screw.
There are certain rules for measuring and positioning the frame, chain and sprockets, but it is better to read more about them in our material on setting up bicycle derailleurs.
Repair and installation
The switch may need to be repaired in several cases:
- Rooster repair. if the damage was on it, and not on the switch itself. we dismantle and fix it.
- If the rollers are loose or damaged.
- When the frame was bent.
Everything is corrected either by replacing the element (roller), or by straightening the bent parts, and sometimes by simply replacing the product. The most important thing is to correctly install the rear derailleur, our separate article is about this procedure.
Switches are rarely divided according to the cable entry point, but it should be understood how the shirt will fit in the event of a device change.
The standard approach is from the back, when the cable in the shirt makes a circle around the dropout, forming a small loop. In such a design, it is convenient to work with the cable, but the extra length of the cable and its bend lead to the need for more frequent maintenance and reduce the reliability.
An alternative is a straight line, where the cable enters the derailleur along the shortest path. Slightly more complicated cable and jacket operations are compensated by the greater reliability and security of the entire device. Originally only SRAM used this line, but in recent years Shimano and replica makers are increasingly switching to direct line.
The length of the frame affects the capacity of the rear derailleur. This is the sum of the two differences. between the largest and smallest stars of the cassette and the system, i.e. the minimum required capacity for a combination of stars is calculated by the formula:
If the capacitance of the switch is less than the resulting value, the chain will sag at certain speed combinations. If you take the switch capacity with a serious excess, this will not affect the operation of the switching system, but the risk of damage will increase, since the frame will be longer, and the switch itself is larger and heavier.
The price, of course, directly depends on the length of the frame, which, in turn, with some exceptions, correlates with the “level” of the model.
The switch looks and works mysteriously, especially for a novice cyclist. But first, let’s look at what parts the switch is made of and where it came from. By the way, the current “variant” of the rear derailleur is quite old. It was invented by the Italian Tullio Campagnolo back in 1950.
For a long time remaining an attribute of expensive sports and road models, it was only in the 80s that this switch began to appear on city bicycles, and in the mid-1990s it became the de facto standard for most designs.
Reaction to the rope
Many people have heard that derailleurs for bikes Shimano and SRAM. the leaders in the production of these devices. are not compatible. The reason for this is simple. different gear ratios are used in their products. If SRAM has 1: 1, i.e. when pulling the cable by 5 millimeters, the frame also shifts by 5 millimeters, while for Shimano it is 2: 1, i.e. when shifted by 5 millimeters of the cable, the frame will move by 10 millimeters.
So far, there is no sustainable proof of the advantages of a particular system, but the versatility and interchangeability continues to suffer, including due to the emergence of new transmissions for 10-speed cassettes that do not work with the shifters of even their titular manufacturer.
The de facto standard for mounting rear derailleurs is the cock. The cock is a small bracket that is designed to protect the rear derailleur and reduce the force of impact to the derailleur and frame. In fact, a small fuse, because you can often hear that it is not the frame that is bent and needs to be replaced, but the bicycle cock.
Rooster frames usually have a special “eyelet”, most frames come with a ready-made rooster. In some cases, it is not removable, i.e. repairs will require welding, but on most models it can be easily dismantled and replaced. Professionals recommend keeping a close eye on the bike cock, as its deformation completely changes the mechanics of the drive system, and always for the worse, leading to wear and damage to components.
In addition to the standard, a feather mount is used. a frame element used in professional downhill bikes and various sports models to increase reliability on difficult tracks.
A few years ago, Shimano patented Shadow technology for a more compact derailleur mount, but structurally remains one of the non-standard cock mounts.
The rollers in the gear selector are different, and when repairing or cleaning, it is very important not to confuse them, since the life of the chain depends on this, and the switch itself.
The guide roller, aka G-pulley, or guid pulley, is upper. performs several tasks at once:
- Directs the chain to the stars.
- Compensates for backlash due to small horizontal displacements.
- Increases feed smoothness and reduces noise due to small grooves on the teeth.
T-pulley, also known as tension pulley, is a tension pulley that prevents the chain from sagging.
The device and principle of operation of the rear derailleur
The rear derailleur is a gear shifting mechanism that allows the chain passed through its frame and rollers to move along the stars of the rear cassette or ratchet. The chain is thrown by moving the switch along the axis of the cassette (ratchet), and the switch can also be moved in the vertical plane to maintain a constant distance from the rear sprockets to the roller.
A cable drive is most often used as a switch drive, less often a hydraulic or electric drive. Moving from small stars to large ones is carried out by pulling the cable, and in the opposite direction by pulling the chain.
The speeds must be switched while pedaling, and with a light load. By adhering to this rule, the speeds will shift more clearly and the lifespan of the derailleur will be maximized.
Rear derailleur device
Rear Derailleur Design Types
Sooner or later, the rear derailleur wears out and it becomes necessary to replace it. Then the question arises about the interchangeability of the rear derailleurs. Switches can be categorized according to the following parameters:
- Switch frame length. this parameter is responsible for the so-called switch capacitance. That is, the length of the derailleur frame is responsible for the gear ratio range with which the rear derailleur can operate. Simply put, the capacitance of the derailleur is the sum between the difference between the small and large stars of the cassette and the system. For example, if the cassette is 11-32T, and the system is 22-44T, then the required capacity can be calculated using the following formula. (32-11) (44-22) = 43T. 43T is the minimum allowable capacity of the rear derailleur. The numbers indicate the number of teeth of the stars.
- Spring Direction. Indicates in which direction the switch is operated by the spring. The most popular direction is Top normal, that is, shifting due to the cable is carried out from a smaller sprocket to a larger one. All rear derailleur manufacturers adhere to this principle. But there is also a reverse direction (Low normal), when the chain is dropped by a cable to small stars, and switching to large stars is carried out by means of a spring. Rear derailleurs with this direction are only found in the Shimano range. These switches do not have significant advantages, and therefore did not gain popularity.
- The drive ratio is the ratio of cable movement to derailleur movement. This ratio can be 2: 1 (Shimano) or 1: 1 (Sram). It is these indicators that do not allow the switches of these manufacturers to be interchangeable. It is worth noting that there is no difference in the clarity of gear shifting from this indicator, although Sram claims the opposite (in practice, there is no evidence).
Cable feed to derailleur
There are two ways to feed the cable. straight and traditional. The traditional approach is to bypass the dropout. With a direct feed, the cable is attached to the switch from above and is laid along the shortest path. Direct supply has its advantages. lower weight and no loop that can catch on an obstacle. A special adapter can be used to lead the cable directly to the derailleur with a traditional cable attachment. Avid Rollamajic.
Traditional cable feed
Direct cable routing
Cable feed through Awid Rollamajic adapter
The rear derailleur was invented by the Italian Tullio Campagnolo and was first used in 1950. Its main purpose is to switch the reverse speeds of the bike. Since the switching of speeds is carried out by transferring the chain from large stars to small ones and vice versa, the chain tension must also change. The rear derailleur is also responsible for the chain tension. The rear derailleur is controlled by a shifter on the handlebars of the bike via a cable.
Rear derailleur rollers
In order to tension and guide the chain, the derailleur has two rollers. a tensioner and a guide. The rollers are usually made of plastic and are consumables. Since they wear out quickly, they need to be replaced periodically. The more the roller is worn out, the less clear the gear change will be. The tension roller and the idler roller between are not interchangeable. In addition, videos from different manufacturers are also not compatible.
Rear derailleur rollers
Rear Derailleur Mounting
There are two types of rear derailleurs on a bike, in relation to their attachment to the frame:
- Under the hook. the switch is attached to the bicycle hub. Such a mount is more reliable, but has a strong drawback. with a strong impact and breakage of the switch, the bushing also breaks, which entails high costs.
- Under the bolt. such switches are attached either to a special hole in the frame, or to or through a “cock”. a special adapter. The advantage of the rooster is that with a strong blow, neither the axle nor the switch breaks, but only the cock. The price of a rooster is incomparably small compared to a derailleur and a bushing.
Bolt-on rear derailleur
Rear hook derailleur
Mount holder (Rooster) rear derailleur
The metal from which the switch is made affects not only the price, but also the weight of the structure, as well as the strength. The cheapest are the rear derailleurs made entirely of steel alloy. The disadvantages of such switches are low strength and susceptibility to metal deformation. Steel derailleurs are used on lower end bicycles. The most advanced switches are made from titanium and carbon fiber. The spring in these rear derailleurs is titanium and the frame is carbon. Something in between and the most popular is the aluminum alloy. Despite the fact that the switch is considered aluminum, some parts are still made of steel (Adjustment bolts, spring).
How to adjust the rear derailleur on a bike
How to properly adjust the rear derailleur
To independently adjust the rear derailleur on a bicycle, you just need to strictly follow the step-by-step instructions from experts in this process. So, follow all the steps:
- Move the chain to the small sprocket with the right shifter.
- Unscrew the fixing screw and release the cable.
- Find the screw marked “H”. Use a screwdriver to adjust this screw so that the smallest star lies in the same plane with the rollers, which are located in the foot (frame).
- Pull the cable by hand and fix it with the screw.
- Check the operation of the switch, and if it does not work correctly, the chain does not switch well to large stars, then you need to tighten the cable more (either with the help of a drum or with a switch).
- Move the chain to the largest sprocket available in the cassette.
- Find the screw marked “L” and adjust it so that the tab (frame) and the sprocket are in the same plane. in this case, the cross-over will not be able to get into the spokes of the front wheel.
Correct gear shifting is determined by one main rule, the observance of which is very important. when driving, you need to make sure that the chain does not twist. This can happen if the chain is engaged at opposite extreme positions of the chainrings and chainrings. With this arrangement of the chain, it clings to all possible and impossible obstacles, is exposed to uneven load and wears out much faster.
Here are some tips to help you switch gears correctly:
- Better not to switch gears when driving downhill. The first thing that will happen to you is the loss of your riding rhythm, which will affect your stamina and movement speed, respectively. This is also not worth doing, since when climbing uphill the chain tension is already quite high, and if at the same time throwing the chain between the stars. Such actions will have a detrimental effect on the resource of parts, and, soon, a breakdown may follow. So you need to switch gears before lifting, at the moment of the greatest relaxation of the chain.
- A huge number of cyclists rarely use the front derailleur on their bike. It is difficult to answer why it happened so, but, nevertheless, it is a fact. It is much more efficient to use forward gear when driving on a sloping road. One shift on the chainrings, in this case, will have more effect than two or three changes on the rear. Just put the chain in the back on the middle sprocket and shift with the front.
- When a fairly serious descent is planned on your way, then, again, switch gears before starting to go down. This is due to the fact that when the process of driving downward begins, it is better not to be distracted from the brakes, and you will need to follow the road especially carefully, because falling on the descent is an unpleasant thing.
- Gear shifting should be smooth. There should be no rumbling, rattling, knocking and other extraneous sounds. If you follow this, then the gearshift system will serve you for a much longer time.
However, the shifter is a kind of “heart” of the transmission system and, for the most part, it is he who is responsible for the quality of gear shifting. Today, a limited number of companies are involved in the production of high-quality derailleurs, and the most popular among them is the Japanese giant. Shimano.
To make it more convenient for customers, all Shimano derailleurs are divided into groups. Let’s dwell on each of them in order:
- Shimano Tourney is the easiest beginner derailleur. They are distinguished by their low cost and high reliability. Bicycles equipped with components of this class are designed to be used at a leisurely pace on the track or on tightly packed ground. This Shimano derailleur cell needs constant adjustment and starts to fail if too much dirt gets on it. Fits Shimano 2300 Road Group.
- Shimano Altus / Acera is also the entry-level equipment. But Acera derailleurs are already installed on bicycles designed for use in sand and mud, naturally only at the amateur level. For those people who, for whatever reason, cannot get more expensive options and ride both on the ground and on asphalt, this type of Shimano derailleur is ideal. Fits Shimano Sora Road Group.
- Shimano Alivio. This group of equipment is something in between, it cannot be called professional yet, but it is no longer amateur. Equipped with Alivio derailleurs, the bikes are great for recreational riders and cycling trips. This Shimano derailleur group is reliable and unpretentious. The price-performance ratio in this group of switches is implemented most successfully. Fits Shimano Tiagra Road Group.
- Shimano Deore is a professional line of derailleurs, but if you look at things soberly, the differences from the Alivio are not so great. All that changes is the indicators of lightness and reliability, they get a little better, but the price rises significantly. Fits Shimano 105 Road Group.
- Shimano Deore SLX and XT are lightweight and reliable professional equipment. The reliability of the Deore SLX / XT derailleurs is eloquently reflected in the cost: the price of a Shimano Alivio rear derailleur is about 45. and the Deore costs between 90 and 110. Ideal for professional athletes to train every day. Fits Road Groups. Shimano Ultegra and Ultegra Di2.
- The Shimano Deore XTR is the ultimate racing equipment. Not afraid of any stress. Extremely expensive. Fits Shimano Dura-Ace Road Group.
Shimano doesn’t just make derailleurs for mountain and road bikes. There are many derailleurs available for touring, city and adventure bikes. But we do not consider them, since these bicycles are not popular in the CIS.
ADJUSTMENT AND ADJUSTMENT
Sooner or later, any bike enthusiast begins to notice that the gearshift system emits extraneous sounds, such as crunching, rumbling, and so on. It happens that during a gear change, the chain jumps a couple of sprockets or the opposite situation: you cannot switch to the required sprocket. So what’s the deal? You just do not have gear shifting configured. So how do you set your bike speeds? Let’s try to figure it out.
The gearshift setting can get lost due to the fact that you are not familiar with the gearshift rules and are switching them incorrectly. Or your gearshift system is simply too dirty and needs to be flushed out. But the reasons are a separate conversation, and we will focus on setting.
We will not go into the nuances of professional tuning. professional cyclists are unlikely to search for speed settings on the network. Therefore, let’s move on to a short course on speed tuning:
- Fix your bike upside down (using a special stand or simply placing it on the handlebars and seat). The speed setting is carried out using special bolts on the switch.
- Now you need to set the chain in the leftmost positions (on the large chainring and small rear). After that, unscrew the part that serves to fix the cable to completely unhook the cable.
- Now, tightening one of the bolts on the gear selector, you need to adjust the two gears so that they are opposite one another. You will know which bolt to turn by the “H” or “High” mark next to it. What does high speed mean?
- After that, we install the chain in the rightmost positions of both stars (on the largest rear and smallest in front). Adjust the gears again with the second screw, which is marked “L” or “Low”. Putting the stars in one line.
- Now, you need to install the chain on the middle sprockets at the front and rear and adjust the gear shifting as precisely as possible using a screw called a “thumb” and located directly on top of the cable. It must be remembered that our goal is to ensure that the middle gears are opposite one another. Before you start twisting the “lamb”, it is better to perform a test drive, which will give an idea of how difficult it is to switch or, conversely, too easy.
Putting the asterisks one opposite the other, do not worry if there are slight inaccuracies, plus or minus a couple of millimeters does not affect anything: the system does not provide such accuracy. But still, the gear changes will be slightly better if the stars are aligned. For this reason, after the test drive, it will become extremely clear where exactly you need to do more detailed settings.
ADJUSTING THE FRONT SPEEDS OF THE BIKE
You need to adjust the forward speeds in about the same way, there is nothing difficult there, and you can figure it out at the level of intuition, therefore, we will consider only some points. The chain runs along the chainrings with a metal stop that can be adjusted with two bolts. The principle is the same, so, as mentioned earlier, there is nothing complicated about it. And, again, in order not to suffer again with the setting, switch the speeds correctly, as described above.
How to put a rear derailleur on a bike
Having traveled many roads on a bicycle, you are convinced that for a comfortable ride, buying stylish grips and choosing the right tires is not enough, much more important is the presence of a branded rear derailleur, which will be correctly installed and configured.
The gearshift mechanism was invented by Tullio Campagnolo in 1950. This discovery made a splash among bike manufacturers, who from that moment on, polls began to equip new models with this device.
The main purpose of the mechanism is to increase or decrease speeds by throwing the chain over the stars in the cassette. In addition, the rear derailleur on the bike prevents the chain from sagging by keeping it taut. than half a century has passed since the invention of the device, during which time many of its varieties have been created.
The number of gears that you can choose depends on the length of the frame: the longer it is, the more speeds are provided by the design of the bike. However, it is impossible to say unequivocally that a long frame is better, someone likes a short frame that is not afraid of stones. And here everyone is right in their own way!
How to Install a Rear Derailleur
What is the rear derailleur made of?
The material of manufacture can be different: from stainless steel to titanium. On budget bicycles, as a rule, steel and plastic switches are installed. such products are short-lived, work poorly. Models of the middle price segment are equipped with an aluminum movement, and the most expensive ones are composed of composite, carbon and titanium.
Installing the rear derailleur on a bicycle
Owners of an old bike, equipped with a switch of an unknown brand, always reach out to “bring it to mind.” Often, with a device assembled independently from spare parts of various brands, many problems arise: from the constant throwing of the chain over the star to the complete “sabotage” of the movement. Therefore, it is easier and cheaper to “get hold of” a new one, rather than trying to adjust and repair the rear derailleur on a bicycle, which is already hopelessly damaged.
For a bike that is used periodically and only on flat roads, it is impractical to install an expensive derailleur of famous brands (Shimano, Sram, etc.). However, if you are planning to ride on hills and slides, pay attention to mechanisms with a large range of speeds.
Replacing the derailleur on a bicycle: the algorithm
- The replacement process begins with removing the old mechanism from the frame. To do this, open the chain link, unscrew and remove the old switch.
- Next, to the “cock”, which is a protruding triangle with a hole, we fix a new mechanism. It should be screwed on well, but not too tight.
- Then we install the chain on the smallest star so that the roller and the star are visually located on the same line.
- Carefully slide the derailleur back to the largest sprocket without grasping the easy-to-bend roller. Thus, you will be insured against the risk of the chain hitting the spokes.
- Using the adjusting screw, we fix the position of the switch so that it still remains opposite the large star. If the mechanism hits the star, you can lose the spokes, too much clamping is fraught with failure of the lower gear.
- Moving on to the cable. normally it should move freely in the shirt. It is necessary to check the absence of creases and the course itself. To do this, we install the chain on a small star, pull the cable and fix it in a taut position.
- We check the operation of the mechanism. First of all, turn the pedals. in the process there should be no clicks, and the very switching of speeds up / down should occur smoothly, without jumping over the stars and without delays. At first, it is better to take a screwdriver on a bike ride. under load, the mechanism may need to be adjusted.
Regardless of the mechanism of which company you choose, sooner or later you will have to face preventive maintenance. After all, the rollers are consumables and wear out as the bike is used, so from time to time it is necessary to carry out their preventive replacement.
Many people think the rear derailleur is much easier to set up than the front derailleur. In both cases, you will have to make some effort, but this work will pay off with interest in comfort while riding. If you do not want to waste time installing the derailleur, contact us for a bicycle repair service.
What to do if you can’t adjust the bike’s rear derailleur
There are several methods for solving this issue. But if the standard tuning instruction did not work, to tune the rear derailleur you need to:
- dismantle the chain, remove the cable;
- move the switch to the chain position to the smallest star;
- use adjusting bolts (this way you can tighten the cable);
- set the adjusting bolt H to the extreme position;
- move the part called the parallelogram to the big star and adjust the position of the bolt L.
The regulator is fixed with bolts. It must be set to the extreme position. After that, the chain must be displaced in this order: the front cassette is the largest star in diameter, the rear, on the contrary, is the smallest.
Bicycle front derailleur
The transition to the setting of this mechanism is possible only when the rear derailleur is set. This is important for Honor 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.
How the switches work
Using the handle and shifter, the cyclist activates the required speed. In a certain position of the handle, the cable is pulled. As a result of this tension, the frame is thrown onto larger sprockets; when the cable is loosened, it is not thrown onto small sprockets. As mentioned above, you can start setting up your bike from the rear derailleur. Procedure for adjusting the rear derailleur:
- select the second star in the front block, and the smallest in the rear one and set the switch chain on them;
- The bike’s rear derailleur system has two bolts that act as stops. One is abbreviated as H, and on the other. L. These two bolts are used to adjust the high and low gears on the sprockets. If during the adjustment process any extraneous sounds occur, you can get rid of them with the help of the latch;
- check the tension of the cable and if the tension does not correspond to the required one, use the regulator located on the shifter;
- Test the switching quality. If the switching occurs smoothly, no extraneous sounds are heard, then you did everything right.
How to properly adjust the rear and front derailleurs on a bicycle: photo and description of the process
Despite the fact that the bicycle was invented a long time ago and, it would seem, should have been out of date for a long time, but this two-wheeled vehicle is gaining more and more popularity every year. Cycling enthusiasts prefer this type of transport due to its convenience, ease of operation, environmental safety and practicality. Not only ordinary bicycles are very popular, but also mountain, track bikes, in which modern innovative technologies are involved. In order for the owners to enjoy cycling, they need to take care of it and monitor the condition of all parts and assemblies. If, in the process of cycling, you hear extraneous sounds, creaking, knocking and twitching during gear shifting, it’s time to pay attention to such a detail as the gear selector.
The gear selector is an important part of a multi-speed bike. Thanks to this component, it becomes possible to move in extreme conditions, which include movement against the wind, ascents, poor road quality. The transmission unit must cope with all these problems. The quality of the ride and the safety of the cyclist depend on the smooth operation of the speed switch. This skill is very useful, and every bike owner should learn how to independently adjust the gear shifter. Each cyclist can make adjustments to the bike’s gear shifters on their own. You need to study the theory in detail by reading the instructions, or using the advice of experienced bike owners.
Before setting the derailleur, the rear derailleur must be adjusted. Placing the bike in the correct position (wheels up) will greatly facilitate the entire adjustment process. So, all the necessary details will be in sight, and it will be much easier to get to them.
Reasons for poor gear shifting:
- physical defects of the switch parts;
- contamination of parts. To prevent this from happening, the components of the transmission unit must be periodically cleaned of dirt, dust and old grease;
- worn out cable with elements of damage. Such a part requires replacement;
- damage to the cock.
If you observe damage, deformation and wear of the constituent parts, they must be replaced as they are practically irreparable.
If all parts are OK, adjust the switch. What is the speed selector made of? The components of the speed switch are as follows:
- The handle for shifting the speeds, located on the steering wheel;
- A shifter that attaches to the handlebars near the handles. Handles and a cable are attached to the shifter. It is with the participation of the cable that the impulse is transmitted from the shifter to the stars;
- Cassette, which includes stars of different sizes;
- front fixing mount;
- rear derailleur, whose main function is to transfer the chain to the necessary sprockets.
Correct installation of the front derailleur
You can start the front derailleur setting only after adjusting the rear derailleur. Installation is the initial step in adjusting the speed switch. It’s very important to do it right.
How To Disassemble/Assemble A Rear Derailleur
- before installing the switch, it is necessary to inspect the condition of the constituent parts and, if necessary, clean them from dirt and lubricate.
- The next step is to adjust the location of the front derailleur. On the frame, it should be located along the pipe under the saddle.
- Set the angle of rotation parallel to the drive sprocket on the front cassette of the transmission unit.
- Next, you need to adjust the gap between the underside of the derailleur frame and the top line of the teeth of the large gear. The gap should be minimal.
- Adjust the cable tension.
- Place the chain close to the inside of the frame.
It is also worth paying attention to setting up the chain. The bicycle chain is a very important element, with the help of which the impulse is transmitted from one chain to another and the adjustment process takes place. The technical condition of the circuit is of great importance for the operation of the entire system. If, for some reason, the bicycle chain stretches or deforms, this cannot but adversely affect the operation of the entire transmission unit. To prevent this from happening, the chain must be periodically removed and cleaned, and then set to the correct position. There are lock and lockless models of bicycle chains. They differ in the way they are connected. To remove the locking chain, it is enough to find the link with the lock and disconnect it with a screwdriver. The lockless bicycle chain is disconnected using a squeeze. This tool helps to push the link axle out and make the connector. If it skews for some reason, this can adversely affect the gearshift process.
One of the best manufacturers of bicycle parts, including derailleurs, is the Japanese company Shimano, which has a proven track record of producing products in which Japanese quality is combined with budget and price. Shimano derailleurs (fig. 3) are suitable for all types of bicycles. Shimano derailleurs are installed on both regular touring bicycles and mountain and track bikes with gearboxes up to 33 speeds.
Another recognized market leader is Sram. The products of this company are used on bicycles of the city bike category, as well as on sports bicycles. Sram products are of good quality and affordable price for cycling enthusiasts.
Every bicycle owner who prefers this type of transport to others is obliged to understand how to switch its speeds. It is believed that the more speeds a bike has, the better it is. But in fact, speed only allows you to improve the quality of maneuvering and squeeze the maximum out of the bike’s capabilities, so then everything depends on the dynamic efforts of the person riding the bike. Conventional bicycles have a simpler design compared to high-speed ones. With such a bike there is less hassle, but it also has fewer possibilities. In the transmission unit of such bicycles there are only two stars: one large and one small. Multi-speed bicycles, which have gained popularity in recent years, have two sets of sprockets in their transmission units: front and rear. Each cassette consists of stars of different sizes. To switch gears correctly, you need to remember a few basic rules:
- If your bike is not equipped with a planetary hub, you only need to switch gears on it while driving, otherwise there is a danger of damage to the bike.
- During gear shifting, it is not necessary to apply significant dynamic forces, in order to eliminate the danger of a burst of flowers, it is advisable to change gears sequentially, without making sharp jerks.
External switching mechanisms
All bicycle derailleurs can be divided into two main types:
- internal gear shifting mechanisms;
- external gear shifting mechanisms;
- combined mechanisms.
How to assemble a rear derailleur on a bike
First of all, it will be useful to answer the question: “And why are there gear selection mechanisms on the bicycle at all?” The fact is that the correct choice of gear allows you to vary the cadence (cadence) and the effort on them for the most efficient distribution of energy. This happens by changing the gear ratio between the pedals and the wheel. For example, when driving up a steep hill, you need to select a gear lower: in this case, the effort required to press the pedal will decrease, although the number of revolutions of the pedals required to drive up the hill will increase. If, on the contrary, you are driving down a steep mountain, then you need to select the highest gear that will allow you to develop the maximum speed. It was in order to change gears on the go that various types of switches were invented.
Internal shift mechanisms (planetary hubs)
On a bicycle equipped with this type of derailleur, you will not see cassettes with sprockets of different sizes and with different numbers of teeth and hinged derailleurs. As a result, the wheel drive has only one sprocket in the front, a chain and one sprocket in the back. How then is gear selection ensured? The fact is that the entire mechanism in this case is inside the rear hub.
|Appearance of the planetary hub||The structure of the planetary hub|
Currently, a fairly large number of planetary bushings are produced with various numbers of gears (from 3 to 14). In addition, the vast majority of planetary hubs have a built-in brake. These gear shifting mechanisms are most widely used on road and walking bikes, although sometimes they can also be found on mountain bikes.
- resistance to adverse road and weather conditions, due to the fact that the switching mechanism is completely in the housing;
- built-in brake;
- high reliability and durability;
- the ability to shift gears without turning the pedals;
- ease of maintenance.
However, planetary hubs also have significant disadvantages:
- high weight;
- strong friction of nodes, which complicates movement;
- repairability in field conditions.
Its task is to transfer the chain from one chainring to another. The principle of operation of such a switch is very simple: a chain passes through a frame that moves thanks to a parallelogram mechanism. If it is necessary to switch, this frame moves and takes a position above the corresponding sprocket, as a result of which the chain also jumps to it.
|Shimano deore XT front derailleur|
The front derailleurs differ in several ways, as shown below.
- Method of attachment to the frame. Most often, fastening with clamps is used. over, the clamps themselves can be designed for different diameters of the seat tube, which should be taken into account when purchasing. However, there is a mounting method in which the plate holding the switch is clamped by a carriage or cartridge in order to be able to mount the switches on frames with non-standard geometries.
- Installation angle in relation to the frame. If this parameter is selected incorrectly, a situation may arise in which the derailleur frame touches the bike frame. In this case, correct gear shifting becomes impossible.
- Method of fastening the cable. The drive cable, depending on the method of attachment to the bike frame, can be brought to the switch from the bottom or from the top. There are universal models of switches that are designed for two connection methods, but there are also those that are designed for only one.
In general, all front derailleurs have one significant drawback: they are practically unable to transfer the chain from one chainring to another under load (especially from a smaller chainring to a large one). Manufacturers are trying to solve this problem, as a result of which various systems appear that use pedaling energy for shifting. However, they are expensive and not very efficient.
A little boring theory
The rear derailleur mechanism throws the chain over the cassette stars, allowing you to lower or increase gears (for reference, it was invented by the Italian Tullio Campagnolo back in 1950). This device also keeps the chain taut. Since the invention, many varieties have been created. A little about the main, most characteristic features.
- Manufacturing material. From steel to carbon. The entry-level models are equipped with steel, and not always of good quality, and plastic. In the right hands, these switches even work sometimes. Models of the middle category are in most cases made using aluminum. The most expensive models can boast not only precision in work, but also titanium, carbon or composite.
- Frame size. In theory, everything is simple. the longer the frame, the more gears you can select. However, one cannot say so categorically, since someone will prefer a short frame that is not afraid of stones, while others are interested in greater comfort in switching. And everyone is right in their own way.
You can still describe in detail the action of the spring or the options for the location of the cable for a long time. However, many good articles have been written on this topic. I will only note that there is not much difference from which side the cable enters the switch. So, now about the interesting.
How to install a rear derailleur on a bike?
Having clocked many kilometers on a bicycle, I was convinced that a branded derailleur is much more important for a comfortable ride than stylish grips or leather Brooks. But it’s not enough just to get Shimano or Sram, the quality of installation and setup is important.
Installation and adjustment
Reference: The Shimano Tourney TX is the entry-level model, although the exterior design suggests a higher class.
And putting something more serious on an inexpensive bike, used only for riding exclusively on asphalt, is pointless. Switching range was important, however, as the city is teeming with hills, hills and mountains.
So, replacing the rear derailleur starts with removing the old noname from the frame. it’s time for Shimano. The link of the chain is revealed. If this is not the case, then you need to use squeeze.
The old switch is unscrewed and removed, and a new one is hung in its place and screwed to the “cock”. a protruding triangle with a hole in the frame. It is worth tightening well, but without undue enthusiasm.
We put the bike chain on the smallest star. Visually, the roller and small star should be in the same line. The small star is the highest speed, therefore we adjust the position of the roller with the screw H.
Help: the letter H is an abbreviation for high gear, that is, top gear.
The adjusting screw fixes the position of the switch exactly so that it is opposite the large sprocket. Going behind it is fraught with the loss of knitting needles and good mood. If the switch is too tight, there will be no lower gear.
Queue for the cable. he should walk freely in a shirt. We check the progress and the absence of creases. On this switch model, you can see the place for the cable to pass. We put the chain on the smallest sprocket, tighten the cable to remove the slack, fix it. Thus, installing the rear derailleur and adjusting it are two integral, complementary processes.
Now check the operation of the entire mechanism. There should be no pronounced clicking sounds when pedaling from the rear derailleur side. Switching up / down must be accurate, without skipping and delays. And even if everything fell into place, it works accurately, quietly and without delay. for the first trip it is worth taking a screwdriver with you. Working with a load may well require minor adjustments.
Note that you will have to face such a concept as “preventive maintenance of the switch”, regardless of its price category. As the rollers, which are consumables, wear out, their timely replacement will be required.
It is believed that installing and adjusting the rear derailleur is much easier than the front derailleur. However, you will have to spend time and effort, but this work will pay off handsomely during the trip.
Preparing to adjust the rear derailleur
Proceeding to setting the rear derailleur, it is necessary to clean the main elements that are included in the gearshift system.
It is required to clean the cassette of dirt, the rear derailleur itself, check the cable shirts, and it is also advisable to lubricate them if necessary.
Speed Bike Rear Derailleur Setting. Self-Setting Bike Speeds
Nowadays, the market for bicycles is amazing with a variety of rear derailleurs for bicycles, they come from the entry level to the pros. But, despite this, the setting of the rear derailleur has approximately the same principle of adjustment. Nearly all modern rear derailleurs have 5 adjustments.
- cable fastener, screw or nut
- adjusting drum
- limiting screw L (low). for adjusting small gears (large sprockets)
- limiting screw H (high). for adjusting large gears (small sprockets)
- chain tensioner adjusting screw
On different models of rear derailleurs, the L and H adjustment stop screws may be on the side or back. It should also be remembered that you can also adjust the rear derailleur using the adjusting drum, which is located on almost all shifters. This is very convenient because cables tend to stretch.
Steps for adjusting the rear derailleur on a speed bike.
- Needs to switch to smallest sprockets in front and back.
- The tensioner drums (on the switch and on the shifter, if available) must be turned to the initial value, turned clockwise until they stop. This will make it possible for us in the future, when the rear derailleur cable is weakened, to tighten the cable using this drum.
- We unscrew the screw or nut, weaken the cable itself. In this case, you can pull out the cable and check for defects or contamination of the cable jacket.
- Adjustment of large gears with screw “H”. It is necessary to turn the adjusting screw “H” until the derailleur rollers and the small sprocket are on the same straight axis. If, when switching to large gears, there is a shift of the rollers relative to the stars to the right, then it is necessary to turn the screw “H” clockwise, tighten, until they become exactly on a straight axis. If the rollers are shifted to the left, it will be difficult for the chain to switch to lower gears, it is necessary to loosen the “H” screw. turn it counterclockwise. With the correct adjustment of large gears while rotating the wheel by turning the pedals, the chain should work silently without hooks on a small star.
Further, it transcends the adjustment of the chain tensioner, if any. To do this, place the chain on the smallest front sprocket and the rear on the largest. Then we pedal back, if the upper roller of the rear derailleur touches the teeth of the sprocket, then it is necessary to turn the adjusting screw to achieve such a value so that the roller is at a distance of about 5 mm from the teeth of the sprocket. Then we need to check the chain tension, only now we need to switch to the small rear sprocket.
If, after completing all the steps, you cannot clearly adjust the rear derailleur of the bike, then most likely the rear derailleur needs repair or replacement.
Perhaps the lever is bent due to falls or other circumstances, you can try to repair the rear derailleur by aligning the lever.
Not clear switching can also be due to a cassette not working properly, various deformations, distortions. Also, the reason for a fuzzy shift may be hidden in a dirty cable or a malfunction of the shift lever. After the correct setting of the rear derailleur, you can proceed to the speed bike front derailleur setting.