How to assemble a rear derailleur on a bike

A bit of 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.

Rear Derailleur Replacement

  • 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.

assemble, rear, derailleur, bike

How to install a rear derailleur on a bike?

Having clocked many kilometers on a bike, 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 to put something more serious on an inexpensive bike used only for riding exclusively on asphalt. meaningless. Switching range was important, however, as the city is teeming with hills, hills and mountains.

So, replacing the rear derailleur begins with removing the old noname from the frame. it’s time for Shimano. The chain link 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. 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 sprocket should be on 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 next step is to insure against the possibility of the chain hitting the spokes, which is likely if the derailleur goes behind the largest sprocket. To do this, you need to move the switch to the largest star, carefully and without unnecessary effort. In no case by the roller, the mount of which is very easy to bend.

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.

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Queue for the cable. he should be free to wear 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.

I note that you will have to face such a concept as preventive repair 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.

Adjusting the bike’s rear derailleur yourself

Adjusting the rear derailleur on a bicycle is a process that many people find very difficult and only accessible to experienced mechanics. In fact, it turns out that not everything is so terribly complicated and everyone can deal with this procedure.

over, it is often necessary to adjust the correct operation of the rear gearshift mechanism on a bicycle. And it’s better to learn this yourself than to endure obnoxious cod and chain slip on the way to the workshop.

We have prepared instructions for you, which we use ourselves, we assure you that you will succeed! So let’s go:

  • Loosen the rear derailleur cable as much as possible, to do this, switch to the fastest gear (small sprocket at the back), and tighten all the screws that adjust the cable tension. If there is too much slack or looseness, unscrew the retaining screw on the rear derailleur and pull the cable a little.
  • Test the rear derailleur by lifting the wheel off the ground and gently pedaling back and forth. If the chain in this position of the rear derailleur strives to jump down from the smallest sprocket, adjust the lower position of the derailleur with the screw marked H. screw it in slowly. If, on the contrary, with a loosened cable, the chain tries to jump higher to a large sprocket, then unscrew the adjusting screw H.
  • Make one click of the shifter to change to a lighter gear. If the rear derailleur does not move the chain to the next sprocket, turn the adjusting screw on the derailleur counterclockwise, this will cause the derailleur to move the chain to the left, thereby throwing it one star higher. Important! In each gear, the upper roller of the rear derailleur must be in the same plane with the sprocket corresponding to the set speed on the shifter.
  • If the chain went over to the desired sprocket and strive to jump further, or immediately jumped over one star, turn the adjusting screw clockwise. This will loosen the cable slightly and cause the rear derailleur to move to the right, thereby shifting the chain into the correct gear.
  • Set the lightest gear on the shifter, which corresponds to the largest sprocket in the back. If the rear derailleur tries to reset the chain towards the spokes, limit its movement by tightening the screw L. But if, on the contrary, something prevents you from changing the speed to the lightest (there is no click on the shifter or it happens but the chain cannot jump to the last star), on the contrary. remove screw L.
  • Pedaling forward quickly, test the rear derailleur in each gear towards set and reset. If problems arise when changing speeds up or down, repeat steps 3 and 4.
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    But, as they say, it’s better to see once:

    When adjusting the rear derailleur on your bike, consider

    • the chain must be cleaned and lubricated, in which case it becomes much more elastic and easily moves with the switch in the right direction;
    • shirts leading the cable from the shifter (monoblock) to the rear derailleur should not have too much bends or come in at a very sharp angle. Thus, the movement of the cable inside the shirts will be difficult, and you can spend a lot of time adjusting the rear derailleur without achieving a result;
    • the rear derailleur frame must be strictly parallel to the stars (wheel). If there was a fall to the right side, or if you simply caught something with the rear derailleur, it could bend the earring that secures the derailleur and knock off its setting;
    • check for foreign matter between the stars at the back. It often happens that grass, weed, dirt, and sometimes even wire are stuffed into the cassette (ratchet) and this prevents the chain from taking its correct position;
    • check if the bike chain is stretched? It often happens that the owner missed the moment when it was necessary to change the chain, in this case, interruptions in the operation of the rear derailleur are possible;

    Materials (edit)

    The material from which the rear toggle switch is made of speeds is great for its strength, durability and price. Based on production materials, tumblers can be divided into the following categories:

      Steel is used for the smallest level rear toggle switches. These tumblers are usually the cheapest and most short-lived. Duralumin alloys are used in the mid-level rear toggle switches. Some parts of such toggle switches can be made of steel (adjusting bolts, a returnable spring, one of the frame cheeks). The strongest and most expensive toggle switches have a titanium spring and a carbon fiber frame.

    Replacing the derailleur on a bicycle: a sequence of actions

  • Then we install the chain on the smallest star so that the roller and the star are visually located on the same mowing line.
  • Carefully slide the derailleur back to the largest sprocket without grasping the roller, which is easy to bend. 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.
  • How To Disassemble/Assemble A Rear Derailleur

    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.
    Checking 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 and 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.

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    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.

    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 than trying to adjust and repair the rear derailleur on a bicycle that is already hopelessly damaged.

    For a bike that is used periodically and only on flat roads, it is not advisable to install an expensive derailleur of famous brands (Shimano, Sram, etc.). However, if you are planning to ride hills and slides, pay attention to mechanisms with a large range of speeds.

    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 have composite, carbon and titanium.

    how to put a rear derailleur on a bike

    The rear toggle switch is a parallelogram mechanism with a strong spring that moves a frame (tab) with fixed rollers along the axis of the cassette.

    The speed toggle switch is mounted on the cock with a hollow bolt and can swing up and down to maintain a constant distance from the idler roller to the cassette stars.

    Gear shifting in one direction is carried out by means of tension of cable, hydraulic or electronic drives. In the reverse side, the toggle switch moves under the tension of the chain passed through it.

    How To Replace Your Rear Derailleur | GCN Tech Monday Maintenance

    Switching speeds can only be when pedaling forward. When changing speeds, try to reduce the load on the pedals, although shifting may not be necessary even with a heavy load, because it can lead to accelerated wear or damage to the parts of the toggle switch.


    The rear toggle switches have two plastic rollers: a guide (upper) and a tensioner (lower). On some models of rear toggle switches, these rollers are not interchangeable with each other.

    There is also a difference between the rollers of different manufacturers and different models of toggle switches from the 1st manufacturer. The rollers are installed on plain or rolling bearings and are consumables. They wear out faster than the toggle switch itself, the bearings are loosened and the teeth are ground.

    In this case, they should be changed to new ones, otherwise the clarity of the gear shift will disappear.

    Preparing to adjust the rear derailleur

    It is required to clean the cassette from dirt, the rear derailleur itself, check the cable shirts, and it is also advisable to lubricate them if necessary.