How to replace a rear derailleur on a bicycle

replace, rear, derailleur, bicycle

How to adjust the bike’s rear derailleur

It must be said right off the bat that the hardest thing to tune is old, worn out switches. The cheapest spreaders made of low quality material wear out very quickly. After years of operation, so much material is produced in the joints of their mechanisms that backlashes are already becoming noticeable. Large wobbles of the rear derailleur will prevent you from adjusting to at least remove loud crackling when driving.

Adjusting the gearshift paddles is not a difficult job to be contacted by a mechanic. You will not be able to break the gearshift mechanism, the index system for changing speeds is the simplest and most reliable of all.

Sprockets and chains

Often the cause of poor bike rear derailleur performance is heavy chain wear. And most often, driving in vehicles in the mode of unauthorized combination of speeds, or with a skewed chain leads to this position.

There are times when a completely new chain mechanism is no longer suitable for use. the rear sprocket cassette is screwed with a bias onto the rear wheel hub. It will be fair to say that this happens when low quality, cheap parts are installed on a two-wheeled vehicle.

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 arise, 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.

Correct installation of the front derailleur

You can only start the front derailleur setting after adjusting the rear derailleur. Installation is the initial step in adjusting the speed switch. It’s very important to do it right.

  • 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 steering angle 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 upper mowing 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.
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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 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 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 a bike like this, there is less hassle, but it also has fewer options. In the transmission unit of such bicycles there are only two stars: one large and one small. Multi-speed bikes, 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.
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Chains and sprockets

Sometimes the cause of a problematic gear change is already the extreme wear of the chain drive. Long driving at prohibited speed combinations leads to increased lateral wear of the chain and sprockets. Do not ride in positions where the chain is very skewed: on the smallest sprocket in the front and rear and on the largest front and rear sprocket.

There are times when the new rear sprocket cassette is skewed onto the rear wheel hub, as many people buy the cheapest bike parts. And often, in order to eliminate the wobbling of the sprocket cassette, it is enough to adjust it by removing one or two adjusting rings inside the ratchet mechanism.

How To Replace Your Rear Derailleur | GCN Tech Monday Maintenance

Setting the travel limit to the smallest sprocket

To do this, sit down at the back of the bike and turn the adjusting screw marked “H”, at the same time the spreader is installed so that both the rollers and the smallest sprocket in the wheel are on the same mowing line.

Note: there is one trick in the implementation of this process. if the bike has been used for a long enough time and the spreader is not new, then you can adjust it qualitatively by setting the frame not in a straight line of the mowing line, but by shifting it to the right of the wheel literally by 1-2 mm.

You can check the correct setting of the travel limit on the smallest sprocket by rotating the wheel: the chain will not jump to the side, and the whole mechanism will work almost silently.

Setting the travel limit to the largest sprocket

Everything is done strictly according to the instructions:

How To Replace/Upgrade Rear Derailleur On A Bike

  • So that nothing interferes with the movement of the spreader, loosen the adjusting screw marked “L”.
  • Slowly crank the pedals and at the same time transfer the chain to the largest sprocket in the back.
  • We turn the adjusting screw marked “L”, thereby achieving alignment of the spreader in the position when its rollers and the largest sprocket of the cassette are on the same mowing line.

Note: in this case, if the spreader is already heavily worn, to facilitate the installation / adjustment process, you need to move its frame towards the wheel. In many cases, it is this minimum frame displacement that is not enough to throw the chain into the desired position.

Steering wheel switches

If the shifter breaks on the handlebars, the cyclist will feel it right away. the cable tension instantly weakens, so it’s easy to “diagnose” the problem. In this case, the shifter must be replaced, but experienced cyclists do not recommend purchasing expensive components. with the correct operation of such parts, even not the highest quality will manifest itself only on the positive side.

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How to fine tune the rear derailleur

From time to time, bike owners have to fine tune the rear derailleur. As a rule, such work is carried out in the following cases:

  • repair, adjustment or complete replacement of chain drive elements was carried out;
  • new cables and their shirts were installed on the two-wheeled vehicle;
  • poor quality cables were installed on the bike and they constantly stretch during operation.

In this case, the switch is adjusted by unscrewing the hollow cable tension screw. it is enough to make a half-turn to the left. After setting, be sure to check the operation of the mechanism. ride a bike in different speed modes.

Using the tips and tricks given in the presented material, you can carry out the whole process yourself. The only thing to remember is that the rear derailleur, which is badly worn out, must be replaced: no adjustments / adjustments / replacement of the cables will help.


The tools you may need are a Phillips screwdriver and possibly a 10 or 8 hex key or wrench depending on the switch. It is also very convenient to carry out work on a special bike rack, but you can also cope without it.

Derailleur repair for beginners

How to adjust the rear derailleur of a Shimano speed bike: detailed instructions

There is a popular belief among newbies that it is better not to go into the gearshift mechanism. The argument is. I don’t know how, I’ll knock everything down. However, there is nothing to be afraid of. self-adjusting the brakes on a mountain bike is no more difficult than adjusting the transmission. In addition, the indexing gearshift system is configured in such a way that it cannot be broken. The process should start with preparatory activities.

Additional accessories

replace, rear, derailleur, bicycle

Usually, setting up a Shimano rear derailleur for normal operation is limited to a quick readjustment. To complete it, you need to hang out the rear wheel, which will require one of the following:

  • Repair rack.
  • Rear wheel stand.
  • Ironing board.
  • Friend’s help.

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.
replace, rear, derailleur, bicycle

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 one, on the contrary, is the smallest.