The device and principle of operation of the rear derailleur
Rear derailleur. a gearshift system 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 switch will be maximized.
Rear derailleur cock
The rooster (or cockerel) is the part with which the switch is attached to the frame. In addition, it provides more reliable protection of the frame from all-round impacts, such as a fall from a great height or a large overload of the bicycle. First of all, the rooster fails, and this saves the frame itself. After all, the rooster can always be changed, but the frame, if damaged, may not be repairable.
Therefore, this part is also very necessary, and if there is a need to purchase it, then choosing it, you should pay attention to the following characteristics: its alloy composition (what metals were used in the manufacture), quality (no chips and cracks) and of course the price.
It should not cost more than 500-600 rubles, of course it all depends on the wishes of the buyer. You can also purchase those that are much more expensive, but this is unnecessary.
Adjust the gearshift mechanism of the bike. Why gear shifts poorly on a bicycle
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.
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Setting the switches
Derailleurs on a bicycle are divided into front and rear. It is the rear ones that are most damaged when driving, so it is recommended to adjust them first. The process itself will be long, as there are more stars than in the front derailleur.
Important! It is necessary to proceed to setting the speeds on the bike only after all other parts have been checked for serviceability.
- Screw H must be tightened so that it aligns with the small sprocket.
- Screw L must be tightened so that it is on the line with a large sprocket.
- You need to set the highest speed on the shifter.
- The cable is stretched and fixed.
- If, after the performed manipulations, high gears are turned on with interference, then the cable must be loosened. If the situation is the opposite (the gears are badly thrown off), then the cable must be pulled.
The main configuration steps are now complete. The cyclist only needs to adjust the shifting accuracy. The procedure will get more complicated depending on the number of stars used. The chain is installed on the stars as follows: in front. on the smallest, on the back. on the largest. After that, the tension screw is tightened until the roller is as close as possible to the cassette. It should not rub against the cassette. A similar procedure is carried out with the chain, which is then installed on the largest chainring and the smallest rear chainring.
- Check the correctness and tightness of the fastening.
- Release tension at minimum speed.
- Screw L must be tightened so that a gap of 1 mm is created between the body and the chain.
- Fasten the cable with the bolt.
- Repeat the same procedure with screw H, but then the tension is set to maximum speed.
You will need to adjust the speeds until the chain begins to smoothly and freely change from one speed to another. If, when changing the speed, problems begin (difficult move, the chain flies, and so on), then the cable is tensioned using the adjusting bolt to the desired position.
After the manipulations with the settings are completed, the system is checked using a check-in, where the recommended gear ratios will be used. Adjustment is a standard procedure on any speed bike, as the tension in the cables will loosen over time. Therefore, setting speeds is often a planned activity that does not require replacement of parts.
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Chains and sprockets
These two parts are the main parts of the bicycle, since they directly move with the help of them. Most often, the stars are a cassette. which consists of 6-7 stars. It all depends on the number of speeds on the bike.
And the chains vary in pitch and length. The chain pitch is the size of one link on the sprocket or chain, and in accordance with the pitch on the sprocket, you need to select the chain with the desired pitch. The length is basically the same everywhere, but it can also be of an individual size. Then you will have to look for it for a very long time, or rivet it yourself.
How to adjust the rear derailleur on a bike
To independently configure all the mechanisms and put them into action, you need to do the following:
- you need to check if the switch itself is bent. This can be determined by looking at the tensioner. it should be parallel to the stars on the rear wheel. If it’s all about him, then you need to try to straighten it with pliers or other tools.
- if everything is fine with the switch, then most likely the cock is to blame (this is the mount on which the switch is placed). Most often, it also bends, and it has to be straightened periodically, so that at the first breakdown it needs to be replaced.
If all of the above is done or in order, then you can proceed directly to the switch setting itself.
This should be done as follows:
- put the switch on the highest speed (that is, on the smallest star)
- we find two screws. H and L. Turn the screw H so that the roller on the switch moves one mark with a smaller star
- put on the lowest speed (large sprocket), and rotate screw L until the roller is aligned with the large sprocket
- again set to the highest speed, and pull the cable. In this case, you need to make sure that he got into the special prem. It should be pulled tighter!
- check switching! If it switches very tightly, or does not switch at all, then you need to loosen the cable a little, or, on the contrary, pull it.
- if everything works well, then we can assume that the job is done.
It sometimes happens that a seemingly perfectly tuned rear derailleur doesn’t work well despite fresh cables and shirts. The reason may be that during transportation, the bicycle is clamped somewhere, and the cock bent slightly. If you cannot achieve a clear gear change, then remove the cock and put it on the table.
If it is slightly crooked, then you need to bend it. Do not overdo it, aluminum can give microcracks. How exactly to bend it. I will not advise. I do it in a handicraft way. I put it on the bike and pull it with my hands. Ideally, you need to edit with a special typewriter, which even takes into account the asymmetry of the dropouts.
What does it all depend on and what to do
Starter bikes are equipped with the cheapest transmissions, and the gears on them are poorly shifted and jammed. An experienced cyclist will quickly be able to determine the level of the drivetrain. The point is that its disordered work is not always associated with the class, but more depends on the setting and state. Let’s try to list most of the factors causing such problems.
It must be understood that the speed changes only when the chain moves forward. If you jerked the shifter, then you need to rotate the pedal so that the chain spreads from one star to another. If, when switching, clicking or any other extraneous sounds are emitted, you need to adjust the switching.
The main reasons for inaccurate switching:
- The transfer cable is torn, stretched, or is on the verge of breaking.
- The switch itself is broken or the spring in it is worn out.
- The teeth of the rollers are worn down.
- Switch needs to be adjusted.
- The chain or cassette is worn out.
- A lot of dirt got into the chain.
How to Adjust a Rear Derailleur – Limit Screws & Indexing
Cycling does not switch gears
Transmission components should be kept in good condition at all times, lubricating the chain promptly, adjusting switches and troubleshooting. As the kilometers increase on the bike, individual parts wear out, and if maintenance is not performed on time, the part may become unusable altogether. In this article, we will look at the most common problem associated with speed derailleurs.
Cables and shirts
This problem most often occurs among novice cyclists. It is enough to click the shifter or even remove the cable from the shirt and inspect it for contamination. In addition, the cable can be unwound somewhere, which will significantly affect the shifting.
Rear derailleur play
Move the rear derailleur towards you and away from you, keeping where the cable goes. Ideally, there should be no backlash at all, but a small free play does not represent anything criminal, especially on the initial transmission groups.
During operation, this backlash tends to increase, and then delays in switching, fuzziness, etc. begin. If everything is in order with the cables and the rooster, then with fine tuning you can overcome the negative effect of backlash.
To prevent damage, you need to be able to switch gears correctly.
Deformed rear derailleur bracket
There are times when a seemingly perfectly tuned rear derailleur malfunctions despite new cables and shirts. The reason may be that the bike was caught somewhere during transport, and the bracket bent a little. If it is not possible to establish a clear gear shifting, then it is worth removing the cock and putting it on the table. Crooked? You need to fix it. But it’s important not to overdo it, as aluminum cracks.
How to switch gears correctly?
Correct gear shifting allows you to ride easier and more comfortable with less effort, as well as increase the service life of all elements of the bicycle transmission. We have prepared several rules and recommendations on how to properly switch speeds on a bike:
- You can switch speeds only on the move, that is, while pedaling.
- For correct and smooth shifting when shifting gears, it is necessary to reduce the load on the pedals.
- Switching speeds should occur sequentially, you do not need to jump over several speeds at once.
- When going uphill, you should not throw the chain between the chainrings, but between the rear stars it is quite acceptable. If there is a slide in front, it is better to change the speed before you enter it.
- If, after switching the gears, extraneous sounds are heard, it means that the switching did not occur and it is necessary to squeeze the shifting lever.
If the fault diagnosis and adjustment is carried out correctly, in accordance with the algorithm, it lasts for a long time. Often, in practice, it is limited to setting the rear derailleur. Timely elimination of violations in the system will allow the transmission to serve for a long time without failures. To reduce the wear rate, it is necessary to use the speed system correctly.
Correct cycling gearshift setting
Modern bicycles equipped with a gear system allow you to move quickly and with minimal energy losses in any conditions: long climbs, rough terrain, roads with sharp turns that require constant changes in speed and gear ratio. This can also include driving against the wind, off-road, poor quality asphalt In general, the value of the transmission unit is simply colossal, especially on mountain bikes.
Despite the invaluable help, the transmission is great and requires frequent attention, care, and sometimes long and tedious fuss. One of the components that needs to be spent periodically is the shifting mechanism, which consists of front and rear derailleurs. At first glance, the arrangement of these parts seems complicated. In practice, setting up gear shifting is very simple.
Why bike speeds don’t shift well
Usually, the thought of needing to fix derailleur problems comes when the chain is shifting too hard between the sprockets, or the gears are not shifting at all. The problem comes suddenly, as an option, you can contact the master.
However, this issue can be resolved in the service in a couple of minutes, and the money will have to be paid in an hour. Maybe you should tinker yourself?
Before proceeding with the instructions for setting up the bike speed system, let’s determine why it does not work correctly:
- Switches are damaged. A complete replacement is needed to solve the problem.
- Deformed cock. protection of the rear derailleur. Usually it is advised to change, but once you can straighten.
- Spring worn or stretched cable. Replacement required, switch setting.
Very often, all the components of the transmission are in good condition, and the gears are still poorly shifted. New parts, or small workpieces installed in a transmission unit are a common cause of poor chain sprocket running.
Setting switches at home
Now let’s figure out how to set up the speed system ourselves. Derailleurs on bicycles with multi-gear transmission are divided into front and rear. The latter are most vulnerable when riding in a variety of road conditions, the risk of damage is higher compared to the front ones, but the adjustment must be done at the very beginning. Obviously, the rear derailleur serves more stars, so it takes longer to set up.
Attention! If there is damage, and the tensioner is not parallel to the frame and cassette, then it will not be possible to correctly adjust the system!
First you need screws L and H. they are clearly visible, no need to look. Also includes a cable adjuster, tension and fixing screws.
- H is used to align the roller with the small rear sprocket. By tightening the screw L, we set the roller on one straight line with the large rear sprocket.
- Set the highest speed on the shifter.
- Tension and fix the cable with the fixing bolt.
- Large gears should be included without interference, otherwise, using the adjuster, the cable is slightly weakened. Additional tension will be needed if gears are poorly reset.
Actually, the adjustment itself is made, it remains to adjust the switching accuracy. This is especially true for systems with a large number of stars. To do this, the chain is installed on a large chainring at the back and a small one at the front. By tightening the tension screw, we achieve the optimal position of the roller. as close as possible to the cassette. The same must be done and vice versa: set the chain to the maximum sprocket in the front and the minimum sprocket at the back. The roller should not rub against the cassette, just be located next to it.
How to properly set up the switch in front:
- Check device attachment.
- At minimum speed, release the cable tension.
- Use screw L to create a gap between the derailleur body and the chain (1 mm).
- Secure the cable with the adjusting bolt.
The same should be done with the H-screw. The maximum speed must be set, and the gap with the chain must not exceed one millimeter.
Adjust the speeds on both derailleurs until the chain is free to swing from one chainring to the other. If it is difficult to walk, it is necessary to adjust the correct position of the cable using the adjusting bolt.
After all the manipulations, the entire system is checked. To do this, you need to ride a bike and try all the recommended gear ratios. Note that on mountain bikes, the transmission adjustment is a common periodic procedure, and if suddenly the transmission goes tight, we are not in a hurry to draw conclusions about the breakdown, but we do what is described above.
Do not think that a high-quality transmission does not need to adjust the shifting system. Yes, it may be necessary to do this less often for shimano components, but sooner or later you will still have to face.
We just saw an easy way to adjust the front and rear derailleurs. Is it really necessary? Adjustment of the shift mechanism is necessary for the transmission, like tires for a wheel. Timely assistance to the traffic node will not only solve current problems, but also prevent them in the future. Eliminate all inconveniences in time and ride with pleasure!