How To Rebuild A Rear Bicycle Derailleur. Breakdown / Clean / Service. Shimano Deore XT
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.
- 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.
To understand the process of self-adjusting the speed switch, you need to know the definition of some specific terms, otherwise it will be difficult to understand the instructions.
- Speed switch (crossover). This is a transmission element that is specifically responsible for gear shifting. If there is a rear crossover, then it also acts as a support for the tension of the bicycle chain. The crossover (back and front) can be described as follows: it is a parallelogram mechanism equipped with a powerful return spring, on which the frame is fixed. The rear derailleur has two rollers inside the frame. if the level of cable tension increases, then the frame shifts the chain to large stars, and if this cable tension decreases, then the chain is shifted towards small stars with the help of the frame. The mechanism of the front derailleur works in the same way.
- Shifter. It is designed to switch speeds by changing the tension level of the cable. Most often, the shifter is located on the handlebars, but in some models of bicycles it can also be located on the lower tube of the frame triangle. Note:shifters and speed switches have a common connection on the steering wheel (this is provided by a cable) and are covered with a jacket.
- Cassette. This is the name of the rear transmission unit, which consists of stars of different sizes (of different diameters and with a different number of teeth) and is installed on the rear hub drum. If the bike is old, then a ratchet is used instead of a drum in the rear hub.
- Cock. It is a metal part that helps maintain the integrity of the frame and rear derailleur in the event that the vehicle has been hit. The rooster is always attached to the frame, and a cross-over is already attached to this metal part. When a blow occurs, it is this very cock that breaks, and the frame and the speed switch (crossover) remain intact.
- System. This is the name of the front transmission unit, which consists of stars of different diameters and with a different number of teeth. These stars are fastened to each other and the connecting rods with special hollow bolts on the connecting rods, but you need to know that there are no hollow bolts in cheap bicycles. the stars and connecting rods are riveted to each other.
Front derailleur device
The design of such a system is quite simple. We list the main components and their functional features.
An element designed to attach the device to the frame of your bike.
An element in the construction of which there are hinges and a special spring. This element got its name because of the parallelogram shape. It represents the main moving part of the device, and also a frame is attached to it, about which a few words below.
A detail in which both the outside and the inside play an important role. A chain runs along the inside of this element.
And these elements are also called constraints. These are two bolts that are used to restrict the movement of the frame both towards the bike frame and in the opposite direction.
Another bolt that holds the shift cable.
Front derailleur circuit
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 one, on the contrary, is the smallest.
Testing the work done
When the installation of the front derailleur on your bike is complete, you can start testing. Select a straight section of road that is free of sharp descents and ascents, and test the device while driving. If you find any functional problems, you can make adjustments on the go at low speed. With a little skill, you will learn how to easily adjust the front derailleur on your bike.
How to properly shift gears on a bike. How to determine the number of gears on a bicycle, what is the principle of the transmission, basic rules and recommendations for shifting gears.
Correctly selected bindings for a snowboard is the factor that can ensure a comfortable ride on a ski equipment. Choosing the perfect mechanism.
Timely replacement of the gearshift cable on a bicycle is a guarantee of the normal functioning and integrity of the mechanism. Replacing the cable is a simple procedure, it is quite possible to do it yourself.
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.
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.
Sometimes it happens that pedals bounce forward when power pedaling. This occurs most often when the cyclist pedals while standing. In principle, this can be called another reason why it is worth switching to a low gear once again while remaining in the saddle, rather than jumping on the pedals while remaining in a high gear.
However, pedaling, chain slipping past the desired sprocket, or spontaneous gear changes are extremely rarely the result of a breakdown of the gearshift itself.
To diagnose and then solve the problem, you first need to understand exactly whether the chain slips past the star or the gears shift by themselves:
- Bouncing involves jumping over a chain to an adjacent star under load. After jumping, the chain usually returns to the original star. This phenomenon, as a rule, indicates that the chain or gears are badly worn out. Chain bounce is usually seen on smaller stars in the back, in conjunction with the use of a small guide star in the front. Chain slippage can also be caused by seized chain links.
- Spontaneous gear shifting feels similar to overshoot, except that the chain does not return to the original sprocket. This phenomenon may be due to the flexible frame and the increased coefficient of friction of the cable.
Replacing the rear derailleur cable
First, the cable is pulled from the shift lever through all existing jackets. It is also important to check the condition of the shirts and replace them if necessary. Then you should pull the cable and move the switch lever to the extreme position. This corresponds to the position of the chain on the smallest star.
Replacing the cable
To change the gearshift cable, first you need to loosen it as much as possible, that is, transfer the chain to the smallest leading and trailing stars. If the cable is torn, you need to twist the pedals for a while. the chain itself will take the desired position. In this case, to move the shift lever to the extreme position, you will need to pull the cable.
By loosening the cable anchor bolt and loosening the cable, you can easily remove the jacket. The pressed-on end of the cable should be visible in the hole in the shift lever (if you remember to move the cable to the extreme position).
Shift levers built into the handlebars. such as SRAM’s GripShift. are the most difficult to change the cable, and generally require disassembly.
After replacing the cable, it is usually not necessary to adjust the stop screws on the gear selector itself, but you will have to adjust the cable tension. To do this, screw the adjusting drum on the shift lever until it stops and unscrew it one turn back.
How switches work
Most modern bicycles have gear shifting systems (derailers). The switching principle is based on throwing the chain from one gear to another.
At first glance, the construction of the shifters may seem complicated, but in reality it is very simple, and is based largely on physical effort. This is especially true for the front derailleur.
The front derailleur consists of a steel frame that moves laterally. Previously, in old switches, a special piston mechanism moved the frame. Modern designs use a parallelogram to reduce friction.
The shifting process is based on lateral chain displacement. The frame pushes the chain sideways, causing it to move at an angle to the leading star. The moment the angle becomes excessively sharp, the chain can no longer hold onto the gear and bounces down onto an adjacent smaller sprocket.
When switching from a smaller star to a larger one is required, the process proceeds a little differently. The chain is pressed by the frame to the neighboring star and friction occurs. Then the chain is picked up by the tooth of the larger sprocket and finally passes to it.
Mountain Bike Derailleur Hanger Replacement
Modern drive sprockets are equipped with special pins, bevels and bumpers on the sides so that the chain pick-up is noticeably faster when shifting to large gears.
Often, most of the problems with derailleurs are based on the increased friction in the cables that control them. This usually leads to a slower switch response when switching to small stars.
The most problematic part of the cable is the loop that runs from the top stays to the rear derailleur. The place where the cable comes out of the jacket is often dirty. The resulting corrosion greatly complicates the smooth running of the cable and, as a result, impairs the clarity of switching. The rope loop should also be smooth enough. A loop that is too short causes the rope to travel in a smaller arc and thus increases friction.
Another area where the cable is also exposed to excessive moisture and dirt is the bottom of the carriage, where the cable runs up to the front derailleur. The increased coefficient of friction here causes chaotic switching of the drive gears under load.
Discrete switches use a special non-compression cable with several smooth layers between the cable and the outer plastic sheath. For the brake cable, the jacket is based on a metal coil. Therefore, special wire cutters are required to work with the derailleur cable.
When the cable jacket is cut, the plastic layer inside shrinks. In this regard, it is best to use an awl to make the hole for the cable straight.
When cutting off the cable jacket, which will subsequently bend noticeably. for example, a piece of cable that fits the rear derailleur. it is recommended to first bend the jacket to the desired shape and only then cut it. There are many small metallic hairs inside the shirt. If you cut a straight shirt, all internal small wires will be of the same length. As a result, with a strong bend, the inside of the wires will be shorter than the outside, and the end of the shirt will bend. Also, it is necessary to have metal ferrules for the cable jacket, which allow the jacket to fit more tightly against the stop.
The use of non-compression jackets in modern cables eliminates the need to lubricate the cable along its entire length. The viscosity of the grease only causes additional resistance. However, it is recommended to use medium viscosity oil on the ends of the jackets and where the rope has a strong bend.
There are different models of cables, differing in quality. It is best to use only high quality cables.
This method only works if a bike rack is used, otherwise you will need an assistant to work.
With your right hand, you need to rotate the pedals forward, while with the left hand move the rear derailleur forward to the frame. After the chain is on the third small star in a row, stop the pedals and release the switch. Under the influence of the force of the spring, it will move back to its original position, but the chain will remain in the right place.
Then, grasping the end of the cable, pull it in such a way as to re-align the chain. Next, the anchor bolt is fixed and the clarity of the switching is checked. This method allows you to do virtually without fine-tuning the switch.
Replacing the front derailleur cable
Run the cable from the shift lever through all shirts. Before that, it is worth checking the condition of the shirts, especially at the end points. Next, you need to pull the cable and put the switch lever in the extreme position. This corresponds to the position of the chain on the smallest star.
How To Disassemble/Assemble A Rear Derailleur
The cable is then inserted into the mount on the switch and secured with an anchor bolt. In the event that 3 drive sprockets are installed, a finer adjustment of the cable tension will be required for a clear shift to the middle sprocket. For this, an adjusting drum is used.
Bicycle speed switches: device and how they work
What are gear shifters, what are their main problems, and is it worth buying a new expensive gear shifter to improve gear shifting clarity?
Tighten the cable firmly with pliers and tighten the anchor bolt. Then adjust the clarity of switching with the adjusting drum.
It is important to set it up especially accurately, since if the adjustment is not good enough when switching speeds, the chain can fly off or even break. The sequence of your actions will be as follows:
Use the rear shifter to shift to the middle sprocket so that the chain is not too skewed.
Next, put the chain in first gear and unscrew the bolt securing the cable.
Use the screw “L” to move the transfer frame so that the distance from the chain to the switch on the left and right coincides.
Without too much tension, place the cable and secure with the bolt.
Switch to the biggest star in the front.
Tighten the screw “H” so that the chain is again exactly in the middle of the frame.
Check adjustment results and achieve maximum shifting accuracy with the thumb on the shifter.
If the shifter triggers are too tight, loosen the cable tension.
Bicycle speed switch how to disassemble
Dusty grease in derailleur rollers
The second version of the worn out rollers is more sophisticated and perverse. I already wrote that the previous owner of Trek Eqinox E7 simply smeared a thick layer of grease on the chain. And this grease not only clung to the dust, it also crammed into all the cracks. That is, this abrasive grease gets into all bearings. After disassembling the roller, I saw that it was jammed into a brass plain bearing.
Killed and new outer rollers of the rear derailleur Shimano 105
As a result, the bearing was crushed and bored (the teeth on the roller were completely intact) and the roller began to play on the axle. He played to such an extent that in the extreme left position he reached one asterisk, and in the right. to the second. At the same time, the switch itself was in place.
Killed and new Shimano 105 idler rollers
I had to get new rollers from Shimano XT (fortunately, I had a kit “just in case”. and put instead of the dead ones. The outer (Narrow) new roller was on the industrial bearing, the old one was just sliding. The new guide roller (G-Pulley) was on the ceramic bearing, that is, almost eternal, if not lubricated
We use ABRO THREADLOCK thread lock for assembly
The frame on the Shimano 105 derailleur is made of aluminum, so do not over-tighten the mounting bolts. The favorite thread lock was taken, applied to the bolts. After that, the bolts were tightly screwed into the holes. Watch the effort very closely, I repeat. Simply if you rip off the thread in the aluminum frame, it will be very difficult to restore it. You can, of course, screw in an ordinary bolt and nut there, but this is somehow unkosher
As a result of all the work, we get an assembled rear derailleur, completely ready for work How to set up and adjust it. in the next entry.
Have you ever fingered the rear derailleurs yourself??
Dish of the day: Swing under the waterfall Interesting. the water turns on depending on the position of the swing, or you have to “fall” in between?
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How to fix a bicycle rear derailleur
- – Hexagon wrench set;
- – Open-end wrench or key-bone;
- – Pliers;
- – New cable for the derailleur (in case the old one has fallen into disrepair);
- – Graphite grease;
- – Nippers;
- – Phillips screwdriver;
- – Rag for cleaning parts and hands.
Wipe down the rear derailleur and remove any dirt. If grass or branches are crammed into the switch, be sure to remove them before starting repairs.
Turn the bike over and place it on the handlebar and saddle so that you can pedal freely.
Remove the hex screw or cap screw that holds the cable down. It is very easy to recognize it, since the cable fits exactly there, and this is one point for the entire switch.
Take the released cable in your hand, examine it carefully. If the cable is intact, it is not damaged. it does not unravel, all the fibers are in order, and there is only a small mark on the cable, then go to step 5. If the cable is damaged. it needs to be replaced with a new one.
Hold the cable with your hands, switch the lever on the handlebar and see if the cable moves with each click. If there are no dips or wedging in the cable, proceed to the next step. If the cable gets stuck somewhere, you need to remove the jacket from it and grease it with graphite grease.
Put the shirt back in place. Set the cable aside. Go to the switch. There is an L and H screw on the switch (they are signed on most models).
We rotate the bicycle pedals. Since the cable is not locked, the chain must move to the end position. If this does not happen, turn the screw L with a screwdriver (in both directions, we look at the situation) until the chain lies confidently on the extreme star. No deviations allowed!
Only after step 7 is performed correctly, do we move on to tightening the cable. The cable rests against a special thrust bearing on the body (so-called fine adjustment). Before inserting the cable back into its position, the thrust bearing must be tightened almost completely, leaving 2-3 turns free.
We insert the cable into its position. Using pliers, pull the free end, tighten the cable and fix it with a nut or hex bolt. Everything is almost ready. It remains to adjust the screw H.
We shift the gear to the last, largest rear sprocket. Ideally, the chain should switch freely and stay on this star. If clicks occur, or the chain does not lie on the star, it is necessary to turn the screw H left and right with a screwdriver to find its optimal position. If you set the position incorrectly, the last gear will not be included or vice versa. the chain will collapse between the cassette and the hub flange.
There is also another bolt on the switch, which most likely will not be required. It determines the longitudinal position of the switch. It is easy to find as it is located close to the switch axis and rests against the cock. This bolt only needs to be turned if the chain slips under load during movement.
The task is completed, your switch is configured. It’s actually very simple. so don’t be afraid to repair the switch yourself.
Note that if the derailleur is incorrectly set, the chain will fall between the sprockets on the cassette. Because of this, there will be a clicking sound, chain overshoots will appear and the chain itself may break. The determining factor in the repair and adjustment is the setting of extreme positions.
You also need to remember that switching problems are not always associated with the switch. it is likely that the chain is already too worn out and slips by itself or the teeth of the cassette have grinded.
Using different bike speeds helps maintain a certain rhythm of leg movement while riding, which avoids increased stress on the body. The speed switches, which are located on the steering wheel, need to be adjusted periodically. This problem is especially true if the bike is equipped with position switches.
Install the derailleur so that it is parallel to the star system. The distance between the largest sprocket and the derailleur strip must be between 1 and 3 millimeters, inclusive. Shift the left shifter to first gear and place the chain on the smallest sprocket. Make sure the cable that moves the front derailleur is taut. Raise your bike. While pedaling slowly, shift the shifter to second speed. Make sure the chain goes over to the middle sprocket when doing this. If the chain is still in the same position, tighten the screw on the shifter to tighten the cable on the front derailleur. Try shifting the shifter back to first speed. If the chain does not move to the small sprocket, re-adjust the cable. Ultimately, you need to tighten the cable so that the derailleur moves freely both up and down. Crank the pedals slowly and check that all bike speeds are operating when shifting the shifter forward and backward. Adjust the rear derailleur. With the chain on the rear wheel on the small sprocket, shift the shifter to the maximum position. In this case, the line of the derailleur rollers should be parallel to the smallest star when viewed from the back. Turn the stop bolt marked “H” one turn. if necessary, gently bend the derailleur so that the rollers are parallel to the small sprocket. Shift the shifter sequentially from a higher gear to a lower one to check for proper chain shifting. If the chain jumps over one gear or remains stationary, adjust the cable tension. Repeat these steps checking each star.
Transmission repair steps
Repair includes adjusting the front and rear derailleurs, as well as checking the condition of the cables, chain, cassette and rollers.
- Unscrew the bolt holding the cable.
- Disassemble the shifter and remove the cable from it and from the shirts. Shirts are also recommended to be replaced!
- Clean shirts and put a drop of oil in them for better cable glide.
- Thread the new cable through the shifter and then into all shirts.
- Start configuring the switch.
- Bite off the excess part of the cable and secure the end with a special tip.
If you see that the teeth of the transfer rollers or cassettes have worn out, they must be replaced with new ones. Worn cassette or rollers rotate the chain, and the quality of gear shifting on the bike suffers greatly.
Over time, the chain deteriorates. It is recommended to keep several chains in stock and change them every 100 kilometers, because the wear of the chain will deteriorate the cassette. Multiple chains will wear out more slowly and your cassette will last longer. You can determine the state of the chain using a special tool. It is impossible to repair the chain, you just need to replace it if necessary.
If the chain is in good condition, simply remove it, clean and lubricate. Remove excess with a napkin or dry cloth.
This device allows you to set the degree of chain wear
What to do if your bike’s derailleur is broken
Transmission components must 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.
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.
Make sure the cock is level first. If it is still bent, you can contact the service to straighten it, or try it yourself. Alternatively, you can simply replace it. For 2016, for roosters are only about 300-900 rubles. Do not even try to tune the derailleur with a bent cock, as the gear setting on the bike in this case will not work for you.!
Some firms produce the so-called cock guard, which is attached to the frame. Do not buy it under any circumstances! A rooster is a consumable component that can and should be replaced if it breaks. When hitting this very protection, the cock will remain intact, but the frame may crack. The frame is harder and more expensive to change.
When you are convinced that the rooster and the cable are in good condition, you can proceed to the actual setting.
Place the chain on the largest chainring in the front and the smallest in the back.
Remove the bolt that holds the rear crossover cable.
By rotating the bolt with the inscription “H” you need to make sure that the switch rollers lie in the same plane with the desired sprocket.
Then lightly stretch the cable and tighten the bolt holding it. Over-tensioning the cable will make the crossover difficult to work.
Shift the speed to the lowest (i.e. the largest star in the back and smallest in the front).
Rotate screw “L” until the derailleur rollers line up against the large sprocket.
Check if gear changes are good.
If shifting is not correct, use the thumbscrew on the shifter, which changes the cable tension.
Now that you have set up the rear derailleur, you are ready to adjust the front.
How to repair a Shimano rear derailleur
If, while driving, something starts to click, and the gears are not changing clearly, then usually we begin to adjust the rear derailleur. Sometimes it doesn’t help and it means that it’s time to fix it.
In fact, it may turn out that it will not be possible to repair it. This happens if the switch is pulled into the spokes and the frame is skewed. Sometimes, the frame itself begins to play, and it is already impossible to accurately position the rollers above the stars of the rear cassette.
If everything is ok, and the frame is straight, and there is no backlash, then here it is already worth looking at the guide rollers themselves. They can either grind off or start to play on the axles.