Speed change mechanism
The operation of the rear and front derailleur is as follows: if the cable is pulled, the derailleur frame moves the chain to higher sprockets. If, on the contrary, weaken the cable, then the frame will throw the chain onto smaller stars.
The speeds are switched with the help of shifters (coins) located on the steering wheel. The rear derailleur is adjustable with the right shifter. Thus, the chain jumps between the rear sprockets. And the front derailleur is adjustable with a shifter on the left side. So the chain jumps among the chainrings.
What can affect the quality of the switches
It is important to find out what caused the problem.
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.
Rooster bent or broke
If the foot of the rear derailleur is oblique, then the mount is bent. You can fix this defect yourself.
- Hold the foot with one hand and grasp the switch with the other.
- Carefully, without sudden movements, align the position of the rooster until the rear frame is level.
The rooster should be replaced with a new one as soon as possible. Even if you have aligned it, such a detail will not last long.
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.
Internal gear shifting for mountain bike
The basis of this design is planetary bushings. This mechanism does not use cassettes. The transmission includes only 2 stars: front and rear. The whole mechanism is hidden inside. Usually there is no front derailleur either.
HOW TO MAKE A SHIFT KNOB
All elements of the gearshift are hidden in the body
Brake Housing & Cable Installation. Drop Bars
This mechanism is often found on road bikes, pleasure bikes, folding bicycles and city bikes. The system itself is located inside the rear planetary hub. This type of shifter can be seen, for example, on the Forward Surf city bike (3 gears).
This mechanism is difficult for a layman to adjust. Better contact a bike shop if necessary.
When speed adjustments are necessary
The bike speed system needs to be adjusted if not all gears are engaged or the shifting is incorrect. This can happen as a result of:
- replacement of one or more transmission elements (chain, cassette, roller, bearing, etc.)
- wear (stretching) of the cable or shirts
- deformation of parts due to impact or falling
Sometimes additional adjustments are required after buying a bike. It is recommended that you wash your shirts before adjusting the speeds on your new bike. To do this, pull the cable with moderate force wherever it is exposed. After mechanical action on the cable, you will see that it began to sag. Release the cable on the rear derailleur, tighten the adjustment on the shifter and re-fasten it.
Before setting the speeds on a used bike, clean all the transmission elements from dirt and dust, lubricate the spring, cables and chain. The chain width must match the front derailleur for proper derailleur operation. Strong play of the switch and carriage bearings is unacceptable. Make sure the stars of the system are perfectly even and rotate in the same plane.
Preparation for commissioning
Before adjusting the bike speeds, you need to clean and lubricate the chain and derailleurs. It is also advisable to produce:
- inspection of the drive cable for the presence of rough bends that violate the smoothness of its movement along the inner surface of the shirt, unweaving and solidity of the connection with an emphasis based in the shifter;
- control of the condition of the jackets. in case of strong wear of the inner, often silicone insert, or the presence of fatigue fractures, their replacement is required;
- inspection of the rear derailleur and the counterpart of the frame (cock) for deviations from the vertical position. the rollers and the counter sprocket of the cassette must lie strictly in the same plane.
Also, before adjusting the speeds on the bike, it is necessary to loosen the cable tension and it is strongly recommended to turn the adjusting drums all the way. In the already tuned state, the following dependence is observed: the less the drum is unscrewed, the more accurately the system works, and also a guaranteed departure margin is maintained, which is necessary for instant compensation of the cable lengthening during the trip.
Initial checks on a rear bicycle derailleur begin with the derailleur mechanism. complex than the front, it can hide more problems in itself than can be corrected with a tweak:
The rooster is a special attachment, and, being usually a separate part from the frame, the rooster is damaged by falls and even serious loads, therefore it is very important to check its parallelism to the frame and, in general, its integrity. Recoil spring. its defects are often perceived as problems with the cable jacket, as they look the same: switching on the loosening of the cable becomes problematic
The springs are usually changed along with the entire device. The cable feed is a secondary test, on many derailleurs, especially budget Shimano, the cable runs into the rear derailleur from the back, creating a kind of “loop”. It is on it that damage usually appears, since this point is easy to damage when falling or driving on the grass.
Adjustment screws and cable attachment to rear derailleur
Shimano also makes SORA and TIAGRA road derailleurs. Speaking of shifters, it’s also worth touching on the shifters (the shifters on the handlebars). On children’s and budget bicycles, revolving-type shifters are often installed, the switching of which is carried out by a simple rotation like a throttle on a motorcycle. The advantage of such shifters is that they have a low cost and you can quickly switch to several gears with one rotation of the brush.
The downside is that it is difficult to switch to a certain gear, and there is a possibility of accidentally switching, inadvertently taking the wheel. Therefore, the most common are trigger shifters.
It is very easy to change gears with such shifters. The two levers are under the index and thumb on Shimano, and both under the thumb on the Sram. Once you’ve ridden a bike with this shifting system, you’ll instantly know which lever is down and which is up. In addition, on road bikes there are switches on the frame, as well as combined with a brake lever.
Sometimes you will find derailleurs right inside the rear hub, unlike the familiar derailleurs that are attached to the cock and throw the chain over the cassette. This is a planetary hub. These bushings are most commonly seen on road bikes. The advantage of such bushings is that the switching takes place without sudden jumps in the chain, which is very convenient, besides, dirt does not get on the working parts, as a result of which the switching is not so dependent on the external environment. Also, switching in the planetary hub occurs without pedaling, which means that you can switch even while standing still. The disadvantage of such bushings is that they weigh a lot, and most importantly, it is difficult to find a service that can repair them, and even more so, they cannot be repaired on your own during the trip.
If the chain slips with effort when pedaling, it means that it is stretched and it is time to change it. If you haven’t changed it for a long time, you may also have to change the stars with the cassette. a worn out chain quickly destroys a star.
If some certain speeds turn on poorly, check if the cable runs freely in the shirts and if there are any breaks, as well as places with unbraided cable winding. Shirts with breaks and those in which the cable runs with difficulty must be replaced, as can a damaged cable. The same problem can be caused by a bent cock.
If the switch suddenly stopped working altogether, then the problem is definitely in the cable: either it is badly tightened with the fixing bolt, or it broke.
And another important point. When changing gears, make sure that there is no skewing of the chain, due to its location simultaneously on opposite sprockets of the connecting rod and cassette, as well as on the middle sprocket and extreme sprockets of the cassette. Incorrect chain positioning is shown schematically in the picture. Because of this, there is a rapid wear of both the chain and the sprockets.
In general, setting up your bike’s gear shifters is quick (30-40 minutes) and effortless.
Rear derailleur fine adjustment
From time to time, you will have to fine-tune the rear spreader in the following cases:
- If repairs, replacement, adjustment of chain drive units were carried out.
- New cables and shirts installed on the bike.
- Low-quality cables stretch strongly during operation, and plugs at the ends are squeezed out of the jackets.
Switch adjustment is performed by unscrewing the hollow cable tension screw half a turn to the left. It is easier to unscrew the screw when the cable tension is released. when the shifter is reset to the highest speed. Be sure to check the accuracy of the installation while riding a bike.
Setting the low gear limiter
We adjust the adjusting screw for low gears, marked L. At the front, we set the chain on a small star, at the back. on a large one. We tighten the screw L so that when the wheel rotates, the chain slightly clings to the far lower frame of the switch. As soon as you feel the chain rubbing against the frame, loosen the screw a quarter turn.
Types of shifters, their differences
Initially, bicycle shifters worked on the principle of sliding the cable and fixing the cable with a nut. Here, the gear was determined by the tension on the shifter body, approximately as described above. Later, ratchets began to be installed in them, and the method of changing the position of the cable is called index.
Modern bicycle models are equipped with several types of drive mechanisms:
- brake. Dual control;
Gripper shifters change the cable tension by moving the drum around the steering wheel axis. The movement is carried out back and forth, in the center there is a pointer along which the gear is set. Other models can be equipped with an arrow display.
The advantages of these shifters include the geometric integrity of the devices, the absence of protruding parts and instant response when the drum moves. It is noted that grip shifts are easy to operate.
- random switching;
- take up a lot of space on the steering wheel;
- the swivel mechanism of budget models breaks easily.
Triggers are the second common type of shifters, where shifting is carried out by means of protruding levers: tension and release. The first upshifts, the second downs. Front and rear shifters work opposite to each other: the front up lever is down for the rear, and vice versa.
- clear operating principle;
- levers are light to the touch, do not distract from control;
- there is no risk of accidental switching as with grip shifters. hands on grips do not touch the shifters.
Of course, there are disadvantages, taking into account which grips are better than triggers:
- if the bike falls, the levers may break;
- tight pulling of the cable on fast transitions through 2-3 gears, which causes a delay in switching;
- incorrect alignment with the brake pincers (however, this is more a “joint” of the bike manufacturer than shifters).
Triggers come in several flavors:
- lever and button above the steering wheel (Ez-Fire Plus). budget “Shimanov” models;
- with steering column placement of levers (Rapidfire). Shimano high class;
- Trigger: SRAM single lever shifters, new SRAM models with lever and button.
Dual Control, or brake shifters, are activated by moving the brake lever in a perpendicular direction. The novelty was presented by Shimano. Compared to the previous types, drive devices of this type are used in narrow circles and are installed on expensive foreign models.
Dual Control does not interfere with the bike’s control even when the grip is moved. Also of great interest is their design, where the brake claw has two degrees of freedom. We can say that shifters of this type are integrated into the brakes. Along with this, there are a number of serious disadvantages:
- cannot be installed on hydraulics;
- poor compatibility with rear derailleurs;
- are put only “from scratch”.
Pistols. shifters specifically for racing bicycles. Their design is similar to Dual Control in that the gearshift mechanism and brake actuator are integrated and controlled by a single lever. To brake, you need to pull the lever back to increase the gear inward, and to lower it, press the auxiliary lever under the claw.
A significant advantage of this mechanism is the ease of control in any grip, the disadvantages are the high price and low braking force.
What are the best bike shifters
Every owner of a high-speed bike knows what a bicycle shifter is. These devices are directly involved in gear shifting, with their help the cyclist easily and simply controls the transfer of the chain through the cassette stars. The detail is small, but it depends on its state whether the bike will be fast, as it should, or it will “get stuck” in one gear.
How to independently replace and sort out the shifters on a bicycle
Sooner or later, the shifter may stop working correctly or even refuse to serve further. Pulling or loosening the cable may not solve the problem, so the old mechanism will need to be replaced.
New shifters come assembled with a cable, so you don’t need to assemble them from scratch. All operations are reduced to removing the old part, installing a new one and the obligatory adjustment of the switches.
- Removing the grips from the bicycle handlebars. They are often thicker than the grip of the shifter yokes and will interfere with removal.
- Disconnect the gearshift cables from the derailers.
- Loosen the mounting bolts and remove the shifters from the steering wheel.
After that, you can put new parts on the bike:
- Attach the shifters to the handlebars. Do not move the brake levers during operation.
- Gently thread the cables through the frame to the derailleurs.
- Connect new cables.
- Adjust switches, test new shifters. Adjustment must be done with both cables attached to the switches.
If the shifters do not work very well, they get stuck on shifts, you can use the alternative option. bulkhead, cleaning and lubrication. In the event of a malfunctioning part, you can put it from a similar model, then this is the repair of the shifter. In any case, you will have to disassemble it, and how to do this, we will find out further.
Bulkhead and repair using the example of Shimano shifter: 1. Unscrew the bottom cover bolt, pull it out.
Remove the top cover, which contains the speed indicator.
We get to the ratchet mechanism with dogs. Common problems, which can be: entry of antennae, dirt or lack of lubrication. In the first case, further disassembly makes sense if you insert a new washer with antennae from another shifter.
We take out the pressure piece and levers.
Unscrew the screw that holds the case.
We remove the case, take out the ratchet mechanism with a cable.
Separating the ratchet from the plastic washer.
There is a pull-up dog on the body near the cable fixing, it should not be disassembled, since it will be quite difficult to assemble.
Disconnect the levers: pry the springs at the junction of the levers with narrow claws.
We carefully wipe and lubricate all the parts of the shifting mechanism. Installation is in the reverse order.
How To Install A Bicycle Shift Lever And Gear Cable
This is how the shifter is being repaired using an example. The most important thing in work is to keep all the details separately from each other in the field of view.
What are shifters, and how are they arranged
Shifters are gear shifter actuators attached to the handlebars of a bicycle. Modern high-speed bikes are 90% equipped with two shifting systems. front and rear. respectively, each equipped with its own shifter. On the left handlebar is the drive mechanism for the front derailleur, on the right for the rear.
In the classic 3 X 8 gearshift system, there are 2-3 rear sprockets for each chainring. By analogy, one division of the left shifter includes 2-3 divisions of the right. Single shifter bikes (rear cassette only) or planetary hub have one shifter on the right hand side of the handlebars.
The professional name for these devices is shifters. Their internal structure is quite simple, it includes several mating parts:
- drive handle;
- movable block;
- free lever;
- shift cable;
- spring ratchet lock.
The handle, which is operated by the cyclist, causes the position of the free arm to change. That, in turn, moves the block on which the gearshift cable is wound or unwound. The spring clip performs the function of securing the position of the cable on the drum block and does not allow the switch to independently throw the chain.
Thus, by changing the tension of the cable on the block, the corresponding gear is set. It is imperative that the shifting mechanism is fine-tuned, and one division on the shifter corresponds exactly to the chain tossing exactly one sprocket. If the shifter works properly, but the gears do not shift or skips two or three, then it is necessary to adjust the speed switch.
So, in this article we learned how the bicycle shifters are arranged and work, what types they are divided into, their pros and cons. It will not be difficult to change the shifters on your own to new ones, disassembly should also not cause any difficulties.