How to replace the shift cable on a bicycle?
There is no special science in shifting gears on a bicycle; at first glance, everything is simple. Two levers on the left, two on the right, or even just a grip-shift. what could be easier. But nevertheless, observing novice cyclists, one may notice not entirely correct and coordinated actions. But consistency when cycling is the most important thing! This is the only way you will be able to move as efficiently as possible on a bicycle, make maneuvers, overcome obstacles.
As an example, we will consider the most ordinary mountain bike (MTB) with three stars in front and 8-9 in the back.
Front derailleur setting
The front derailleur is even easier to adjust than the rear derailleur. It is important, however, that it is properly secured to the bike frame. When the chain is on the largest sprocket, the sprocket to derailleur frame should be 1 to 3 mm. And the frame should be parallel to the stars. If so, then you can start customizing.
Set the speed to minimum. the fastest at the back and the smallest at the front. Loosen the cable tension and turn the screw marked L (Low (where it is visible in the picture) until there is a millimeter gap between the chain and the derailleur frame. he lay in a special groove near the screw.
Now we set the maximum speed when the front chain is on the largest sprocket and on the smaller cassette, and turn the screw marked H (High) so that the gap between the chain and the inner plane of the frame is a millimeter. If, after that, the chain still reluctantly climbs onto a large sprocket, slightly unscrew the screw H.
Now we sit on the bike and try how successfully the gearshift settings went. If the chain does not shift well to low speed (smaller sprockets), twist the cable tension adjuster located on the front derailleur coin on the handlebar to loosen the cable tension. When the chain sluggishly climbs onto large sprockets, tighten the cable with the same adjuster.
Let’s immediately highlight the most common errors and problems:
- Too heavy gear is a common mistake. Many newbies even say that 44 (or even 48) stars in the front are not enough for them. It’s a delusion. Constantly spinning a heavy gear you are simply killing your knees. Try to keep track of your cadence (cadence) until it becomes automatic. You can even count the number of revolutions per minute for the sake of interest. If it is around 90-100, then this is very good. And so, gear 44-11 is enough to accelerate on the plain to
60 km / h So try to convince those who say that 44 stars are not enough for the city. By doing this, you may help to keep people healthy
Curve transmission. it is not uncommon to observe how people, without looking at the chain, include gears like 3-1.2. In this case, the chain goes to bend, its wear increases, at the wrong moment it can simply fly off. The optimum chain position is when it passes from the chainring to the rear with minimal skew. So be sure not only to make it easy to twist, but also the position of the chain. Switching under load. so even fragile girls manage to break chains, what to say about healthy men. And what a crunch at the same time. When shifting, reduce the load on the pedals to a minimum, just rotate them with ease until the chain jumps to the desired sprocket. Therefore, it always makes sense to assess the situation, possible obstacles and change gear in advance. Chain biting is when the chain is pulled up by the chainrings when shifting. An unpleasant situation in which the nib near the carriage assembly may be severely scratched. This could be due to cogging on the star, dirt, improper assembly and setup. This is another plus to why you need to watch the shift, and not just mindlessly flip the shifters. All movements should be smooth, even airy. Chain skipping. for example, you put a new chain on an already similar cassette (by the way, the chain resource
1500 km). As a result, when the load on the pedals increases, the chain slips and the pedals fail unpleasantly. This must be taken into account and travel more carefully until everything gets used to it. Even for a fairly strong cassette, the rubbing period is about 200 kilometers.
If you are new to the saddle, pay a lot of attention to pedaling, shifting, try to work with both the front and rear derailleurs. Try to choose a gear depending on the maneuver being made. For example: you slow down, but for this you will need to accelerate. Shift the gear lighter even when braking, then it will accelerate faster.
The clarity of gear shifting is highly dependent on the technical condition of the bike components. Monitor and, if necessary, replace the cables and shirts in time, the rear derailleur rollers, the switches themselves, the drive elements. the chain, cassette, front sprockets.
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.
Which cable to choose and where to find
- twisted. consists of a thin, twisted wire coated with a polymer. Inexpensive option, with a short service life;
- SIS. looks like a twisted one, only instead of a wire for twisting the jacket, strips of metal with a Teflon coating are used inside. The most popular type of cable;
- SIS-SP. consists of a shirt in which the threads are parallel. They are held together by a polymer layer. The braid does not stretch during operation. The tension is transmitted directly through the cable. Most reliable, accurate expensive variety.
Fine tuning tips
- you need to set the minimum speed, that is, at the back, the chain stands on the largest star, and in front on the smallest.
- slightly loosen the tension of the cable and turn the screw L until there is a 1mm gap between the chain and the frame
- we firmly fix the cable, before inserting it into a special groove.
- we set the highest speed
- adjustable with screw H the gap between the chain and the inner side of the frame
- we check the performance
- if the switching is tight, then we adjust with screws to the desired state
- After all the manipulations, the bicycle should be washed and lubricated all parts (chain, sprockets, etc.)
How to adjust the speed switch on a bike
It often happens that either the speeds on the bike are not switched clearly, or some new transmission elements have been installed. In this case, you will need to adjust the speed switch and it is quite possible to do this work on your own, without contacting specialized workshops.
How To Remove A Broken Shift Cable. Shimano Shift Levers
Step by step
Replacing the gear shift cable is performed in several stages:
- Change the position of the rear derailleur so that it looks at the small bicycle sprocket, cut off the rope bunk and unscrew the screw.
- Unscrew the cover until the end of the cable is visible and pull it out. To release the tip, you will need to pull back the spring.
- We take a cable prepared for replacement and install it, repeating the trajectory of the old element. An awl or a thin screwdriver is used to adjust the direction.
- We return the cover to its place. We set the switch to its original position if it has moved.
- We tighten the screw to fix the cable.
- We cut the cable, leaving three centimeters, squeezing its ends.
Possible problems and nuances
The repair of the brake mechanism does not end with the installation of a new cable. Adjustment required. Before tightening the brake cable on your bike, you need to determine how tight it is. To do this, simply lift the rear wheel, spin it and apply the brake. If the handle moves effortlessly more than half the distance from the initial position to the handlebars, the brake cable must be tightened. To do this, we pull the cable on the handle itself with a curly bolt.
In cases where the brake freely reaches the steering wheel, you need to adjust the tension near the brakes. For this:
- Unscrew the fastening screw.
- We tighten the cable with pliers.
- We fix the cable with a screw.
Cables and shirts
The cables for the front derailleur differ from the derailleur on the rear in that they can be slightly shorter, or even slightly thinner. And shirts are also divided into three types, and each shirt has its own cable.
Steering wheel switches
The switches here are exactly the same as on the rear wheel. They are absolutely no different, and even located exactly the same.
Why is there a violation of gear shifting
To understand what action should be taken to adjust gear shifting, you need to understand what causes may lead to the problem in question. Experts identify several such predisposing factors:
- deformation of the rooster;
- stretching the cable;
- deformation of the speed switch;
- malfunctioning return spring.
External Shifting on Speed Bike
The outer type belongs to most multi-speed bicycles. It is used on both mountain and city walking models. The mechanism is made up of gear shifters and stars that form a cassette or system. Variable speed with rear and front derailleurs.
This type of gear shifting can be seen on both the Forward Dortmund city bike (7 speeds) and the Forward Agris mountain bike (24 speeds). You can customize this switch yourself by examining the mechanism.
Adjusting the bike’s rear derailleur begins after you lift the rear wheel into the air using stands or mounts before adjusting the rear derailleur. Instructions for setting up the mechanism:
- In the preparatory stage, remove and clean well the cassette with sprockets and the speed selector itself. The chain should be set to the middle sprocket at the front and the minimum sprocket at the rear. To properly adjust the rooster, it also needs to be cleaned. To do this, remove dirty grease and debris from the tensioner rollers and sprockets, clean and lubricate the chain. Even after such manipulations, you can see an improvement in the operation of the switch.
- Next, you need to release the cable by unscrewing the tension screws on the shifter and spreader to the maximum. Remember to pull the cable out of the fixing screw. It is not necessary to remove it completely, just inspect and lubricate the desired parts.
- Now you can start setting the travel limit to the minimum sprocket. Position yourself behind the vehicle and gently turn screw H until the rollers and the desired sprocket are on the same line. If the installed spreader has already been operated, then for accurate adjustment you need to set the frame not strictly in a straight line of the mowing line, but slightly moving it to the right side of the wheel. With the correct setting, the chain will hold tight, and the system will work without noise.
- At this stage, you need to adjust the cable tension. Fix the cable with the fixing bolt by gently pulling it by hand, do not use tools. The cable tension is created by a hollow screw with a drum. As a result, the spreader should move along the sprockets without any problems from a single click of the shifter or click. You can set the transition between the two nearest elements, and the switching will independently adjust on the rest. In some models of the cable there is a special groove, make sure that it fits in it and does not get crushed.
- To adjust the bike’s rear derailleur, you need to set not only the minimum travel limit, but also the maximum one. Loosen screw L so that the cock can move freely. After cranking the pedals, move the chain at the back to the largest sprocket. Align the spreader until the rollers and the largest cassette element are flush.
- Finally, it remains to adjust the chain tensioner. Fix it so that it is on the largest sprocket in front and on the smallest sprocket in the back. If during rotation one of the rollers (upper) touches the cassette, tighten the tension screw. There should be a five-millimeter gap between the parts. Move the chain to the opposite position, that is, in the front there is a large star, and in the back there is a small one and check the tension in this position.
Replacing Shifters/Brake Levers/Cables/Housings On Trek 4300 Mountain Bike
Remove dirt and debris from all transmission components
- Clean the rear derailleur. To do this, we clean the parallelogram spring and foot rollers from dirt.
- Clean, lubricate and check the cable for integrity. Cleaning and lubricating the rear transfer cable is very important. This is due to the fact that excessive contamination or damage (rust or fiber breakage) greatly impairs gear shifting. This is because a dirty cable creates additional friction inside the jacket, thereby impairing shifting. After cleaning and lubricating the cable, you may not need further adjustment of the transfer.
- Clean and lubricate the bike chain. If you have a dirty and unlubricated chain, it will be more difficult to get crisp shifters.
- Clean the cassette of rear and front sprockets from dirt. Since we have cleaned all the transmission units of the bicycle, we should not forget about the star systems. If we do not clean them, the dirt from the sprockets will again adhere to the chain and derailleur rollers.
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.
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.
Causes of failure of the rear derailleur on a bicycle
Before you start adjusting the rear derailleur on your bike, you need to see if it might also be worth adjusting the front derailleur, and also identify the source of the problem:
- damage to the cable or lack of lubrication on it;
- deformation of the rear spreader fastener. rooster;
- development of a chain or sprocket system on the rear wheel;
- wedge of chain tension rollers;
- malfunctions in the shifter responsible for changing speeds on the steering device.
Removing the cable
It is not necessary to completely remove the cable, it is enough to look at it for deformation and lubricate.