If you have difficulty changing the gears of the bicycle, the chain does not stay on the chosen sprocket or it falls, you need to adjust the gears. Derailleurs are devices that allow you to change gear by pulling and pushing the chain on different gears each time you shift. Although it may seem like a complicated task, adjusting the bike gear is not difficult, if you arm yourself with patience and have a little experience.
Steps
Method 1 of 2: Adjust the changes
Step 1. Lift the bike off the ground by placing it on a kickstand
The wheels must be able to turn freely without moving the vehicle. The best way to do this is to use a specific tripod; if you don't have one, ask the bicycle or sporting goods shop if they provide a "do it yourself" maintenance service that allows you to access their workshop for a small fee.
- You can also turn the bike upside down so that it rests on the saddle and handlebars; if so, remember that you need to rotate the elements in the opposite direction from what is described in this article.
- If you have the possibility, you could hang the seat from the hollow of a tree or from a beam that is not too high.
Step 2. Locate the derailleurs
They are mechanical devices that physically allow you to change gears and hold the chain in place. One is connected to the sprocket set (the set of gears), while the other - smaller - is mounted near the pedals. Check that there is no object stuck between the mechanisms, such as leaves, sticks or mud; in this case, clean with a damp cloth.
- The rear derailleur is the most complex element and is composed of a derailleur, a rocker arm and one or two small sprockets, on which the chain is slid. A cable pulls the rocker back and forth letting the chain run from one gear to the other.
- The front derailleur is fixed to the bike frame and is composed of a spring and a "cage", ie two metal walls that force the chain to stay on only one gear at a time.
Step 3. Diagnose problems by inspecting one gear at a time
Turn the pedals slightly with one hand and shift gears slowly, starting with the rear sprocket set. Slide the chain on each sprocket, both increasing and decreasing the ratios; take note of the problematic points, the areas where the chain tends to slip or those where you are forced to operate the control twice to pass the chain from one sprocket to the other.
As you check out one derailleur, leave the other in the center position. For example, if you are inspecting the rear system and your bike has three front gears, you must leave the chain on the middle one during the entire procedure; in this way, the chain is not subjected to unnecessary tension
Step 4. Locate the cable adjusters
Follow the path of the cables leading to the derailleur until you find the adjusting screws, which look like small bolts or cylinders surrounding the cables themselves. There should be two for each cable - the first near the derailleur and the second on the handlebar lever. These devices allow you to slightly adjust the cables while making minimal changes to the transmission system.
Step 5. Bring the chain to the "problem relationship"
Operate the shift lever while turning the pedals with one hand, until you encounter the malfunction: for example, the chain does not change gears, fails to stay on the same or "jumps" to the next sprocket. Stop switching gears when you encounter the problem, but keep the chain on the "offending" gear.
Step 6. Loosen the cable adjuster if the chain does not shift down
If you have trouble switching to the larger gears (the ones closest to the wheel), you need to loosen the cable adjuster by turning it counterclockwise; turn it slowly, until the chain falls on the right sprocket.
- Always work calmly, operating the regulators a quarter turn (maximum) each time.
- Imagine this operation as if you wanted to rotate the adjuster in the direction you want the chain to move; turn it towards the bike if you want the chain to go in the same direction.
- Do not loosen the adjuster too much or it may come off the front derailleur. If you need to tweak it considerably, slide the adjuster into the derailleur, shift to lower gear, loosen the bolt, and pull the cable by hand.
Step 7. Tighten the cable adjuster if the chain does not shift to higher gears (the smaller gears)
If you can't get the chain to higher ratios, you should tighten the cable adjuster by turning it clockwise. When you reach the correct tension, the chain should fall by itself onto the appropriate sprocket.
Again, imagine turning the adjusting screw in the same direction you want the chain to move; rotate it away from the bike to move the chain outward
Step 8. Select the lowest gear and then operate the lever to slide the chain through all the gears, down to the smallest and then back to the largest
When you have managed to fix this type of malfunction, test all the gears to be sure that the front derailleur is able to move the chain in each position.
The chain should slide smoothly from one sprocket to the other every time you shift
Step 9. Take a short test drive to make sure there are no other problems
Sometimes, bicycles behave differently when supporting the rider's weight. Ride your bike in a parking lot or along the driveway, repeatedly shifting gears. Take note of any malfunctions and adjust cables accordingly.
Method 2 of 2: Repair the Stuck or Slipping Chain
Step 1. Lift the bike off the ground by placing it on a kickstand
The pedals must be able to rotate without the bicycle moving. The best way to do this is to use a specific tripod; if you don't have one, ask the bike shop or sporting goods shop if you can have access to their shop, in exchange for paying a small commission.
You can also turn the bike upside down by placing it on the saddle and handlebars; if so, remember that you need to rotate the elements in the opposite direction from what is described in this article
Step 2. Bring the chain to the lowest gear
If you are working on the rear derailleur, this means putting the chain on the smallest sprocket farthest from the bike; if you are working on the front derailleur, you need to make the chain slide on the smallest sprocket and closest to the frame.
Bring the derailleur that Not you are adjusting on a central gearbox.
Step 3. Unscrew the bolt holding the cable in place
This is located at the end of the cable itself, which runs from the handlebar to the derailleur. There is a small bolt that secures the cable and holds it taut; use an Allen key to unscrew this bolt and free the end of the cable.
Important note: By turning the pedals, you can notice that the chain slips to the smallest gear without the need for help. The cause of this behavior is the derailleur, which works by stretching the cable to keep the chain in position; for the same reason, you can change gear manually by pulling the cable.
Step 4. Locate the "adjustment screws"
To prevent the chain from slipping, the front derailleur is installed in a small area between the gears. There are two small screws that hold it in place and are located close to each other on the top or rear of the derailleur itself (for the front and rear respectively).
- The screw on the left, often indicated by the letter "H", adjusts the upward movement (ie towards the bike) of the chain.
- The screw on the right, usually indicated by the letter "L", adjusts the downward movement (ie away from the bike) of the chain.
Step 5. Tighten the screws to prevent the chain from falling
These are simple adjustments: if the chain tends to fall to the right of the front derailleur, tighten the right front screw to prevent this from happening. Each screw adjusts the displacement towards the side on which it is mounted; tightening it (turning it clockwise) limits the movement of the chain in that direction.
Consult your bicycle manual in case screw H and screw L are not labeled
Step 6. Push the rear derailleur towards the inside of the bike as much as possible
If this mechanism exerts an excessive thrust, the chain falls from the gears towards the wheel; otherwise, it may not apply enough pressure and the chain will not shift from one gear to another. You can adjust the screws to move the derailleur and thus notice its movement.
- Tighten the left screw if the chain moves too far towards the wheel. By doing this, you prevent the derailleur from moving excessively to the left.
- Loosen the left screw if you can't slide the chain on all the sprockets. This adjustment allows the front derailleur to move more inward.
Step 7. Adjust the front derailleur so that the cage walls are on the sides of the chain
Tighten or loosen the left screw (H) after placing the chain on the smaller sprocket to prevent it from coming into contact with the cage wall.
Try to keep the chain 2-3mm away from each cage wall
Step 8. Screw in the cable fixing bolt
Bring the chain onto the smaller sprocket and stretch the cable by hand - it doesn't have to be perfect, just tensioned; secure it by tightening the bolt on the front derailleur that you loosened earlier.
You can often notice a notch on the cable where it was previously locked
Step 9. Use regulators to log reports correctly
Check that the chain passes smoothly from one gear to another, both in the front and in the back; use the adjustment pins to make the necessary changes.
Advice
- Take notes or take pictures of the bike before starting work, in case you are unsure of how to put all the parts back together.
- Make any changes gradually, in order to eventually be able to return to the previous settings more easily, in case you get something wrong.
- Regularly clean and lubricate the chain to avoid shifting issues and allow the bike to run smoothly.
