Adjusting the front derailleur of the bicycle is one of the most complicated maintenance procedures, as it is a matter of millimeters. If you have problems changing gears or you notice the chain rubbing against this structure, you don't have to take your bike to the bike shop for repair. All you need is a "good eye" and some tools. With patience and experience, you will be able to change his position like a pro.
Steps
Method 1 of 2: Troubleshoot Exchange Issues
Step 1. Recognize a well adjusted front derailleur
Your goal is to place it comfortably on top of the chain so that the outside of the cage is 2-3mm from the largest sprocket. In addition, it must be aligned to allow its curved profile to be parallel to the links in the chain. The cage must be parallel to the chain.
If the front derailleur scratches against a ring or gets caught in some element, do not ride the bicycle. In such cases, read the next section: "Resetting a Malfunctioning Derailleur"
Step 2. Check for the problem
Turn the bike over so that it rests on the saddle and handlebars. Move the derailleur up and down as you turn the pedals with your hands. Can it reach all the cogwheels? Do you notice any noises of friction, clicking or rubbing? Make a note of any problem areas to remind yourself of as you go about adjusting. Be sure to check the cables and guides as well.
- If the front derailleur does not move when you shift gears, the cable may be damaged. If so, replace both the cables and guides, especially if you notice any cracks, fraying, or nicks.
- Place the chain on the lowest gear at the front and release the tension from the rear derailleur. Check the cable and adjust the tension until you feel it slightly pulled.
- Reposition the derailleur if it appears to have warped. Replace the derailleur or rear derailleur in case they are broken.
- Check the rear derailleur and, if necessary, adjust it before continuing.
Step 3. Select the lowest ratio
Verify that the chain is located on the center rear gear and on the smaller front gear. This way, you are sure that the chain is not stretched diagonally and, at the same time, that the derailleur cable is loose and easier to manage.
Step 4. Loosen the cable bolt while holding the wire taut
Right above the derailleur you can see a thin metal cable locked in place with a small nut or screw. It is usually attached to the bicycle frame. Grab the top of the cable and tighten it as you loosen the nut; pull the wire to tighten it and then tighten the bolt again; in this way, close the nut and the cable will not be able to move.
This maneuver moves the front derailleur slightly, but you will be able to adjust it again soon. For now, just make sure the cable is taut so that the whole mechanism works smoothly
Step 5. Locate the adjustment screws
At the top of the derailleur or on its sides there should be two small screws identified one with the letter "L" and the other with the "H". You will notice that they are not fully tightened and protrude slightly. These allow you to control the amplitude of the left and right movements of the cage. They can generally be screwed on and off with a normal Phillips screwdriver.
- The screw marked "L" controls how far the cage moves towards the frame. The screw with the "H" controls how far the cage moves outward.
- If the screws are not labeled with a letter, you can do a simple test. Move the chain onto the smaller sprocket and turn a screw fully in both directions, observing the movement of the derailleur. If the cage moves, then it means it is the "L" screw; if it doesn't move, you are turning screw "H". At this point, you can use a marker to identify the two screws and not have to repeat the test in the future.
Step 6. Line up the bottom end of the front derailleur
Bring the chain onto the smaller front sprocket and the larger rear sprocket. At this point, the chain is in its far left position. Turn the screw "L" so that the cage is separated from the chain, on both sides, by about 2-3 mm.
You should be able to see the movement of the derailleur as you turn the screw
Step 7. Align the top end of the front derailleur
Rotate the pedals and bring the chain onto the larger front sprocket and the smaller rear sprocket. At this point, the chain is in its far right position. Turn the screw "H" so that the cage is at a distance of about 2-3 mm from the chain on both sides; doing so gives her plenty of room to move.
Step 8. Adjust the rear derailleur by bringing the chain to the sun gear and then test by changing the front ratio
Change the rear ratio by sliding the chain on a center wheel, so that it does not suffer any traction as you change the front. Next, spin the pedals and move the chain from one sprocket to the other several times to check for problems. If necessary, readjust screws "H" and "L"; finally, go out and enjoy a nice ride with your bicycle.
If you over tighten or loosen the "L" and "H" screws, the front derailleur may slip; however, you should be aware of this problem before testing the changes made
Method 2 of 2: Reset a Malfunctioning Derailleur
Step 1. The front derailleur must be reset when it hits the chain links or when it is bent or angled in an odd way
The adjusting screws are unable to solve the major problems, for this reason you have to reset the derailleur and start over if you notice that the cage is tilted, too high or touches the chain.
Step 2. Bring the chain to the far left sprockets
This means using the smallest front gear and the largest rear. In addition, the bike must be placed on a special workbench or turned upside down, in order to turn the pedals and change gear with a single movement.
Step 3. Loosen the adjustment barrel to remove tension from the cable
This barrel is located at the end of the derailleur cable, near the handlebar. To find it, follow the path of the wire until you spot a small barrel structure that rotates on itself. Turn this structure clockwise until it stops.
Count the number of rotations of the cylinder because, once the work is finished, you will have to bring it back to more or less the same position
Step 4. Slightly loosen the bolt securing the derailleur cable
Right above the cage is a cable that connects it to the gear lever on the handlebar; this metal wire is held in place by a small bolt or nut that prevents it from moving. Unscrew the bolt just enough to allow the cable to move when you pull it, without letting it slip by itself.
Step 5. With great care, unscrew the nuts that secure the derailleur to the bike frame
However, avoid it moving excessively, because every large movement of the whole mechanism changes the entire alignment. Loosen these nuts just enough to loosen the derailleur slightly from its original position.
Step 6. Move the whole mechanism to the correct position
If the cage is tilted, rotate it until it is parallel to the chain, being careful not to change its height. If it comes into contact with the top of the chain links, move it a few millimeters so that it is slightly above the larger sprocket. Your goal is to ensure that:
- The cage is located 1-3mm above the largest sprocket. You should be able to slip a dime between the outside of the cage and the gear teeth.
- Both sides of the cage are parallel to the chain.
- The curve of the cage is parallel to that of the sprockets.
Step 7. Arrange the cables and adjust the adjustment screws
Once you have made the changes, you need to adjust the derailleur so that the chain moves from one sprocket to the other smoothly. To do this, tightly tighten the cable and tighten the lock nut. You can now operate the adjustment screws as described in the previous section.
Lubricate the chain so it runs smoothly between sprockets. Also remember to re-tighten the adjustment barrel
Advice
- You can keep a pair of pliers on hand to keep the cable taut.
- Remember to move carefully, tighten each screw / bolt and test them. Avoid turning the screws and changing the position of the front derailleur in an exaggerated way, otherwise it will be difficult to restore everything to its original condition in case of problems.
- You may also find it helpful to know how to adjust a bicycle's rear derailleur.
