Have you ever had problems where your bike changed speed unexpectedly or incorrectly? Many people have this problem, but fear trying to fix it by believing that they could make things worse. However, you don't have to take your bike to a shop so they can adjust the gears appropriately. Just adjust the rear derailleur! All you will need is a good eye and a little lubricant.
Steps
Method 1 of 2: Troubleshoot your changes
Step 1. Flip the bike so that you can turn the tires as you work
You will need to place the bike on a bike rack or flip it so that it rests on the seat and handlebars. To adjust the gear mechanism, you will have to pedal the bike while you work.
Step 2. Shift the bike to the highest gear possible
This will be the smallest sprocket in the rear cassette system. It will be the one furthest from the bike. A gear mechanism works by tension in the cable, and the highest speed is the point of least tension, which means that the gear will do the least work and therefore will be easier to adjust.
Pedal the bike and locate the cable that leads to the rear derailleur, then carefully pull it out. See how it changes the bike for you! All a gear mechanism does is adjust the tension of the cable
Step 3. Locate the tension regulator, then follow this cable around the bike to see if it presents any problems
The tension regulator is the small cylinder that connects the cable to the gear mechanism. Follow the rear derailleur cable to the handlebars. The tension in this cable is what generates the speed change. Make sure it is attached to your cover and that it is not bent, loose, or caught in something. This problem is rare, but it does happen.
Step 4. Try to shift at all gears in both directions, and identify any problems
Keep pedaling the bike and changing gears one at a time. Memorize the times when the chain misses a sprocket or you have to make two shifts for a sprocket to pass. Is the bike having trouble getting on or off? Does it make any noise or friction?
Step 5. Return to the highest gear and begin to change gears until you reach a “problem area”, as mentioned
For example, if your bike is having trouble going from fourth to fifth gear, stop shifting when you reach fourth gear. Keep pedaling and turn the tension regulator in the direction you need the cable to drop, in this case it would be counterclockwise. As you tighten the tension regulator, the tension in the cable will change, which in turn will determine how fast you are.
Note that if the bike is turned upside down, you will need to turn the adjuster away from the direction you want the chain to move
Step 6. Turn the tension adjuster counterclockwise to help the chain shift at a slower speed toward the larger sprockets
Releasing the tension adjuster will tension the cable, making it easier to pull it towards the larger sprockets. If you downshift and nothing happens, stay at the gear you shifted at and keep turning the pedals. Turn the tension adjuster clockwise until the chain lifts up and changes speed on its own; your bike will be tight.
Step 7. Turn the tension adjuster clockwise to help the chain shift at a higher speed, toward the smaller sprockets
If your chain is having trouble pulling away from the bike, you can tighten the adjuster. If you don't change gears when shifting, keep pedaling and turn the tension dial. This will decrease the tension on the gearshift, allowing the chain to “drop” smoothly onto the smaller sprockets. Keep turning slowly until the chain changes speed on its own and matches the speed at which you tried to change.
Loosening the adjuster will help if the chain jumps two sprockets at a time when going to the larger sprockets
Step 8. Check all gears by shifting up and down slowly
When you have set a gear to shift smoothly, the rest of the gear mechanism will generally work correctly. Check all the speeds to make sure you have adjusted the bike, then continue. If you're still having trouble, do the following:
- Turn the tension regulator 2 or 3 times to the right to loosen it completely, then start over. If the cable was too tight at the start, you may have to readjust it from scratch.
- Check to see if the gearshift arms or pinions are bent. If this didn't work, the bike is probably having a bigger problem.
Step 9. Lubricate the bolts and pivot points with bicycle oil to avoid further problems
Keep the chain lubricated with a special chain lubricant, this will ensure that the rigid links of the chain do not affect the changes, and that the transmission lasts a long time.
Method 2 of 2: Fix Slipping Chains
Step 1. Only tighten the limit bolts if the chain comes off on either side of the gearshift
The two screws marked "L" and "H" are used to adjust your limits. These basically determine how far the chain will be able to travel in any direction. Unless you're having trouble with the chain coming off, there is no reason to tighten these bolts on the rear derailleur (as they were likely set properly at the factory). However, you may need to adjust these bolts if you or someone else has had an accident on your bike or installed a new gear mechanism.
- If the chain keeps slipping, check your limit bolts.
- If you can't shift to the highest or lowest gear, check the limit bolts.
- If your chain rubs against the frame, check the limit bolts.
Step 2. Turn the “H” (high) limit screw clockwise to prevent the chain from traveling too far to the right, away from the bike
Obviously, you would have to turn it counterclockwise if the chain stops too soon. Limit H is for the smallest sprocket on the rear derailleur.
Step 3. Turn the “L” (low) limit screw clockwise to prevent the chain from shifting too far to the left (and perhaps towards your rim)
Again, turn it in the opposite direction (counterclockwise) if the limit is too far in. On the rear derailleur, the L limit is used for the largest sprocket.
Step 4. Shift into high and low gears, and note that the gearshift is aligned with the center of the sprockets
When you have the boundaries where you want them, make sure they are well aligned. The sheave (metal arm with small sprockets located under the gearshift) should be aligned just below the chain.
Step 5. Test both screws and observe when the gearshift moves if the H and L are no longer marked
If you are on the furthest sprocket, you will notice that the gearshift moves when you tighten the bolts. So if you need to adjust the L limit, switch to the sprocket that is far to the left, the largest. Turn both screws half a turn and see if the gearshift comes to move. Make sure it is aligned to the center of the gear, then turn both screws back a half turn so you don't screw up the limits of the correct screw.
Advice
- Adjustments should be made gradually.
- Always make sure that the gear hanger (where the gear joins the frame) is not bent, as it will need to be straightened before attempting to adjust the gear.
- The process for adjusting the front gearshift is almost identical.
Warnings
- If you don't adjust the rear derailleur properly, the chain could come off, damaging the frame and sending the gear towards the rear tire.
- You could have a hard time doing this if you don't have a bike repair experience. If you're not sure if you can, go to your nearest favorite bike shop and see if a store clerk can show you how to adjust the mechanism.