how to adjust back derailleur on mountain bike

How to Adjust the Back Derailleur on a Mountain Bike

Maintaining your mountain bike is essential for optimal performance, and one of the critical components that often requires adjustment is the back derailleur. A properly adjusted derailleur ensures smooth gear shifts and enhances your riding experience. In this article, we’ll go through the steps necessary to adjust the back derailleur on your mountain bike.

Understanding the Back Derailleur

The back derailleur serves several functions. It moves the chain between the different sprockets on the cassette, allowing you to change gears. Proper alignment and tension are essential for efficient shifting. Most derailleur models have two primary limit screws – one for the highest gear (smallest cog) and one for the lowest gear (largest cog). Additionally, the derailleur must be properly tensioned to ensure the chain moves smoothly.

Tools You Will Need

Before you begin the adjustment process, you will need a few basic tools - A Phillips screwdriver or a flat-head screwdriver (depending on your derailleur) - A 5mm Allen wrench (for derailleur adjustments) - Bike lubricant - A clean rag

Step-by-Step Adjustment Process

1. Inspect the Current Setup

Begin by visually inspecting the derailleur. Ensure that it is straight and free from any dirt or debris. Check the cables for fraying and that the housing is not kinked or damaged. If the cable is worn, consider replacing it to ensure smoother operation.

2. Shift to the Smallest Cog

Using the shifters on your handlebars, shift your chain onto the smallest cog at the rear. This position will allow you to adjust the high limit screw correctly.

3. Adjust the High Limit Screw

Locate the high limit screw on the derailleur. This screw restricts how far the derailleur can move outward. If the chain does not align properly with the smallest cog, turn the high limit screw clockwise to move the derailleur closer to the cog, or counterclockwise to extend it farther away. The ideal distance is about 1-2mm between the chain and the cog.

4. Shift to the Largest Cog

Next, shift to the largest cog. In this position, you’ll adjust the low limit screw. If the chain moves off the largest cog, it could derail into the spokes, which is dangerous.

5. Adjust the Low Limit Screw

Find the low limit screw, which operates similarly to the high limit screw. Turn it clockwise to move the derailleur closer to the largest cog, and counterclockwise to move it away. Again, aim for a gap of about 1-2mm between the chain and the largest cog.

6. Check the Cable Tension

After adjusting both limit screws, it is crucial to check the cable tension. Pull the cable tight and secure it in place. If the shifters are not responsive or feel too loose, you might need to increase tension by adjusting the barrel adjuster located on the derailleur or shifter.

7. Test the Shifting

Now, it’s time to test your adjustments. Shift through all the gears while pedaling the bike. Pay close attention to how smoothly the changes occur. If you hear grinding or if the chain struggles to shift, there may still be some fine-tuning needed on the tension or limits.

8. Fine-Tuning

If necessary, make slight adjustments to the barrel adjuster. Turning it counterclockwise increases tension, while turning it clockwise decreases tension. Small adjustments can make a big difference in shifting performance.

9. Lubricate the Derailleur

Once you’re satisfied with the adjustment, use a clean rag to wipe down the derailleur and apply a small amount of bike lubricant to the moving parts. This will ensure smooth operation in the future.

Conclusion

Adjusting the back derailleur on your mountain bike may seem daunting, but with the right tools and patience, you can achieve a smooth and responsive gear-shifting experience. Regular maintenance and timely adjustments not only prolong the life of your bike's components but also enhance your overall riding experience. Now that you know how to adjust your derailleur, take the time to check it regularly and enjoy those mountain trails with confidence!