how to adjust rear derailleur mountain bike

How to Adjust the Rear Derailleur on a Mountain Bike

Adjusting the rear derailleur of your mountain bike is an essential skill every cyclist should learn. Proper adjustment ensures smooth shifting, prolongs the life of your drivetrain components, and enhances your overall riding experience. This guide will walk you through the process of adjusting your rear derailleur, step by step.

Understanding the Rear Derailleur

Before diving into the adjustment process, it’s essential to understand the basic parts of a rear derailleur. It consists of several components the body, the tension spring, the jockey wheels (pulleys), and the limit screws. The derailleur works by pulling the chain from one cog (gear) to another, using a mechanism that either tightens or loosens the chain tension.

Tools Needed

You'll need the following tools

- A 5mm Allen wrench - A Phillips screwdriver - A chain checker tool (optional) - Bike stand or a method to elevate the bike

Step-by-Step Adjustment

1. Check Your Shifting

Before making any adjustments, shift through all the gears, paying attention to any hesitations or misalignments. If you're having trouble shifting to the highest (smallest) gear or the lowest (largest) gear, you might need to adjust your derailleur.

2. Set the Limit Screws

The limit screws ensure the chain doesn't go beyond the large or small cog.

- Locate the limit screws There are usually two marked as “H” (high) and “L” (low) on the derailleur. - Adjust the High Limit (H) Shift to the smallest chainring and the smallest rear cog. The chain should sit right over the cog without touching it. If the derailleur moves too far towards the spokes, turn the “H” screw clockwise to tighten the limit. If the chain is not adequately positioned, turn the screw counterclockwise to adjust.

- Adjust the Low Limit (L) Shift to the largest chainring and the largest rear cog. The chain should be aligned properly without rubbing against the derailleur. If it’s not, adjust the “L” screw in the same manner as the “H” screw.

3. Adjust the Cable Tension

If you’re experiencing sluggish shifting, it might be due to insufficient cable tension.

- Locate the barrel adjuster This is usually found at the derailleur or on the shifter.

- Increase cable tension Turn the barrel adjuster counterclockwise to tighten the cable. Test the shifting again to see if it improves. If the shifting is too quick or the chain jumps, reduce the tension by turning it clockwise.

4. Fine-Tune the B-Screw

The B-screw adjusts the distance between the derailleur and the cassette, ensuring proper clearance.

- Locate the B-screw This is usually located on the back of the derailleur.

- Adjust the clearance Shift to the largest cog, and adjust the B-screw so that there’s about 5-6mm clearance between the top pulley of the derailleur and the largest cog. Turn it clockwise to decrease the gap (more tension), or counterclockwise to increase the gap (less tension).

5. Test the Shifting

After making your adjustments, shift through all of your gears multiple times. Pay close attention to how the bike shifts under load - you want it to be smooth and precise. If necessary, go back and make minor adjustments to the limit screws or cable tension as needed.

6. Regular Maintenance

To keep your derailleur and shifting in top shape, regularly clean and lubricate the chain, inspect the derailleur for any wear or damage, and ensure the cables are not frayed.

Conclusion

Adjusting the rear derailleur on your mountain bike may seem daunting at first, but with a bit of practice, it becomes a straightforward process that can greatly enhance your riding experience. Not only will proper adjustment lead to better performance on the trails, but it will also save you money on repairs and maintenance in the long run. Happy riding!