how to adjust rear derailleur on mountain bike

How to Adjust the Rear Derailleur on a Mountain Bike

Adjusting the rear derailleur on your mountain bike is a crucial skill for any rider. Proper adjustment ensures smooth gear shifting, enhances performance, and prolongs the life of your drivetrain components. Whether you’re tackling steep trails or cruising through flat terrain, a well-tuned derailleur can make all the difference. Here’s a comprehensive guide on how to adjust the rear derailleur of your mountain bike.

Understanding the Rear Derailleur

The rear derailleur is a component of the bike's shifting system, responsible for moving the chain between different gears on the rear cassette. It consists of two main parts the body, which pivots to shift the chain, and the jockey wheels that guide the chain. The derailleur is adjusted through a combination of limit screws, cable tension, and indexing.

Tools You’ll Need

Before you start, gather the following tools - A Phillips or flathead screwdriver (depending on your derailleur model) - A 5mm Allen wrench (for cable adjustments) - A bike stand (optional, but helpful) - A chain checker (optional, for assessing wear)

Step 1 Prepare Your Bike

If possible, mount your bike on a stand. This makes adjustments easier and allows you to spin the pedals freely. Shift the bike into the smallest chainring at the front and the smallest cog at the rear. This configuration relieves tension on the derailleur and makes it easier to adjust.

Step 2 Set the Limit Screws

The limit screws control how far the derailleur can move in both the high and low settings. There are usually two screws marked “H” (high) and “L” (low).

1. Adjust the High Limit Screw Shift to the smallest rear cog. The derailleur should be aligned with the cog, and the chain should not rub against the derailleur. If it does, turn the H screw clockwise to move the derailleur closer to the cog or counterclockwise to move it away.

2. Adjust the Low Limit Screw Shift to the largest rear cog. The derailleur should not cross over to the spokes. Adjust the L screw, ensuring the derailleur is aligned with the cog and the chain runs smoothly without interference.

Step 3 Cable Tension Adjustment

Proper cable tension is critical for accurate shifting. If the derailleur shifts slowly, or if it doesn’t shift at all, you may need to adjust the cable tension.

1. To Increase Tension If the bike fails to shift up to a larger cog smoothly, turn the barrel adjuster (located where the cable enters the derailleur) counterclockwise. This increases tension.

2. To Decrease Tension If the chain struggles to shift down to a smaller cog, turn the barrel adjuster clockwise to reduce tension.

Step 4 Indexing the Gears

Once cable tension is set, it's time to fine-tune the indexing. This refers to the precise alignment of the derailleur with the cogs.

1. Start by shifting through all the gears. 2. Listen for any skipping or a delayed response. Adjust the barrel adjuster slightly (1/4 turn at a time) until each gear shifts smoothly without skipping.

Step 5 Test Ride

After completing the adjustments, take your bike for a test ride. Shift through all the gears to ensure everything is functioning smoothly. Pay attention to any unusual noises and make additional adjustments if necessary.

Conclusion

Regularly adjusting your rear derailleur not only enhances your riding experience but also extends the life of your bike components. While this process might seem daunting at first, with practice, it will become an intuitive part of your bike maintenance routine. Remember, a well-adjusted derailleur means better shifting, which ultimately leads to a more enjoyable mountain biking experience. Happy riding!