How to Install, Adjust, and Maintain the SX Rear Derailleur

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in Rear Derailleur, SRAM

The SX Rear Derailleur [paid link] is a key component in SRAM’s mountain bike drivetrain lineup, designed for reliable shifting performance at an entry-level [paid link] price point. Proper installation, adjustment, and maintenance are essential to ensure smooth operation and longevity.

This guide provides a detailed step-by-step process for setting up your SX Rear Derailleur [paid link], making necessary adjustments, and performing routine maintenance to keep it running optimally.

Tools Required [paid links]

To complete this installation and adjustment process, you will need the following tools:

Step 1: Installing the SX Rear Derailleur

Before adjusting your SX Rear Derailleur [paid link], it must be installed correctly on your bike frame.

  1. Attach the Derailleur to the Hanger
    • Locate the derailleur hanger on your bike frame.
    • Align the B-tension tab with the notch on the hanger.
    • Use a 5mm Allen wrench [paid link] to tighten the derailleur mounting bolt to 8-10Nm.
  2. Install the Chain
    • If installing a new chain, use a chain breaker tool to size it correctly.
    • Route the chain through the jockey wheels and around the cassette.
    • Use a quick link or chain pin to connect the chain.
  3. Attach the Shifter Cable
    • Shift the shifter to the smallest cog (highest gear).
    • Insert the cable into the SX shifter and thread it through the derailleur.
    • Secure the cable using the cable clamp bolt and tighten to 6Nm.

At this stage, your SX Rear Derailleur is installed, and you’re ready to move on to fine-tuning adjustments.

Step 2: Setting the High and Low Limit Screws

The limit screws prevent the derailleur from shifting too far and dropping the chain.

  1. Adjust the High Limit Screw (H-Screw)
    • Shift to the smallest cog (highest gear).
    • Look at the jockey wheel alignment—it should be directly under the smallest cog.
    • If it is too far inward or outward, turn the H-screw clockwise to move the derailleur outward, or counterclockwise to move it inward.
  2. Adjust the Low Limit Screw (L-Screw)
    • Shift to the largest cog (lowest gear).
    • The jockey wheel should align with the largest cog.
    • If misaligned, turn the L-screw clockwise to move the derailleur inward, or counterclockwise to move it outward.

Step 3: Setting B-Tension for Optimal Chain Gap

The B-tension screw controls the derailleur’s distance from the cassette, affecting shifting smoothness.

  1. Shift to the largest cog.
  2. Locate the B-tension screw at the derailleur’s upper section.
  3. Adjust the screw until there is a gap of 5-6mm between the upper jockey wheel and the largest cog.

A properly set B-tension ensures crisp shifting across all gears.

Step 4: Indexing and Fine-Tuning Cable Tension

Cable tension plays a crucial role in achieving accurate shifts. Follow these steps:

  1. Shift to the second-smallest cog.
  2. Turn the barrel adjuster (located at the shifter) counterclockwise if the derailleur hesitates when shifting to a larger cog.
  3. Turn the barrel adjuster clockwise if shifting to a smaller cog is slow or hesitant.

Shift through all gears to ensure smooth transitions without hesitation or skipping.

Step 5: Maintenance and Cleaning for Longevity

Routine maintenance keeps your SX Rear Derailleur performing well for years.

Cleaning Your Derailleur

  • Use a degreaser to remove dirt and grime from the jockey wheels and derailleur body.
  • Wipe down with a clean rag and let it dry.

Lubricating Moving Parts

  • Apply a small amount of chain lubricant to the jockey wheels and pivot points.
  • Avoid over-lubricating, as excess lube can attract dirt.

Checking for Wear and Damage

  • Inspect the derailleur for bent jockey wheels, frayed cables, or misalignment.
  • Replace worn-out components as needed to maintain precise shifting.

Troubleshooting Common Issues

Issue 1: Slow or Hesitant Shifting

  • Adjust cable tension via the barrel adjuster.
  • Check for excessive dirt or corrosion on the derailleur.

Issue 2: Chain Skipping on Certain Gears

  • Verify limit screw settings.
  • Inspect the chain and cassette for wear.

Issue 3: Noisy Shifting

  • Ensure the B-tension is correctly set.
  • Clean and lubricate jockey wheels.

Conclusion

Installing, adjusting, and maintaining your SX Rear Derailleur properly is crucial for smooth, reliable shifting. By following this step-by-step guide, you can ensure your derailleur operates efficiently and lasts for years. Regular cleaning, lubrication, and fine-tuning will help keep your drivetrain in peak condition.