DIY Rear Derailleur Adjustment for Apex XPLR on Gravel Bikes

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The SRAM Apex XPLR [paid link] rear derailleur is an excellent choice for gravel cyclists who demand reliable performance and precise shifting, even in rugged terrain. Properly adjusting the Apex XPLR rear derailleur ensures smooth and accurate shifting, reduces wear on the drivetrain, and improves overall riding experience. This guide will walk you through the steps required to install, adjust, and maintain your Apex XPLR derailleur for optimal performance on your gravel bike.

Tools Required

  • 5mm Allen wrench
  • 3mm Allen wrench
  • Flathead screwdriver
  • Torque wrench
  • Chain checker tool
  • 11/12-speed chain tool (if necessary)
  • Cable cutters
  • Lubricant (for cables and pivot points)
  • Tension gauge (optional for precise indexing)

Installation of the Apex XPLR Rear Derailleur

  1. Remove the Old Derailleur:
    • Start by removing the existing rear derailleur if you’re replacing it. Use a 5mm Allen wrench to detach the derailleur from the derailleur hanger.
    • Remove the chain from the derailleur using a chain tool, if required.
  2. Install the New Derailleur:
    • Position the Apex XPLR derailleur on the derailleur hanger and tighten the mounting bolt with the 5mm Allen wrench. Ensure the derailleur is aligned properly with the hanger and parallel to the frame.
  3. Attach the Chain:
    • Using a chain tool, connect the chain to the derailleur. Make sure the chain is threaded through the jockey wheels, and ensure it’s the correct length for your bike’s gearing setup.
  4. Install the Rear Shifter Cable:
    • Insert the rear shifter cable through the shifter, following the manufacturer’s instructions. Make sure the cable is routed through the appropriate cable guides and housing, keeping it free from friction.
  5. Attach the Cable to the Derailleur:
    • Feed the cable into the derailleur’s cable anchor bolt and secure it. Leave a small amount of slack to allow for proper tensioning during adjustment.
  6. Check the Derailleur Hanger Alignment:
    • Ensure the derailleur hanger is straight. A misaligned hanger can cause shifting issues. Use a derailleur hanger alignment tool to confirm it’s in the correct position.

Adjustment of the Apex XPLR Rear Derailleur

Setting the B-Screw

The B-screw adjusts the distance between the derailleur’s jockey wheels and the cassette, which is crucial for smooth shifting across the entire gear range.

  1. Shift to the Smallest Cog:
    • Use your shifter to move the chain to the smallest cog on the cassette and shift to the highest gear in the front.
  2. Adjust the B-Screw:
    • Locate the B-screw at the back of the derailleur. Turn it clockwise to decrease the gap between the jockey wheel and the cassette. Turn it counterclockwise to increase the gap.
    • The gap should be between 5–10mm for optimal performance. Fine-tune the distance as needed.

Setting the High and Low Limit Screws

These screws control the derailleur’s range of movement, preventing the chain from overshooting the cassette.

  1. Adjust the High Limit Screw:
    • Shift to the smallest cog in the rear cassette.
    • Using a 3mm Allen wrench, adjust the high-limit screw to ensure the derailleur cannot shift beyond the smallest cog.
    • The derailleur should align perfectly with the smallest cog, with no risk of the chain falling off the outer edge.
  2. Adjust the Low Limit Screw:
    • Shift to the largest cog in the rear cassette.
    • Adjust the low-limit screw to ensure the derailleur cannot shift beyond the largest cog. The derailleur should align directly with the largest cog, with no chance of the chain jumping off.

Indexing the Gears

Indexing ensures smooth shifting between cogs, and it involves adjusting the cable tension.

  1. Shift Through the Gears:
    • Shift through each gear while watching the derailleur’s movement. If the derailleur is slow to shift, or if the chain skips cogs, the cable tension needs to be adjusted.
  2. Fine-Tune Cable Tension:
    • Use the barrel adjuster located either on the derailleur or the shifter to fine-tune the cable tension. Turn it clockwise to increase tension or counterclockwise to decrease it.
    • Small adjustments at the barrel adjuster can make a significant difference, so proceed with slight turns until you achieve crisp, accurate shifting.
  3. Test the Shifting:
    • After adjusting the tension, shift through all the gears again to ensure smooth and accurate shifting. If necessary, continue fine-tuning the barrel adjuster until the chain moves cleanly between cogs.

Troubleshooting Common Issues

1. Chain Skipping or Slipping

  • Cause: This is often due to insufficient tension in the rear derailleur cable.
  • Solution: Adjust the cable tension using the barrel adjuster until the chain shifts cleanly without skipping.

2. Derailleur Hanging Too Low or High

  • Cause: The derailleur may not be properly aligned with the cassette.
  • Solution: Check the derailleur hanger alignment and adjust the high and low limit screws to ensure proper alignment.

3. Noise During Shifting

  • Cause: Misadjusted B-screw or improper cable tension.
  • Solution: Ensure the B-screw is correctly set and the cable tension is appropriate for smooth shifting. Additionally, check the jockey wheels for debris and lubricate them if needed.

Customization and Optimization

The SRAM Apex XPLR rear derailleur can be fine-tuned for better performance, especially when used in demanding gravel conditions.

Chain Length

  • Shorter Chains: A shorter chain will reduce drag and improve shifting performance, but it can limit the range of your gears. Ensure the chain is long enough to handle the largest cog.
  • Longer Chains: A longer chain offers better gear range, but may result in more chain drag, especially in the smaller cogs. Find the ideal chain length that works best for your riding style.

Upgrading to a Wider Gear Range

  • The Apex XPLR is compatible with wide-range cassettes, which are ideal for gravel riding. For better hill-climbing ability or higher speeds on flat terrain, consider upgrading to a cassette with a larger range, such as the 10-42T or 10-50T.

Compatibility with Other Drivetrain Components

The Apex XPLR rear derailleur is designed to work with SRAM’s wide-range 1×12-speed drivetrains, though it may also be compatible with other SRAM 11-speed systems, depending on the configuration. When combining the Apex XPLR derailleur with other drivetrain components, make sure to verify the compatibility of your cassette, shifter, and crankset. Mixing 11-speed and 12-speed components can result in shifting issues, so ensure all components are compatible.

Conclusion

By following these steps, you can confidently install, adjust, and maintain your SRAM Apex XPLR rear derailleur for optimal performance on gravel rides. Proper setup and tuning will ensure your drivetrain performs smoothly and efficiently, reducing maintenance costs and enhancing your overall riding experience. Regular maintenance checks, such as ensuring proper chain length and B-screw adjustment, will keep your bike in top condition and ready for any terrain.