How to Install Your RED eTap AXS (12-speed) Rear Derailleur at Home

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Installing the SRAM RED eTap AXS (12-speed) rear derailleur requires a methodical approach to ensure proper functioning and smooth shifting performance. In this guide, we will walk you through the installation process, troubleshooting tips, and optimal adjustment techniques for this high-performance derailleur.

Tools Required

  • 5mm Allen wrench
  • 2.5mm Allen wrench
  • Torque wrench
  • Chain checker
  • Phillips screwdriver
  • SRAM AXS battery
  • Rear wheel with compatible cassette
  • Chain tool (optional)
  • Cable cutters (optional)
  • Cleaning supplies (rags, degreaser)

Step 1: Prepare Your Bike

Before beginning the installation of the RED eTap AXS rear derailleur, ensure that your bike is in an upright position on a work stand. This will give you easy access to all areas of the bike and minimize the risk of damage.

  • Remove the old derailleur (if applicable).
  • Inspect your drivetrain for any excessive wear, including the chain and cassette.
  • Clean the area where the derailleur attaches to the frame, ensuring that no dirt or debris is present.

Step 2: Attach the Rear Derailleur

The RED eTap AXS rear derailleur uses a traditional derailleur hanger for mounting. Follow these steps to properly install it:

  1. Align the derailleur mounting hole with the derailleur hanger on your bike frame.
  2. Insert the mounting bolt through the derailleur’s mounting hole and tighten it using a 5mm Allen wrench.
  3. Torque the mounting bolt to the recommended specification, usually between 6-8 Nm (check the manufacturer’s specifications for exact values).

Ensure that the derailleur is aligned parallel to the bike frame to prevent any misalignment during shifting.

Step 3: Install the AXS Battery

The RED eTap AXS rear derailleur relies on a wireless system powered by a removable AXS battery. Follow these steps to install the battery:

  1. Insert the AXS battery into the derailleur’s battery compartment. The battery should click into place.
  2. Make sure the battery is securely seated and that no wires are exposed or pinched.
  3. Ensure the battery is charged, which can be checked via the AXS mobile app or the LED light indicator on the derailleur.

Step 4: Mount the Chain and Rear Wheel

With the derailleur securely attached, it is now time to reinstall the chain and rear wheel.

  1. Install the rear wheel onto the bike frame, ensuring it is properly seated in the dropouts and secured with the quick release or through-axle.
  2. Using a chain tool, remove and install the chain if necessary, ensuring that the chain size is appropriate for the 12-speed drivetrain.
  3. Route the chain through the derailleur jockey wheels, ensuring it moves freely and without binding.

Double-check the chain length by ensuring it is neither too tight nor too loose. Adjust the chain length if necessary.

Step 5: Connect the AXS Components

The RED eTap AXS system utilizes wireless communication between the rear derailleur, front derailleur (if applicable), and shifters. Connect the system by following these steps:

  1. Power on the AXS system by holding the button on the rear derailleur or shifters for several seconds until the LED flashes.
  2. Open the SRAM AXS app on your smartphone and follow the prompts to pair the rear derailleur with your shifters.
  3. Once paired, test the system by shifting through all available gears to ensure proper communication and function.

If the system does not connect, reset the AXS components and repeat the pairing process.

Step 6: Adjust the Limit Screws

With the derailleur installed and connected, fine-tuning the limit screws is crucial to avoid chain drop or excessive derailleur movement. The limit screws control the travel of the derailleur across the cassette.

  1. Shift the bike into the smallest cog on the cassette and adjust the H (high) limit screw using a 2.5mm Allen wrench. This screw ensures the derailleur does not shift too far inward.
  2. Shift into the largest cog and adjust the L (low) limit screw to prevent the derailleur from shifting off the cassette.
  3. Verify both limit screws by shifting through all gears, ensuring smooth movement across the entire range.

Test the shifting performance and ensure there is no overshooting of the derailleur in either direction.

Step 7: Fine-tune the Indexing

Now that the limit screws are adjusted, fine-tune the derailleur’s indexing to ensure smooth and precise shifting between gears.

  1. Shift the bike into the middle of the cassette.
  2. Use the fine-tuning adjuster on the derailleur or shifter to make small adjustments to the cable tension.
  3. Shift up and down through the gears to ensure smooth transitions and crisp shifting.

If the bike skips or hesitates while shifting, slightly increase or decrease the tension until the shifts are precise.

Step 8: Test the System

Before hitting the road, test the complete system thoroughly:

  1. Spin the pedals to ensure smooth shifting between gears.
  2. Shift through the full range of the cassette, making sure the chain moves freely and there is no chain rub on the derailleur cage.
  3. Test under load by pedaling while in various gears to ensure reliable performance.

Pay attention to any unusual noises, hesitation, or misalignment during shifting.

Troubleshooting Common Set-up Issues

If you’re experiencing issues with your RED eTap AXS rear derailleur after installation, consider the following troubleshooting steps:

  • Poor Shifting Performance: Check the AXS battery charge level and ensure the derailleur is properly paired with the shifters. Re-adjust the limit screws and indexing.
  • Chain Drop or Misalignment: Recheck the derailleur alignment and ensure that the derailleur hanger is not bent.
  • Wireless Connection Problems: Ensure that the AXS components are within range and that no interference is affecting the wireless signal. Reset the system if necessary.

Customization and Optimization for Better Performance

To get the most out of your RED eTap AXS rear derailleur, consider these customization tips:

  1. Adjust the derailleur cage length: If you’re using a large cassette (e.g., 11-32T or 10-36T), opt for a long cage to ensure smooth shifting and prevent chain slack.
  2. Upgrade the chain: Consider upgrading to a high-performance chain for smoother shifting and longer lifespan.
  3. Optimize battery placement: Ensure the AXS battery is securely mounted and positioned for easy access during charging.

Compatibility with Other Drivetrain Components

The SRAM RED eTap AXS rear derailleur is compatible with other AXS components, including the front derailleur and shifters, as well as SRAM’s wide range of 12-speed cassettes. However, it is important to ensure that all components are designed for 12-speed drivetrains and that the chain length is appropriate for the selected cassette.

For optimal performance, pairing the RED eTap AXS derailleur with a compatible AXS shifter and AXS front derailleur will provide the most seamless experience, as the system has been specifically engineered to work together.