DIY Rear Derailleur Adjustment for RED eTap (11-speed) on Gravel Bikes

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The SRAM RED eTap (11-speed) is a high-performance electronic shifting system designed for smooth and precise shifting. Its wireless design eliminates the hassle of cables and makes for a cleaner bike setup, particularly on gravel bikes where durability and shifting reliability are essential. This guide will provide step-by-step instructions on how to adjust the rear derailleur of your RED eTap system to ensure optimal performance on your gravel bike.

Tools Required

  • 4mm and 5mm Allen wrenches [paid link]
  • Torque wrench
  • Phillips head screwdriver
  • Bike stand
  • Battery charger (for RED eTap components)
  • Tape measure or ruler
  • Work gloves (optional)

Rear Derailleur Overview

The RED eTap rear derailleur uses an electronic motor to move the derailleur, controlled by the shift buttons on the handlebars. Unlike mechanical systems, this setup does not require any cables, which can stretch or wear over time. The system operates with a precise and reliable wireless signal, making it highly accurate and easy to maintain. Understanding the setup and configuration of the derailleur is essential for performing adjustments correctly.

Installation of the RED eTap Rear Derailleur

Before adjusting the derailleur, ensure that it is properly installed on your gravel bike. The installation process includes mounting the derailleur hanger, aligning the derailleur, and securing it with the necessary bolts.

  1. Mount the Derailleur
    Attach the derailleur to the derailleur hanger on the frame using a 5mm Allen wrench. Tighten the bolt securely but avoid overtightening.
  2. Position the Battery
    The battery needs to be properly installed in the derailleur. Clip the battery into the mounting bracket located on the rear derailleur. Make sure it is secured, ensuring no loose connections that could interrupt shifting performance.
  3. Check Alignment
    Ensure that the derailleur is aligned with the cassette. If misaligned, it can cause shifting problems, so adjust the hanger accordingly. Use a derailleur hanger alignment tool if necessary to ensure the hanger is straight.
  4. Cable-Free Setup
    The RED eTap system operates wirelessly, so no cables need to be run through the frame. Confirm that the electronic connections between the shifters and the derailleur are functioning properly by checking the battery status and ensuring that the signals are syncing.

Adjusting the Rear Derailleur

Once the derailleur is properly installed, follow these steps to adjust the rear derailleur for optimal shifting performance.

1. Adjust the B-Tension

The B-tension screw adjusts the distance between the derailleur’s jockey wheels and the cassette. This is crucial for smooth shifting, especially on gravel bikes where riding conditions can vary.

  • Use a 5mm Allen wrench to adjust the B-tension screw.
  • Shift to the smallest cog and inspect the derailleur.
  • The jockey wheels should be aligned just above the teeth of the smallest cog, but not too close. If the jockey wheel is too far from the cassette, adjust the screw to bring it closer; if too close, adjust it to create more clearance.

2. Set the Limit Screws

The limit screws control the range of motion of the derailleur and prevent it from shifting beyond the cassette’s largest and smallest cogs.

  • High Limit Screw (H-screw): Adjust this screw when the derailleur is not shifting to the highest (smallest) cog.
    • Shift to the smallest cog and inspect the derailleur. If the derailleur is trying to overshoot the cog, adjust the H-screw to limit the derailleur’s travel.
  • Low Limit Screw (L-screw): This screw limits the derailleur’s movement on the largest cog.
    • Shift to the largest cog and ensure that the derailleur doesn’t overshoot or miss the cog. If it does, adjust the L-screw until it moves smoothly to the largest cog.

3. Fine-tuning the Electronic Shifting

Since the RED eTap uses electronic signals, fine-tuning the shifting involves ensuring the system is calibrated correctly.

  • Press and hold the shift button until the derailleur moves to the desired cog.
  • If the derailleur doesn’t shift precisely or hesitates, the electronic system may need recalibration. This can be done via the SRAM AXS app, which allows you to adjust settings and perform diagnostics on your system.
  • Follow the prompts in the app to recalibrate if necessary. Ensure that both the front and rear derailleurs are properly synced.

4. Chain Length and Position

A correctly sized chain is vital for proper shifting across all gears. The RED eTap system will not shift properly if the chain is too short or too long.

  • To check the chain length, shift to the largest chainring and the largest cog.
  • Measure the length of the chain, ensuring there is no excessive slack or tension.
  • If the chain is too long, remove links using a chain tool. If it’s too short, replace it with a new chain that fits properly.

Troubleshooting Common Set-Up Issues

Even with proper installation and adjustment, you may encounter some common shifting issues with your RED eTap rear derailleur. Here are some troubleshooting tips:

1. Shifting Hesitation or Delay

  • This may occur due to weak or low battery charge. Ensure that the derailleur battery is fully charged before use.
  • Check the wireless connection between the shifters and the derailleur. If the signal is weak, try resetting the connection or ensure the batteries in the shifters are fresh.

2. Erratic Shifting

  • If the derailleur shifts erratically or jumps between gears, it could be due to incorrect limit screw settings or the derailleur being misaligned with the cassette.
  • Recheck the alignment of the derailleur hanger and adjust the limit screws accordingly.

3. Derailleur Dropping to the Smallest Cog

  • If the derailleur drops to the smallest cog on its own, this could be due to an issue with the high limit screw or the electronic calibration. Adjust the high limit screw or recalibrate the system via the AXS app.

Customizing and Optimizing Performance

To get the most out of your RED eTap system on gravel bikes, consider the following optimization tips:

1. Tuning the Shift Speed

  • Using the SRAM AXS app, you can fine-tune the shift speed for quicker or slower shifts, depending on your riding preferences. For gravel riding, many riders prefer slightly slower shifts to ensure smoother transitions when riding over uneven terrain.

2. Adjusting the Jockey Wheel Tension

  • The tension of the jockey wheels can also impact shifting performance. You can adjust the derailleur’s tension via the B-tension screw for optimal power transfer and smooth shifting, particularly when riding on gravel or off-road.

3. Switching to an 11-32t Cassette

  • Gravel riding often involves varying terrain, and an 11-32t cassette can provide a better gear range for tackling steep climbs and fast descents. Ensure compatibility with your RED eTap system by checking the range and shifting capabilities within the AXS app.

Compatibility with Other Drivetrain Components

The RED eTap (11-speed) is compatible with most 11-speed drivetrains, including SRAM’s Force, Rival, and Apex groupsets. However, it is essential to check for compatibility with your bike’s specific chainring size and cassette range before upgrading or replacing components.

  • Crankset Compatibility: The RED eTap can be paired with any 11-speed compatible crankset. For optimal gravel performance, consider pairing it with a wider gear range chainring.
  • Cassette Compatibility: The RED eTap can work with cassettes from 11-28t to 11-32t, which are common options for gravel riding. Check the compatibility with your wheel hub before installation.