The SRAM RED eTap AXS (12-speed) is a high-performance, wireless electronic shifting system that offers smooth, precise, and reliable shifting for gravel bike riders. As with any drivetrain system, periodic maintenance and adjustments are necessary to ensure optimal performance. This guide will walk you through the steps for adjusting the rear derailleur on your RED eTap AXS system, helping you get the most out of your gravel bike.
Tools Required
- 5mm Allen wrench
- T25 Torx wrench
- Torque wrench
- Chain checker tool
- Flathead screwdriver
- SRAM AXS App (optional for fine-tuning)
- Lubricant (for derailleur pivot points)
Understanding the RED eTap AXS Rear Derailleur
Before diving into the adjustment process, it is crucial to understand the functionality of the RED eTap AXS rear derailleur. The eTap AXS system utilizes wireless technology for shifting, eliminating the need for mechanical cables. Instead, it relies on small motors within the derailleur to move the chain between cogs, activated by shifting commands sent through the eTap buttons. The system’s adaptability to 12-speed drivetrains and gravel-specific configurations makes it an excellent choice for mixed-terrain rides.
The rear derailleur controls the movement of the chain across the cassette. It needs to be set up correctly to ensure accurate shifting and smooth performance. Over time, various factors such as chain wear, derailleur hanger alignment, and bike usage can cause the derailleur to fall out of alignment.
Steps to Adjust the Rear Derailleur
Step 1: Prepare the Bike and Tools
Before starting any adjustments, ensure that the bike is stable, preferably in a repair stand, to keep the rear wheel elevated. Gather the necessary tools, and ensure the drivetrain is clean and well-lubricated.
Step 2: Check the Battery Levels
The RED eTap AXS system is powered by batteries located in the front and rear derailleurs. Use the SRAM AXS app to check the battery levels of both derailleurs. Low batteries can cause poor shifting performance. Replace or charge the batteries if necessary.
Step 3: Inspect the Derailleur Hanger Alignment
The derailleur hanger is a critical component in ensuring the proper alignment of the rear derailleur. An misaligned hanger can cause the derailleur to shift poorly or even damage the drivetrain. To check for hanger alignment:
- Remove the rear wheel from the bike.
- Use a derailleur hanger alignment tool to ensure the hanger is straight. If it’s bent, adjust it carefully or replace it if necessary.
Step 4: Adjust the Limit Screws
Limit screws control the range of movement of the rear derailleur, preventing it from overshooting the cogs or chainring. Adjusting the limit screws is essential for precise shifting.
- High Limit Screw (H): Adjusts the derailleur’s movement toward the smallest cog.
- Low Limit Screw (L): Adjusts the derailleur’s movement toward the largest cog.
To adjust the limit screws:
- Shift the chain to the smallest cog in the rear.
- Use a T25 Torx wrench to adjust the high limit screw (H) so the derailleur is aligned just outside the smallest cog.
- Shift the chain to the largest cog in the rear.
- Adjust the low limit screw (L) so the derailleur is aligned just inside the largest cog.
Step 5: Fine-Tune the B-Screw Adjustment
The B-screw controls the position of the derailleur relative to the cassette. Proper B-screw adjustment ensures that the derailleur stays at an optimal distance from the cassette throughout the entire gear range, preventing poor shifting or chain rub.
To adjust the B-screw:
- Shift the bike into the largest cog.
- Use a flathead screwdriver to adjust the B-screw until the derailleur’s jockey wheels are about 5-6mm away from the largest cog.
Step 6: Set the Correct Chain Length
An improperly sized chain can cause skipping or inefficient shifting. To check the chain length, shift the bike to the largest chainring and the largest cog on the cassette. The chain should be long enough to shift to the largest cog without overstretching or causing the derailleur to be overstressed.
If the chain is too long:
- Shift to the largest chainring and cog.
- Use a chain tool to remove the excess links.
- Reinstall the chain and ensure it shifts properly across the entire range.
Step 7: Fine-Tune Shifting Using the AXS App
Once the mechanical adjustments are done, use the SRAM AXS App for electronic fine-tuning. The app allows you to fine-tune the derailleur’s position and shifting performance. This step is useful for making small corrections that cannot be achieved through mechanical adjustments alone.
In the AXS app:
- Select the “Adjust Rear Derailleur” function.
- Follow the on-screen instructions to make precise adjustments to the derailleur’s movement and shifting performance.
Step 8: Test the Shifting
After all adjustments are made, it’s time to test the shifting. Shift through all the gears, both up and down, ensuring smooth and precise transitions between cogs. If any gears are not shifting correctly, return to the appropriate step and make further adjustments as necessary.
Step 9: Torque the Bolts to Specification
Ensure all bolts, including those for the derailleur hanger and derailleur, are properly torqued. Use a torque wrench to tighten all bolts to the manufacturer’s recommended specifications to avoid damage or issues during riding.
Troubleshooting Common Set-up Issues
Issue 1: Poor Shifting Performance
If the shifting feels sluggish or imprecise, check the following:
- Derailleur hanger alignment: Even a small bend can impact shifting.
- Chain wear: A worn chain can cause inconsistent shifting, so check the chain with a chain checker tool and replace if necessary.
- Battery levels: Low battery levels can lead to poor shifting. Charge or replace the batteries.
Issue 2: Chain Dropping Off Cogs
If the chain drops off the cogs, ensure the limit screws are correctly adjusted. If the high or low limit is set too far, the derailleur may push the chain too far in either direction. Make sure the derailleur stays within the boundaries of the cassette cogs.
Issue 3: Skipping Gears
If the bike skips gears, the B-screw or derailleur hanger alignment may need adjustment. Ensure the B-screw is properly adjusted and that the derailleur is aligned with the cassette.
Customization and Optimization for Better Performance
To optimize the performance of your RED eTap AXS system, consider the following customization options:
- Adjusting Shifting Speed: The SRAM AXS app allows you to adjust the shifting speed to match your riding style, whether you prefer faster or slower shifts.
- Fine-tuning the Jockey Wheels: Replacing the derailleur’s jockey wheels with aftermarket options designed for gravel riding can reduce friction and improve drivetrain efficiency.
- Chain and Cassette Compatibility: Ensure that your chain and cassette are compatible with the RED eTap AXS drivetrain to prevent skipping or chain wear. The 12-speed drivetrain works best when paired with compatible components from SRAM’s AXS system.
Comparison with Other Models
When compared to other electronic drivetrains, the RED eTap AXS offers a unique combination of wireless operation and high-performance shifting. While Shimano’s Di2 system also offers electronic shifting, the RED eTap AXS system stands out due to its simplicity, ease of installation, and low maintenance. Additionally, the wireless nature of the RED eTap AXS removes the need for complicated wiring, which is a key advantage for gravel bike setups where durability and simplicity are important.
Understanding Compatibility with Other Drivetrain Components
The RED eTap AXS system is designed to be highly compatible with other SRAM AXS components. It integrates seamlessly with SRAM’s 12-speed cassettes, cranks, and chainrings. When building or upgrading your gravel bike, make sure that all drivetrain components are from the same manufacturer to ensure proper function. While it is possible to use non-SRAM components, doing so may result in shifting issues or inefficiency. Always double-check compatibility before installing or upgrading any components.
By following these steps, you can ensure your RED eTap AXS (12-speed) rear derailleur functions at its best, providing smooth, precise shifting on your gravel bike. Proper adjustments and regular maintenance will help you enjoy a more reliable and enjoyable ride on a variety of terrains.