DIY Rear Shock Tuning: Get the Most from Your Bomber CR Trunnion

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The Marzocchi Bomber CR Trunnion [paid link] rear shock is known for its superior performance and durability, making it a top choice for riders who demand a reliable, high-performing rear suspension system. However, to ensure it delivers optimal performance, proper tuning, maintenance, and adjustments are essential. In this guide, we will walk through the process of setting up your Bomber CR Trunnion [paid link], including installation, adjustment, maintenance, troubleshooting, and how to get the best performance out of your shock.

Tools Required

  • Shock pump
  • Torque wrench [paid link]
  • 5mm and 8mm hex wrenches
  • Flathead screwdriver
  • Shock grease
  • Cleaning supplies (rags, mild soap, water)
  • Isopropyl alcohol (for degreasing)
  • Suspension fluid (Marzocchi-specific, if necessary)
  • Safety glasses and gloves

Installation of the Bomber CR Trunnion

The installation of the Bomber CR Trunnion rear shock requires precision to ensure both safety and performance. Follow these steps to install the shock correctly:

  1. Prepare the Frame: Clean the rear suspension area of your bike to avoid dirt and debris from contaminating the shock mount or internal components.
  2. Apply Grease: Apply a small amount of suspension-specific grease to the shock’s mounting hardware to ensure a smooth connection and reduce wear.
  3. Mount the Shock: Slide the Bomber CR Trunnion shock into the frame’s rear shock mount. Ensure that the shock’s eyelet is properly aligned with the frame’s mount.
  4. Tighten the Bolts: Use a torque wrench [paid link] to tighten the mounting bolts to the manufacturer’s recommended torque setting. This ensures proper installation without over-tightening.
  5. Check for Free Movement: Before proceeding, check that the shock moves freely with no interference from the frame or surrounding components.

Adjusting the Bomber CR Trunnion

Once installed, it is essential to adjust the Bomber CR Trunnion rear shock to suit your riding style and terrain. The shock features various tuning options to help you fine-tune its performance.

Air Pressure Adjustment

The air pressure in your rear shock plays a critical role in how the bike handles. The Bomber CR Trunnion comes with a built-in air chamber that can be adjusted to match your weight, riding style, and terrain conditions.

  • Determine the correct air pressure: The correct pressure depends on rider weight and intended use. Use a shock pump to add air pressure to the shock, following the recommended guidelines in the user manual. As a starting point, a common pressure range for an average rider is between 200-250 psi.
  • Fine-tune the pressure: For more aggressive riders or those tackling rough terrain, you may need to add more pressure. Conversely, for smoother rides, lower pressures provide better compliance.

Rebound Adjustment

The rebound controls how quickly the shock returns to its normal position after being compressed. Adjusting rebound is important to ensure the shock responds quickly enough to maintain control while not being too fast or slow.

  • Adjust the rebound knob: Turn the rebound knob clockwise to slow down the return or counterclockwise to speed it up. Make small adjustments to feel the difference in performance.
  • Test the rebound: After making the adjustment, perform a small bounce test. If the shock rebounds too quickly, it could cause instability, while too slow of a rebound will cause sluggish handling.

Compression Damping Adjustment

The compression damping controls the rate at which the shock compresses when riding over obstacles. Adjusting this setting is crucial for ensuring a balance between comfort and performance.

  • Adjust low-speed compression: The low-speed compression setting is ideal for smaller, slower bumps like trail chatter. Adjust this by turning the compression knob. More compression provides a firmer ride, while less compression offers more comfort.
  • High-speed compression: This adjustment controls how the shock handles faster impacts like drops and larger hits. Set the high-speed compression by turning the relevant knob on the shock.

Maintenance and Care for the Bomber CR Trunnion

Proper maintenance is essential for keeping your Bomber CR Trunnion rear shock performing at its best.

Regular Cleaning

After each ride, especially in muddy or wet conditions, it’s important to clean the shock to prevent debris buildup, which could affect performance.

  • Use a damp rag to wipe the shock clean.
  • Avoid using harsh chemicals or solvents on the shock, as they can degrade seals and lubricants.
  • Clean around the eyelets and the mounting points to ensure no dirt enters the shock.

Inspect for Leaks

Over time, seals can degrade, leading to air or oil leaks. Regularly check for any oil drips or air loss, as these could be signs that the shock needs servicing.

  • Inspect the shock for oil stains or air leakage around the seals.
  • If any leaks are found, the shock may need to be serviced by a professional or repaired using a rebuild kit.

Periodic Servicing

Even though the Bomber CR Trunnion is a robust rear shock, periodic servicing is essential to ensure optimal performance, especially after prolonged use or riding in extreme conditions. It’s recommended to have the shock serviced once a year or after every 50-100 hours of riding.

  • The service typically includes an oil change, seal replacement, and full inspection of the shock’s internals.

Troubleshooting Common Issues with the Bomber CR Trunnion

Despite its durability, you may encounter a few issues with the Bomber CR Trunnion rear shock. Here are some common problems and their solutions.

Loss of Air Pressure

  • Symptoms: The shock feels excessively soft, or the bike bottoms out more frequently.
  • Cause: This is typically due to air leakage.
  • Solution: Check for leaks around the air valve or seals. If you find a leak, inspect the shock’s seals and replace them if necessary. If the air valve is damaged, it may need to be replaced.

No Rebound or Excessive Rebound

  • Symptoms: The shock either doesn’t return to its normal position or rebounds too quickly.
  • Cause: This could be due to improper rebound settings or a malfunctioning damper.
  • Solution: Start by adjusting the rebound setting. If the problem persists, the damper might need servicing or replacement.

Lack of Compression Dampening

  • Symptoms: The shock feels excessively soft, even at higher pressures, or you experience a “spongy” feel when riding.
  • Cause: This could be due to worn-out compression dampers or seals.
  • Solution: Check the compression adjustment and clean the shock to ensure no debris is obstructing the damper. If the issue continues, consider a full rebuild.

Customization and Optimization

To get the most out of your Bomber CR Trunnion rear shock, customization and optimization are key. The ideal setup depends on factors such as riding style, terrain, and personal preference. Here are some tips for tuning your shock to suit your needs.

  • Fine-tune air pressure based on terrain and riding style. For aggressive riding or rough trails, increase pressure to prevent bottoming out. For smoother trails, lower pressure for better traction and comfort.
  • Adjust rebound and compression settings to match the type of terrain you’re riding. Softer settings work best for smoother trails, while firmer settings provide better support for more challenging terrain.
  • Experiment with settings: Don’t be afraid to adjust the shock’s settings during different rides to fine-tune your setup. What works for one trail might not be ideal for another, so it’s important to adapt.

Compatibility with Other Drivetrain Components

When setting up the Bomber CR Trunnion rear shock, it’s essential to consider how it interacts with the other components of your bike, such as the drivetrain and wheels.

  • Frame compatibility: Ensure that your bike frame is compatible with the Bomber CR Trunnion’s trunnion mount configuration. The shock’s eyelet measurement should align with the frame’s specifications.
  • Wheel size and suspension travel: The shock is best paired with frames and wheels designed for aggressive trail riding, with appropriate suspension travel to match the shock’s capabilities.
  • Drivetrain alignment: Adjusting your suspension settings might affect how the rear triangle moves, so ensure your drivetrain components (e.g., derailleur, chain) are properly aligned to avoid interference.

Conclusion

The Marzocchi Bomber CR Trunnion rear shock is a high-performance component that can significantly enhance your riding experience when properly tuned and maintained. By following the steps for installation, adjustment, and maintenance, as well as troubleshooting common issues, you can ensure that your shock delivers peak [paid link] performance for years to come. Customizing it to your riding style and terrain, while considering compatibility with your bike’s drivetrain, will allow you to fully unlock the potential of this remarkable rear shock.