Is the Bomber CR Trunnion the Best Rear Shock for Mountain Bikes?

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The Bomber CR Trunnion [paid link] by Marzocchi has garnered significant attention from mountain bikers for its performance and durability. This rear shock is designed to provide riders with exceptional performance on rough trails, ensuring better control and comfort. In this article, we will explore the installation, maintenance, troubleshooting, and performance optimization of the Bomber CR Trunnion [paid link]. Additionally, we will discuss its compatibility with other drivetrain components and compare it with similar models to help riders make informed decisions.

Installation of the Bomber CR Trunnion

Installing the Bomber CR Trunnion on your mountain bike requires precision and care to ensure optimal performance. Below are the detailed steps to properly install the rear shock:

  1. Preparation:
    • Ensure the bike is securely mounted on a repair stand.
    • Clean the frame area where the shock will be mounted to avoid contamination during installation.
  2. Removing the Old Shock:
    • Using a 5mm Allen wrench [paid link], remove the bolts securing the old shock to the frame.
    • Gently remove the shock from its mount, taking care not to damage the suspension linkage.
  3. Installing the Bomber CR Trunnion:
    • Align the Bomber CR Trunnion with the frame’s shock mounts, ensuring the trunnion mount is correctly positioned.
    • Secure the shock with the appropriate bolts using a torque wrench [paid link], tightening to the manufacturer’s recommended torque specification.
  4. Checking Alignment:
    • Ensure that the shock is properly aligned with the suspension linkage.
    • Double-check that the mount bolts are secure and that there is no play in the shock.
  5. Final Inspection:
    • Inspect the shock and surrounding areas for any potential issues.
    • Confirm that the shock operates smoothly without any obstruction.

Adjustment and Tuning of the Bomber CR Trunnion

Adjusting the Bomber CR Trunnion is crucial for maximizing performance. Below are the key adjustments that can be made:

Rebound Adjustment

Rebound damping controls how quickly the shock returns to its original position after compression. This adjustment is essential for ensuring a smooth and controlled ride.

  • Turn the rebound knob clockwise to slow the rebound and counterclockwise to speed it up.
  • The ideal setting depends on riding conditions. If you frequently ride on rough terrain, a slower rebound will prevent the shock from “bouncing” too much.

Compression Adjustment

Compression damping controls how the shock reacts when it compresses under impact.

  • Adjust the low-speed compression knob to increase or decrease resistance when the shock compresses.
  • Higher compression settings are ideal for smoother trails, while lower settings provide more responsiveness on technical terrain.

Air Pressure

Air pressure in the Bomber CR Trunnion is vital for the shock’s overall performance. It directly impacts the shock’s sag and responsiveness.

  • To adjust the air pressure, use a high-quality shock pump.
  • The ideal pressure is typically based on your weight and riding style. Refer to the manufacturer’s guidelines for specific pressure recommendations.

Maintenance of the Bomber CR Trunnion

Routine maintenance ensures the longevity and performance of your Bomber CR Trunnion. Below are essential maintenance tasks:

Regular Cleaning

  • After each ride, clean the shock with mild soap and water to remove dirt and debris. Avoid using harsh chemicals that can damage the shock’s seals.

Lubricating the Seals

  • Periodically lubricate the seals with a silicone-based lubricant. This prevents drying and helps maintain a smooth stroke.

Checking for Leaks

  • Inspect the shock for any signs of oil leakage, particularly around the seals and the air valve. Leaks can indicate damaged seals that need replacement.

Service Intervals

  • Marzocchi recommends servicing the Bomber CR Trunnion every 50 hours of riding or annually, whichever comes first. During a full service, the shock will be disassembled, cleaned, and reassembled with fresh oil and lubricants.

Troubleshooting Common Issues

While the Bomber CR Trunnion is a reliable and durable shock, riders may occasionally encounter issues. Here are some common problems and their solutions:

Lack of Rebound Control

  • Cause: The rebound knob may be incorrectly adjusted, or the shock could have an internal issue.
  • Solution: Check the rebound settings and adjust accordingly. If the issue persists, it may be necessary to send the shock in for a service.

Bottoming Out

  • Cause: This occurs when the shock does not have enough compression damping or air pressure.
  • Solution: Increase the air pressure or adjust the compression settings to prevent bottoming out. Check for any damage or wear on the shock.

Noisy Shock

  • Cause: A noisy shock can be caused by dirt in the damper, lack of lubrication, or worn seals.
  • Solution: Clean and lubricate the shock, paying special attention to the seals. If the noise persists, it might be time for a full service.

Customization and Optimization for Performance

To achieve the best performance from the Bomber CR Trunnion, riders can make several customizations:

Adjusting Sag

  • Sag refers to how much the shock compresses under the rider’s weight. The ideal sag is typically around 25-30% of the shock’s total travel.
  • To adjust sag, fine-tune the air pressure to achieve the desired compression.

Fine-Tuning Compression and Rebound

  • Adjust both compression and rebound settings to match the type of terrain you ride. Softer settings are ideal for technical trails, while firmer settings provide more stability on smooth trails.

Upgrading the Spring

  • While the Bomber CR Trunnion comes with an air spring, riders can opt for a coil spring for a smoother, more consistent feel on rough terrain. This upgrade can enhance performance, especially for riders who prefer a more linear shock curve.

Compatibility with Other Drivetrain Components

The Bomber CR Trunnion is compatible with most modern mountain bike suspension systems. However, compatibility with other drivetrain components, such as the frame and linkage, is essential for optimal performance.

  • Frame Compatibility: Ensure that your bike frame is designed to accommodate a trunnion-style rear shock. Most modern frames support this type of shock, but it is always advisable to check the specifications before purchasing.
  • Drivetrain Integration: The rear shock’s performance can be affected by the geometry of the frame and the linkage design. Ensure that the suspension system works harmoniously with the drivetrain for smooth, responsive rides.

Comparison with Similar Models

When considering the Bomber CR Trunnion, it’s useful to compare it with similar rear shocks on the market. Below is a comparison with two other popular rear shocks in the same category.

Fox Float X2

  • Pros: The Fox Float X2 offers excellent adjustability and a highly refined damping system, providing a plush feel on rough terrain.
  • Cons: It is generally more expensive than the Bomber CR Trunnion and can be more complex to tune.

RockShox Super Deluxe Coil

  • Pros: The RockShox Super Deluxe Coil offers superb performance on downhill trails, with a more linear feel compared to the Bomber CR Trunnion’s air spring.
  • Cons: The coil shock is heavier, and riders looking for lighter setups might find it less desirable.

Bomber CR Trunnion vs Competitors

  • The Bomber CR Trunnion stands out for its affordability and reliable performance. It provides a great balance between quality and cost, especially for riders looking for a well-rounded shock that performs on varied terrains. While the Fox Float X2 and RockShox Super Deluxe Coil may offer more refined performance, the Bomber CR Trunnion delivers excellent value for riders on a budget.

Conclusion

The Bomber CR Trunnion by Marzocchi is an excellent rear shock that combines reliability, adjustability, and affordability. Its easy installation, effective adjustment features, and durability make it an ideal choice for mountain bikers looking for a high-performance shock. With proper maintenance and the right tuning, the Bomber CR Trunnion can elevate your riding experience, especially for those who need a balance of performance and value. Whether you are a seasoned rider or a beginner, this shock is a solid choice for your mountain bike.