Setting up your rear shock sag is a critical step for optimizing your bike’s performance, particularly when using the Marzocchi Bomber CR Coil [paid link] rear shock. This guide provides a step-by-step process on how to achieve the ideal sag, which will improve your riding experience by ensuring that your suspension absorbs bumps effectively, keeps traction with the ground, and handles aggressive terrain with stability.

Understanding Rear Shock Sag

Sag refers to the amount a shock compresses under the rider’s weight when they are on the bike. Correct sag ensures the suspension is responsive and provides the necessary comfort, control, and efficiency during rides. For the Bomber CR Coil [paid link], the correct sag will maximize the shock’s performance and prevent bottoming out or excessive bobbing, which can lead to poor bike handling.

Tools Required

• Shock pump (compatible with Marzocchi Bomber CR Coil)
• Ruler or tape measure
• Helper (optional)
• Marker or tape (to mark the shock’s shaft)

Setting Up Your Bomber CR Coil Rear Shock Sag

Follow these steps carefully to set up your Bomber CR Coil rear shock sag accurately:

Step 1: Determine Your Desired Sag Range

For most riders, the recommended sag range for the Bomber CR Coil rear shock is between 25% and 30% of the shock’s total travel. This means that for every 100mm of shock travel, you want approximately 25-30mm of sag. Adjust this range based on personal preferences, riding style, and terrain.

Step 2: Prepare Your Bike and Shock

Before setting the sag, ensure the bike is on a level surface. Remove any extra gear that you might carry (such as a backpack) since it can affect the sag. If possible, have a second person assist you in holding the bike steady while you measure.

Step 3: Measure the Shock’s Total Stroke

Using a ruler or tape measure, measure the shock’s total travel (the distance the shock can compress from fully extended to fully compressed). This can usually be found in the shock’s specifications. For example, if your Bomber CR Coil has 200mm of total travel, you will want to aim for 50-60mm of sag for the recommended 25-30%.

Step 4: Set Your Sag

1. Mount your bike and get into your normal riding position.
2. With the shock fully extended, mark the shock’s shaft with tape or a marker at the point where it meets the shock body. This marks the position of the shock in its fully extended state.
3. Slowly sit on the bike, allowing your weight to compress the shock. Try to stay as still as possible to avoid additional movement.
4. Have a helper (or do it yourself) measure the amount of compression in the shock. The distance between the fully extended mark and the new mark after compression is your sag.
5. If the sag is within your desired range (25-30% of total travel), you are all set. If not, proceed to adjust the coil spring preload.

Step 5: Adjusting the Coil Spring Preload

If the sag measurement is too low (less than 25% of total travel), increase the preload by tightening the coil spring. If the sag is too high (greater than 30% of total travel), reduce the preload by loosening the coil spring.

• To increase preload: Using the appropriate tools, turn the preload adjuster clockwise to compress the spring slightly. This will raise the rider’s weight threshold needed to compress the shock further.
• To decrease preload: Turn the preload adjuster counterclockwise to reduce the compression of the spring. This will allow the shock to sag more under your weight.

Repeat the sag measurement steps after each adjustment until the sag is in your desired range.

Testing the Setup

After you have set the sag, take the bike for a short test ride on various terrain. Pay attention to how the bike feels during climbs, descents, and rough patches. You should feel that the rear shock is responsive, not too stiff or too soft. If the bike feels unbalanced or the shock is bottoming out too easily, further adjustments may be needed.

Troubleshooting Common Setup Issues

1. Shock Bottoming Out

If the shock bottoming out is an issue, it could be a sign that you have too little sag. Increase the preload on the coil spring or consider using a softer spring rate to ensure the shock has the proper amount of sag.

2. Excessive Bobbing

Excessive rear-end bobbing during pedaling may indicate too much sag. In this case, decrease the preload slightly to reduce the amount of shock compression while pedaling, thus minimizing bobbing.

3. Uneven Sag

If the sag is uneven between the two sides of the shock, this could indicate an issue with the coil or installation. Double-check the shock mounting and alignment to ensure it is seated correctly in the bike frame.

Customization and Optimization for Better Performance

Once you have the correct sag setup, you can further customize the Bomber CR Coil for optimal performance based on your riding style:

1. Spring Rate: Choose a spring rate that matches your weight and riding style. Marzocchi offers different coil spring options, so switching out your current spring for one that matches your weight more closely can improve the shock’s performance.
2. Rebound Damping: Adjust the rebound damping to control how quickly the shock returns to its original position after compression. Slower rebound can help prevent the shock from bouncing back too quickly, especially on technical descents.
3. Compression Damping: Experiment with the compression damping settings for better control over how the shock compresses under impacts. Finer adjustments will help you balance comfort and performance on various terrains.

Comparison with Similar Models

When comparing the Marzocchi Bomber CR Coil with other coil shocks in its category, such as the Fox DHX2 or RockShox Super Deluxe Coil, there are key differences to note:

• Price: The Bomber CR Coil is generally more affordable compared to some high-end coil shocks like the Fox DHX2, making it an attractive option for riders who need a high-performance shock without breaking the bank.
• Adjustability: The Bomber CR Coil provides ample adjustability, though it may lack some of the advanced tuning features found in pricier models like the DHX2, which offers more fine-tuned adjustments for experienced riders.
• Durability: The Bomber CR Coil has a reputation for durability and can withstand heavy use and rough conditions, similar to its competitors.

Compatibility with Other Drivetrain Components

The Bomber CR Coil rear shock is compatible with a wide range of modern mountain bikes, including those designed with an emphasis on downhill and aggressive trail riding. When selecting other drivetrain components, ensure the shock’s specifications (such as travel and mounting options) match your bike’s geometry and intended use.

It is essential to check that the shock’s dimensions are compatible with your frame, especially for coil shocks, which may require different mounting hardware compared to air shocks.

By following these steps, you will have your Bomber CR Coil rear shock set up with optimal sag, improving your bike’s handling and performance on all terrains. Proper sag setup is the foundation of suspension tuning, allowing you to achieve a balanced and smooth ride for various riding conditions.