Understanding Volume Spacers

Understanding the Role of Volume Spacers in Suspension Performance

As mountain bikers, we're always looking for ways to fine-tune our bike's suspension to achieve the perfect ride. One of the most effective and often overlooked adjustments we can make is the use of volume spacers. These small, seemingly innocuous pieces of plastic can have a significant impact on how your suspension performs, affecting everything from small-bump compliance to end-stroke ramp and bottom-out resistance.

In this comprehensive guide, we'll dive deep into the world of volume spacers, exploring what they are, how they work, and when to use them to optimize your bike's handling and responsiveness. Whether you're a seasoned suspension tuner or just starting to explore the world of suspension setup, this article will provide you with the knowledge and tools to make informed decisions about your bike's setup.

What Are Volume Spacers?

Volume spacers, also known as air volume reducers or tokens, are small, cylindrical inserts that are placed inside the positive air chamber of your bike's suspension components, such as forks and shocks. Their primary function is to reduce the available air volume within the spring, effectively altering the spring rate and progression of the suspension.

In a standard air spring suspension system, the positive air chamber is responsible for supporting the bike's sprung mass (the weight of the bike and rider) and providing the necessary spring force to absorb impacts and smooth out the terrain. As the suspension compresses, the air in the positive chamber is compressed, creating an opposing force that pushes the suspension back to its original position.

By installing volume spacers, you're essentially reducing the available volume of the positive air chamber, which in turn increases the spring rate and progression of the suspension. This means that as the suspension compresses, the air pressure rises more rapidly, creating a more supportive and progressive feel throughout the travel.

How Do Volume Spacers Work?

To understand how volume spacers affect the performance of your suspension, it's helpful to have a basic understanding of the underlying physics and principles at play.

The Science of Air Springs

Air springs, unlike their coil spring counterparts, exhibit a naturally progressive spring rate. This means that as the suspension compresses, the air pressure within the positive chamber increases exponentially, resulting in a non-linear force curve.

The relationship between the volume and pressure of an air spring is governed by Boyle's law, which states that the pressure of a gas is inversely proportional to its volume, assuming the temperature remains constant. In other words, as the volume of the air chamber decreases, the pressure within that chamber increases.

This progressive nature of air springs is both a blessing and a curse. On one hand, it allows for a more supple and responsive feel off the top of the travel, as the initial spring rate is relatively low. However, as the suspension compresses further, the spring rate increases dramatically, leading to a more supportive and stable feel towards the end of the travel.

The Role of Volume Spacers

Volume spacers play a crucial role in tuning the progression and ramp-up of an air spring suspension. By reducing the available volume of the positive air chamber, the spring rate and progression of the suspension are increased.

Imagine a scenario where you have a suspension fork with 170mm of travel. Without any volume spacers installed, the air spring would have a relatively linear feel throughout the travel, with a gradual increase in spring rate as the suspension compresses. However, by adding volume spacers, you can effectively reduce the available volume of the positive air chamber, causing the spring rate to increase more rapidly as the suspension compresses.

This increased progression can be beneficial in a variety of situations, such as when riding steep, technical terrain or under heavy braking, where you want the suspension to resist bottoming out and maintain a stable, predictable feel. Conversely, if you're riding smoother trails and want a more supple, responsive feel, you may opt to remove some or all of the volume spacers.

Choosing the Right Volume Spacers

When it comes to selecting the appropriate volume spacers for your bike, there are a few key factors to consider:

Suspension Design and Travel

The specific volume spacer requirements can vary depending on the suspension design and travel of your bike. For example, a fork with 160mm of travel may require fewer volume spacers than a fork with 180mm of travel to achieve a similar feel.

Manufacturers often provide guidance on the recommended number of volume spacers for their suspension components, taking into account factors such as travel, intended use, and rider weight. It's always a good idea to consult with the manufacturer or a suspension expert to ensure you're starting with the optimal setup for your bike and riding style.

Riding Terrain and Conditions

The terrain and conditions you typically ride in can also influence the number of volume spacers you'll want to use. For example, if you frequently ride steep, technical trails with heavy braking, you may benefit from adding more volume spacers to increase the progression and bottom-out resistance of your suspension.

Conversely, if you primarily ride smooth, flowy trails, you may want to use fewer volume spacers to maintain a more supple, responsive feel off the top of the travel. It's often helpful to experiment with different volume spacer configurations to find the sweet spot for your local trails and riding style.

Rider Weight and Preferences

Your personal riding style and preferences can also play a role in determining the optimal volume spacer setup. Heavier riders may require more volume spacers to achieve the desired spring rate and progression, while lighter riders may prefer a more linear, responsive feel.

Additionally, some riders may simply prefer a more progressive or a more linear suspension feel, regardless of their weight. Experimenting with different volume spacer configurations and paying attention to how the changes affect the overall ride quality can help you find the perfect setup for your individual needs.

Installing Volume Spacers

The process of installing volume spacers can vary slightly depending on the specific suspension components on your bike, but the general steps are relatively straightforward:

Forks

• Remove the top cap of the fork.
• Carefully extract the existing air spring assembly.
• Insert the desired number of volume spacers into the positive air chamber.
• Reassemble the air spring and replace the top cap.
• Adjust the air pressure as needed to achieve the desired sag and ride quality.

Shocks

• Depressurize the shock by releasing the air valve.
• Remove the air can (the outer sleeve of the shock).
• Insert the volume spacers into the positive air chamber.
• Reassemble the air can and pressurize the shock to the desired setting.
• Adjust the air pressure as needed to achieve the desired sag and ride quality.

It's important to note that the specific installation process may vary depending on the suspension manufacturer and model. Always refer to the manufacturer's instructions or consult with a suspension expert to ensure you're following the correct procedures.

Experimenting with Volume Spacers

One of the best ways to understand the impact of volume spacers on your suspension performance is to experiment with different configurations. As mentioned earlier, the optimal number of volume spacers can vary depending on your bike, riding style, and terrain.

To get started, we recommend keeping the air pressure in your suspension components the same and only adjusting the number of volume spacers. This will allow you to isolate the effect of the volume spacers and better understand how they influence the suspension's feel and performance.

Start with the manufacturer's recommended setup and go for a ride. Pay attention to how the suspension feels throughout the travel, particularly in areas where you're applying the most force, such as steep descents, heavy braking, and technical terrain. If the suspension feels too progressive or resistant to bottoming out, try removing a volume spacer or two. Conversely, if the suspension feels too linear and prone to bottoming out, add a volume spacer or two.

Remember, the goal is to find the sweet spot where the suspension provides the optimal balance of small-bump compliance, mid-stroke support, and end-stroke ramp-up. It may take some trial and error, but the effort will be well worth it when you find the perfect setup for your bike and riding style.