{{ data.msg }}

Your browser does not support all of our website’s functionality. For an improved shopping experience, we recommend that you use the most recent versions of Google Chrome, Safari, or Firefox.

WHAT’S A “LINEAR” AIR SPRING?

AND WHY DOES IT MATTER?

RockShox has been hunting down a linear, more coil-like air spring for our last few versions of suspension, iterating on what our engineers have learned year over year. A linear spring rate means that your suspension's spring responds to obstacles and input in a very consistent and predictable way regardless of where the suspension is in its travel. With the launch of our new LinearXL air spring in 2026, found in our BoXXer, ZEB, and Lyrik forks, we've made our most linear air spring to date thanks to a whole host of new technologies. Let's take a deeper look at different spring rates so you can see what LinearXL does for your ride.

RockShox LinearXL Air Spring

Before we get too far into it, let’s define what a spring rate is: the ratio of force absorbed from the trail or rider (measured in pounds), per the distance the spring moves (measured in mm). A spring curve is a graph that visually maps how the spring force changes across the entire length of the fork's travel. There are linear spring curves, which we get with coil springs, that are a perfectly straight line as they compress at a constant rate. There are also progressive spring curves, which we get with air springs, that have a changing spring rate as they compress. We’ll look at both linear and progressive spring rates to get an idea of how they work, and then we’ll dive into LinearXL.

LINEAR SPRING RATE

As you may (or may not) be aware, there is an ongoing battle between coil springs and air springs. Coil springs are known for their very consistent feel—it’s easy to initiate travel and stay consistent all the way through to bottom out. They naturally have a linear spring rate: as a coil spring compresses, the force needed to compress the spring increases at a constant rate: each additional unit of travel requires the same additional amount of force. For example: if 10mm of travel requires 25lbs of force, 20mm would require an additional 25lbs of force, so 50lbs total, and so on.

Related Image

However, that very linear rate also means that the end stroke can feel harsh. As there is no additional support when you're deep in travel and have a big bottom-out event, you can easily blow through all your travel.

PROGRESSIVE SPRING RATE

Now, we don’t see a lot of coil springs in forks anymore, and that’s mostly because of weight and tunability. Coil springs weigh more than air springs (air molecules are lighter than steel), and they aren’t infinitely tunable like an air spring. Air springs are typically designed to have a progressive spring rate: as an air spring compresses, the force required to move through the travel changes.

Related Image

For example, with a traditional air spring, we see a bit of a rollercoaster curve. At the beginning of travel, we see a “nose” that indicates more force is needed to initiate travel. In the mid-stroke, there is a “hammock” that indicates a little less force is needed in the middle of travel. The ramp at the end of travel indicates that more force is required to reach full travel, which helps provide more bottom-out resistance.

Related Image

BREAKING IT DOWN

We mentioned above that we’ve been working to make our air springs more linear. To be clear, that doesn’t mean that we want to make it perfectly linear like a coil spring, just that we’re aiming to smooth out the spring rate to make it feel more linear-like for the first 70% of the fork’s travel. However, we do want the control that a typical air spring delivers in the last 30% of travel, as that end ramp means that you have the support to charge into whatever the trail throws at you.

Let’s break a spring chart down into thirds so we can walk through what’s happening with LinearXL as it compresses.

INITIAL TRAVEL

This graph shows the first 20% of a fork’s travel, and features three different spring curves. The red represents a “traditional” air spring curve, blue is our newest air spring: LinearXL, and the dotted line is a linear coil spring. The curves may look pretty close through all of these graphs, but it’s important to note that tiny changes on a graph equal big change in ride feel.

Related Image

Here, we’re looking at the beginning of the fork’s travel, right as the fork begins to compress from top of the stroke. Overall force at the beginning of travel is very low for all springs. However, you’ll notice that LinearXL’s blue line is lower than the traditional air spring’s red line, which means that less force is needed to get the LinearXL air spring to move than the traditional spring.

This translates to:

  • A softer feeling as you start compressing the suspension toward mid-travel.
  • A more predictable and natural feeling spring, as the force needed to compress the fork has a more consistent rate, similar to a coil spring (the dotted line).

MID-TRAVEL

Now let’s move over to the mid-stroke portion of the curves, which is the middle 50% of travel. You'll notice that the blue line sits above the red line, which indicates that LinearXL's air spring is generating more force—providing more support through the middle of the stroke than a traditional air spring.

Related Image

This is important for two reasons:

  1. There's more mid-travel support.
  2. It's more predictable. 

  
What does that mean for ride feel?

More mid-travel support: The LinearXL air spring generates more force through the mid‑stroke than the traditional air spring. This provides better support, helping keep the rider higher in the travel instead of pushing them deeper into travel when that may not be necessary or wanted.

It's more predictable: And humans like predictability, even if it's subconscious. LinearXL's transition from initial travel into mid-travel is smooth and imperceptible to the rider. As it travels through the mid-stroke, there's increased support, which means that the fork's response to impacts is more consistent and predictable. When things are coming at you quickly, like for our World Cup racers, knowing exactly how the spring will react means riders can focus on the track instead of trying to manage their suspension.

FULL-TRAVEL

Now let’s look at the last 30% of travel.

Related Image

Here we can see the red line change rate again, ramping up at the end-stroke of the curve, indicating that more force is needed to reach full travel. This rate change is how traditional progressive air springs have typically controlled bottom-out—another example of the multiple rate changes we've seen throughout the curve to this point, including the mid-travel “hammock” we talked about above. 

The blue LinearXL spring curve represents a more linear end-stroke curve. While consistent (and therefore predictable), it provides the rider with the linear feel deep into the travel. But we wanted to have a more refined and tunable bottom-out experience, so we introduced Adjustable Bottom Out (ABO).

ABO is a mechanical bottom-out system that specifically manages how your fork feels when it bottoms out. Ultimate models offer up to 10mm of adjustment across 8 clicks, so riders can choose how much bottom-out support they want. The green line on the chart represents 0 clicks of ABO, while the purple line represents all 8 clicks of ABO added for the most bottom-out support, and each click will fall in between those lines. Just remember, the steeper the curve, the more force it will take to reach full travel.

Select+ models feature an internally adjustable, 3-position ABO system. Both the ZEB gen B and Lyrik gen E Select+ and Select models can be upgraded to include the Ultimate ABO.

Learn more about ABO

WHY IT MATTERS

  

Related Image

The takeaway: LinearXL means more trust. When your fork feels consistent, your subconscious can predict how it will react in different scenarios. Consistent and predictable means you can trust your bike to handle whatever you (or the trail) has to offer. Curious about the technologies that make up LinearXL? Dive deeper.

LEARN MORE

BUTTERWAGONTECH

Read more

COMPRESSION KNOB LOGIC

Read more