What is Optimal?

When optimizing a suspension fork’s performance, the travel range is broken down into three portions , the initial stroke, the mid stroke, and the end stroke. Each respective part of the travel has optimal characteristics for maximizing the suspension’s performance.

Optimal Initial Stroke

The optimal initial stroke helps maintain traction and small bump sensitivity. Maximizing the suppleness of the initial stoke helps keep the tire’s continuous contact with the riding surface, and keep the suspension as sensitive as possible to small bumps.

Optimal Mid Stroke

The optimal mid stroke is supportive to avoid diving and blowing through travel to maintain the bike’s ideal geometry. Ample mid-stroke support allows for better cornering and braking performance as well as a more stable ride.

Optimal End Stroke

The optimal end stroke provides support for big hits and oh-shit moments based on each rider’s needs and riding style. Adjustable bottom out resistance that does not compromise small bump compliance or mid stroke support allows for fine tuning and customization.




Designed, tested, and manufactured in Durango, Colorado, the RUNT by DSD is the original dual chamber air spring cartridge. The patent pending design provides a near linear compression curve for a “coil-like” feel while maintaining infinite adjustability. 

  • Easy Drop-In Installation

  • Half the price of a coil conversion

  • Coil like suppleness and mid-stroke support

  • Built in tunable progression or “bottom out resistance”

  • 1/2 Lb Lighter than coil conversions and only 20 grams heavier than same amount of tokens or spacers

  • Maintains your fork’s air spring compatibility.


The issue with air springs…

A steady linear compression is very tough to achieve with air sprung suspension because air naturally compresses at an exponential rate. Because of this, air forks naturally lack mid-stroke support. In order to overcome the lack of support, most manufacturers have unnecessarily stiff compression damping. As a result, most riders begin to run less and less air pressure to maintain efficient small bump compliance. With the air spring’s lack of mid stoke support, most riders think that by adding progression to their suspension with volume spacers will help get some support back, but it actually causes a dramatic spike towards the end of the travel. This contributes to a less than optimal suspension set up, leaving riders sacrificing small bump plushness for stiffer cornering performance or vice versa. The RUNT effectively uses the progressive nature of air, providing a liner rate, and giving riders optimal suspension performance.

How does it work?

This animation demonstrates the liner progression of the RUNT. When the low or main air chamber’s pressure equalizes the high or small chamber, the floating piston begins to move, allowing for a linear pressure curve previously impossible in air sprung forks.

Infinite adjustability…

The RUNT still uses air, so unlike a coil spring, the progressiveness of the curve is infinitely adjustable. For example, more aggressive riders looking for a bit more bottom out resistance, can add air to the high chamber to provide a more progressive curve. Increasing the progressiveness with the RUNT does not effect the small bump compliance, instead, it provides more bottom-out resistance from the end of the mid-stroke through the end of the travel.


Upgrade your fork…

Get coil-like performance, without the coil