 The PDS shock technology has been kept alive by KTM and WP suspension, despite the whole industry plowing on to linkage style shocks. But how can a shock without linkage endure this? Without blowing apart. Let's find all about WP's PDS shock from the Proline. Before starting to learn how this system works, I strongly recommend you to first take a look at the off-road engineered video that explains how a traditional shock works. WP's PDS shock stands for Progressive Damping System and can equip one of the most common bikes around, KTM Zenduro and Dual Spork Range. WP's PDS shock is directly connected to the swing arm and doesn't require any linkage system which makes the underfloor of the bike really slick. On the outside, the PDS shock is slightly shorter but it has the same components such as the nitrogen chamber to pressurize the oil, a high-speed and low-speed compression damping adjusters on top and a rebound damping adjuster at the bottom. On the inside is where things are really different to linkage shocks. On the PDS shock, there is an extra piston compared to linkage system shocks. The bottom piston is responsible for the main damping character with a compression and rebound shim stacks. The second piston has a slightly smaller diameter and is responsible for providing additional compression damping at the end of the compression stroke. This secondary piston provides a position-sensitive damping, much like the linkage system does. So let's understand how a PDS shock works, step-by-step. While compressing, the same volume of the piston rod entering the shock's body is pushed into the oil reservoir. Initially, the oil flows around the top piston and through the low-speed orifice on the main piston. Once the pressure starts building, the low-speed compression damping shim stack opens on the main piston, increasing the oil flow and providing less damping. If the oil pressure keeps increasing, the high-speed shim stack on the main piston opens, increasing the oil flow and providing less damping. When the secondary piston enters the cup inside the shock body, it means the shock is nearly bottoming out. At this point, the oil inside the cup has nowhere to go but through the secondary piston, which increases the overall damping of the shock, thus providing a progressive damping character. On rebound, the play on the secondary piston provides an oil bypass to refill the cup, without creating significant damping. The oil below the main piston is pushed through the low-speed orifice, but like in a compression stroke, the oil pressure keeps building and the rebound shim stack on the main piston opens, allowing more oil to exit the chamber below, generating rebound damping and controlling the shock's extension. While this happens, the check valve on the adjuster opens, allowing the oil inside the reservoir to fill up the shock's body. The secondary piston increases the damping ability of the shock without having to increase its travel, much like a mid-speed valve. However, it is position-sensitive since this circuit only provides damping once the piston enters the cup. The PDS shock might have some drawbacks, as with everything, but it is true that it allows the dirt bike manufacturer to eliminate all bushings and bearings of the linkage system, improving the reliability of the bike and rideability over very tough terrain. That ain't a bad idea. If you have any questions, leave them in the comments below and if you want to learn how to take full advantage of your suspension adjustments, take a look at our online suspension courses available on our website. Knowledge is power. Thank you for watching and don't forget to subscribe to keep learning with us.