Stock Charger dampers - 3.0, 3.1, and even the new 3.2 - all run a digressive pistons from the factory. On a dyno that looks like a lot of damping force right off the top at low shaft speeds, then damping flattens out as you go faster. On trail that translates to firm support when you're pumping or in a berm, but it blows off quickly on sharp hits. It feels initially supportive, then harsh because it's too deep mid-way through the travel, then blows through the end stroke and is unsupportive. Digressive piston designs make you rely on the spring(psi) for support on high-speed terrain and can be harsh initially.

The Fluid Focus linear piston flips that relationship. The porting and flow path are designed so damping force builds in a much more straight-line(linear), proportional to shaft speed. Low speed is softer, so the wheel isn't getting hung up on roots and brake bumps, and high speed keeps building so you don't get that harsh spike. Pairing our piston with the new Linear XL air spring on the 2026 forks makes sense. The damper builds support while the air spring ramps up less, both sides work together to create a cohesive package. You want the damper to be speed-sensitive and the spring to be position-sensitive.

That's where the custom shim stack comes in. The piston is the foundation; the shim stack is the fine tuning. It's a stack of thin washers that deflect to let oil through. By changing diameter, thickness, number, and order, you set exactly when and how much they open.

For example, on a stock tune, RockShox must make one stack work for a 150lb rider in the Midwest and a 200lb rider in bike park. With a custom stack you can tune tune for any situation:

1.    Low-speed bleed for bike balance under your body weight - that gives you traction and that planted feeling in off-camber and loose corners.

2.    Mid-speed support - That's where you feel support in berms, G-outs, and when you load the front end. A linear piston paired with a proper mid valve shim stack and a rebound tune to match the PSI, holds you up without packing.

3.    High-speed blowoff - how it handles a square-edge hit at speed. You can make it open progressively instead of spiking, so you get less hand fatigue and the front wheel recovers faster.

So, on trial, the combo feels like more grip on the first inch of travel over chatter, less diving when you brake hard, and more predictable ramp at the end of a big hit instead of harshness.

 Fluid Focus linear piston for the Rockshox Charger 3.0, 3.1, and 3.2 damper, lets you run less compression from the adjuster and get the support from the shim instead, which is way more consistent lap to lap.