Ohlins FKS 508 NIX 30 Front Fork Cartridge Kit for Harley FXFB/FXLRS/FXLRST

Vehicle Fitment

• 2018-2023 Harley-Davidson Softail Fat Bob 107 (FXFB)
• 2018-2023 Harley-Davidson Softail Fat Bob 114 (FXFBS)
• 2020-2023 Harley-Davidson Softail Low Rider S (FXLRS)
• 2022-2023 Harley-Davidson Softail Low Rider ST (FXLRST)

Fitment Notes

• Fits all models equipped with the 43mm inverted front fork with standard-length fork tubes only
• May fit select 2017 model year bikes with the base bolt version of the standard fork - verify fork bottom before ordering
• Fork springs and fork oil (2 liters) are required and sold separately - contact an Ohlins Service Center for spring rate recommendations based on rider weight and preference
• Professional installation by an Ohlins-authorized service center is strongly recommended

Features

• NIX 30 technology developed from WSBK, World Supersport, and AMA Superbike racing programs
• Separate compression damping (left leg) and rebound damping (right leg) via proven NIX design for precise, independent adjustment
• 30mm piston diameter delivers superior damping consistency and response over OEM cartridges
• External compression, rebound, and spring preload adjusters accessible from black top caps - no fork removal required to change settings
• Bolt-on installation into OEM fork tubes - no fork modification required
• Single-cylinder sealed piston chamber allows oil flow only through the shim stack for consistent, race-derived damping behavior
• Ohlins Setting Bank included - provides baseline damping setups for various riding styles and conditions
• Black top cap design integrates cleanly with the stock fork appearance

Specifications

• Part Number: FKS 508
• System: NIX 30 Street Cartridge Kit
• Piston Diameter: 30mm
• Fork Compatibility: 43mm Inverted Front Fork (OEM tubes)
• Position: Front (Left & Right)
• Compression Adjustment: External, Left Leg
• Rebound Adjustment: External, Right Leg
• Spring Preload Adjustment: External, accessible from top caps
• Springs: Not included - sold separately
• Fork Oil: Not included - 2 liters required (sold separately)

Included Components

• 1x Left Leg NIX 30 Cartridge (Compression)
• 1x Right Leg NIX 30 Cartridge (Rebound)
• 1x Ohlins Setting Bank Reference Card
• 1x Installation Instruction Sheet

Product Description

The Ohlins FKS 508 is a bolt-on NIX 30 front fork cartridge kit engineered specifically for Harley-Davidson Softail models equipped with the 43mm inverted fork. Developed from decades of top-tier racing experience - including WSBK and AMA Superbike programs - the NIX 30 system replaces the OEM damper internals with a race-derived 30mm piston cartridge that dramatically improves fork feel, stability, and adjustability without requiring fork leg replacement.

The NIX design separates compression damping to the left leg and rebound damping to the right, allowing each function to be dialed in independently for a more precise and consistent ride. External adjusters on both legs - along with spring preload - are all accessible from the top caps, making on-the-fly tuning simple. Fork springs and oil are required but sold separately, allowing riders to select spring rates tailored to their weight and riding style with guidance from Ohlins' included Setting Bank.