DCT
8:25-cv-02178
Fox Factory Inc v. Radflo Suspension Technology
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Fox Factory, Inc. (California)
- Defendant: Radflo Suspension Technology (California)
- Plaintiff’s Counsel: Hawkinson Yang LLP; Perilla Knox & Hildebrandt LLP
- Case Identification: 8:25-cv-02178, C.D. Cal., 09/26/2025
- Venue Allegations: Venue is alleged to be proper because Defendant resides in the district, maintains a regular and established place of business there, has committed alleged acts of infringement in the district, and a substantial part of the events giving rise to the claims occurred in the district.
- Core Dispute: Plaintiff alleges that Defendant’s line of Bypass Shock Absorbers infringes a patent related to an adjustable mounting mechanism for high-performance vehicle shock absorbers.
- Technical Context: The technology concerns high-performance shock absorbers for off-road vehicles, a market where components must fit a wide variety of custom vehicle configurations.
- Key Procedural History: The complaint alleges that Plaintiff sent Defendant a notice letter regarding the asserted patent on April 25, 2025, and a follow-up letter on July 15, 2025. Defendant allegedly responded on April 30, 2025, denying infringement. Plaintiff also alleges that after receiving the first notice letter, Defendant removed a promotional video of the accused product from its Instagram account.
Case Timeline
| Date | Event |
|---|---|
| 2006-02-13 | ’889 Patent Priority Date |
| 2015-10-27 | ’889 Patent Issue Date |
| 2025-04-25 | Plaintiff sends first notice letter to Defendant |
| 2025-04-30 | Defendant responds to notice letter |
| 2025-07-15 | Plaintiff sends follow-up letter to Defendant |
| 2025-09-26 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,169,889 - “FLUID PRESSURE OPERATED DEVICE WITH ADJUSTABLE POSITIONING OF MOUNTING ELEMENTS RELATIVE TO EXTERNALLY MOUNTED STRUCTURES,” Issued October 27, 2015
The Invention Explained
- Problem Addressed: The patent’s background section describes a problem in the high-performance shock absorber market where externally mounted components, such as fluid reservoirs or bypass tubes, are in fixed positions relative to the shock’s mounting points (’889 Patent, col. 1:40-47). This fixed orientation can create physical conflicts with a vehicle's structure, such as its fenders, preventing the shock from being installed on certain vehicles or requiring costly custom modifications (’889 Patent, col. 1:47-50).
- The Patented Solution: The invention provides an adapter assembly positioned between the main working cylinder and the body cap of the shock absorber (’889 Patent, Abstract). This assembly allows the body cap, which contains a mounting element (e.g., an eyelet), to be rotated and re-oriented relative to the working cylinder and its external structures (’889 Patent, col. 4:4-12). This adjustment can be performed without disassembling the shock's internal components or changing its overall length, enabling a standard shock to be adapted to various vehicle geometries (’889 Patent, col. 4:6-10).
- Technical Importance: The solution allows for mass-manufactured, high-performance shocks to be installed on a wider range of custom and modified vehicles without requiring re-machining of the shock itself (’889 Patent, col. 1:47-50).
Key Claims at a Glance
- The complaint asserts independent Claim 1 (’889 Patent, col. 5:21-48; Compl. ¶30).
- The essential elements of Claim 1 include:
- A working cylinder with a first and second end.
- A shaft that moves in and out of the first end, including a first mounting element.
- A body cap for attachment to the second end, including a second mounting element.
- An adapter assembly disposable between the cylinder and body cap, allowing the orientation of the second mounting element to be changed.
- The adapter assembly includes an adapter disk capable of rotation within the second end of the cylinder, where the body cap attaches to the disk via at least one threaded fastener.
- The second mounting element can be rotated without causing shaft movement, and the device's overall length remains constant during orientation changes.
- The complaint does not explicitly reserve the right to assert dependent claims.
III. The Accused Instrumentality
Product Identification
Defendant Radflo’s Bypass Shock Absorbers (the “Accused Products”) (Compl. ¶¶19, 28).
Functionality and Market Context
The complaint alleges the Accused Products are high-performance shock absorbers for off-road vehicles such as UTVs, trucks, and SUVs (Compl. ¶18). The central accused functionality is an adapter positioned between the damper cylinder and the body cap that allows the orientation of the body cap's mounting point to be adjusted, or "clocked" (Compl. ¶¶19, 40). A screenshot from a now-deleted promotional video shows the text "THESE ALLOW YOU TO CLOCK THE END" superimposed over the accused product, illustrating this rotational adjustment feature (Compl. p. 10). The complaint asserts that this structure is "identical to FOX Factory's patented External Bypass Shocks" (Compl. ¶21).
IV. Analysis of Infringement Allegations
’889 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a working cylinder having a first end and a second end | The Accused Products are shock absorbers that include a working cylinder. A provided screenshot points to the main body of the shock absorber (Compl. p. 8). | ¶¶33-34 | col. 2:39-40 |
| a shaft that moves into and out of the first end of the working cylinder... the shaft including a first mounting element attached thereto | The Accused Products include a shaft that moves in and out of the cylinder during compression and rebound and has a mounting element. | ¶¶35-36 | col. 2:40-45 |
| a body cap for attachment to the second end of the working cylinder opposite the shaft, the body cap including a second mounting element | The Accused Products include a body cap with a mounting element attached to the end of the cylinder opposite the shaft. A screenshot highlights this component, described as a "BOLT ON END CAP" (Compl. p. 9). | ¶¶37-38 | col. 2:45-53 |
| an adapter assembly disposable between the working cylinder and the body cap, the adapter assembly allowing orientation of the second mounting element of the body cap to be changed | The Accused Products allegedly include an adapter assembly between the cylinder and body cap that allows the orientation of the mounting element to be "clocked" or changed. | ¶¶39-40 | col. 3:51-54 |
| the adapter assembly includes an adapter disk that can be fit into the second end of the working cylinder and is capable of rotation... the body cap is attached to the adapter disk using at least one threaded fastener | The Accused Products' adapter assembly allegedly includes a rotatable adapter disk to which the body cap is attached with at least one threaded fastener. A screenshot shows a fastener being used to attach the body cap (Compl. p. 11). | ¶¶41-42 | col. 3:55-65 |
| the second mounting element can be rotated without causing movement of the shaft and a length of the fluid pressure operated device remains constant when the orientation... is changed | The Accused Products allegedly allow the second mounting element to be rotated while the shaft remains stationary and the overall length of the shock absorber remains constant. | ¶¶43-44 | col. 4:6-10 |
- Identified Points of Contention:
- Scope Questions: The dispute may turn on the definition of "adapter assembly." A question for the court could be whether Claim 1, which details an "adapter disk" and "threaded fastener," reads on the specific components and connection mechanism used in the Accused Products.
- Technical Questions: A central factual question will be how the Accused Products' rotational adjustment mechanism operates. The complaint alleges it functions by using an adapter disk and fastener as claimed (Compl. ¶¶41-42), but the provided visuals do not show the internal components of the assembly. The evidence presented will need to establish that the Accused Products contain these specific claimed structures and not an alternative mechanism for achieving rotation.
V. Key Claim Terms for Construction
- The Term: "adapter assembly"
- Context and Importance: This term is the central feature of the invention, as it describes the mechanism enabling the novel rotational adjustment. The entire infringement analysis depends on whether the accused structure falls within the scope of this term.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent describes the assembly's function as being "positioned intermediate the body cap 120 and damper cylinder 110" to attach the two parts and allow for reorientation (’889 Patent, col. 3:51-54). Plaintiff may argue that any structure performing this function between these components meets the definition.
- Evidence for a Narrower Interpretation: Claim 1 recites specific components of the assembly, namely "an adapter disk that can be fit into the second end of the working cylinder and is capable of rotation" and attachment via "at least one threaded fastener" (’889 Patent, col. 5:35-42). Furthermore, Claim 10 explicitly adds a "retainer ring" and a "seal" to the definition of the adapter assembly (’889 Patent, col. 6:58-59). Defendant may argue that the term "adapter assembly" as used in Claim 1 should be construed to require, at a minimum, the specific "adapter disk" and "threaded fastener" structure, and not just any means of rotation.
VI. Other Allegations
- Indirect Infringement: The prayer for relief seeks an injunction against "inducing others to directly infringe" (Compl. p. 13). However, the body of the complaint does not contain specific factual allegations to support a claim for indirect infringement, such as instructing users via manuals or advertisements to perform infringing acts.
- Willful Infringement: The complaint alleges that Defendant's infringement has been willful since at least April 25, 2025, the date it received Plaintiff's notice letter (Compl. ¶47). The complaint further alleges that Defendant had "knowledge of FOX Factory's patented design and intentionally copied the design prior to offering for sale" the Accused Products, suggesting a basis for pre-suit willfulness as well (Compl. ¶22).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of claim construction: how narrowly will the court define the term "adapter assembly"? Will the term be limited to the specific embodiment comprising an "adapter disk" and "threaded fastener" as detailed in the patent's claims and specification, or can it be construed more broadly to encompass other mechanical structures that achieve the same rotational function between the body cap and cylinder?
- A key evidentiary question will be one of structural identity: what is the precise mechanical structure of the accused Radflo shock's adjustment feature? The case will likely require a technical deep-dive, potentially through reverse engineering or discovery, to determine if the Accused Products' components and their method of operation map onto the specific limitations of Claim 1.