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IPR2017-00118

Fox Factory Holding Corp v. SRam LLC

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1. Case Identification

2. Patent Overview

  • Title: CHAINRING
  • Brief Description: The ’027 patent describes a bicycle chainring for a front crankset designed to improve chain retention. The key features include a plurality of teeth with alternatingly arranged narrow and wide tooth profiles, where at least some of the tooth tips are offset from a central plane toward the inboard side of the chainring.

3. Grounds for Unpatentability

Ground 1: Obviousness over Thompson and JP-Shimano - Claims 7, 8, 11, 12, 20-22, 25, and 26 are obvious over Thompson in view of JP-Shimano.

  • Prior Art Relied Upon: Thompson (Patent 6,273,836) and JP-Shimano (Japanese Utility Model Kokai No. S56-42489).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Thompson disclosed all limitations of the independent claims except for the alternating narrow/wide teeth. Thompson taught a bicycle chain sprocket with stiffening fins that resulted in the teeth being offset toward the inboard side of the chainring to prevent deformation and chain disengagement. Petitioner asserted that JP-Shimano, a Japanese utility model application from 1981, explicitly taught a bicycle chainring with alternating wide and narrow teeth to engage the outer and inner links of a chain, respectively. This configuration was also intended to prevent the chain from dropping.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Thompson and JP-Shimano because both references addressed the same well-known problem of preventing chain disengagement from a chainring. Thompson achieved this through axial reinforcement and an inboard offset, while JP-Shimano used an alternating tooth profile. Petitioner contended that a POSITA would have been motivated to combine these known solutions to achieve improved and more reliable chain retention, a predictable result. This motivation was argued to be particularly strong for a solitary front chainring, as disclosed in Thompson, which does not require the chain to disengage for shifting.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because the combination involved applying a known tooth profile (JP-Shimano) to a known chainring structure (Thompson). This was presented as a straightforward application of known techniques to yield predictable improvements in chain retention.

Ground 2: Obviousness over Thompson, JP-Shimano, and Hattan - Claims 9, 10, 23, and 24 are obvious over the combination of Thompson, JP-Shimano, and Hattan.

  • Prior Art Relied Upon: Thompson (Patent 6,273,836), JP-Shimano (Japanese Utility Model Kokai No. S56-42489), and Hattan (Patent 3,375,022).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination in Ground 1 to address claims requiring specific tooth thickness, namely that a group of teeth "fills at least 75 percent of an axial distance" defined by the chain link spaces. Petitioner argued that Hattan taught a bicycle sprocket wheel where the teeth were dimensioned to have a high degree of "axial fill" within the inner link spaces of a standard chain, disclosing a preferred range corresponding to 74.6% to 96% axial fill. Hattan’s stated purpose for this sizing was to ensure proper chain interengagement and prevent the chain from jumping off the sprocket.
    • Motivation to Combine: The motivation to add Hattan's teachings was to further enhance the chain retention of the Thompson/JP-Shimano combination. Since a POSITA was already focused on improving chain retention, it would have been obvious to incorporate Hattan's teachings on optimal tooth thickness, another known technique for achieving the same goal. Petitioner argued that sizing teeth for a high axial fill was a routine design choice for a POSITA seeking to maximize chain engagement.
    • Expectation of Success: Success was expected because it involved applying known and preferred tooth dimensions (from Hattan) to the alternating tooth profiles of the proposed Thompson/JP-Shimano combination. This was characterized as a mere optimization of a known design parameter to enhance a predictable function.

Ground 3: Obviousness over Dake and Martin - Claims 7, 8, 11, 20-22, and 25 are obvious over Dake in view of Martin.

  • Prior Art Relied Upon: Dake (Patent 556,254) and Martin (Patent 4,174,642).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground presented an alternative combination of older prior art to arrive at the same invention. Petitioner argued that Dake, a patent from 1896, disclosed a sprocket wheel "especially adapted for bicycles" where the teeth were offset toward the inboard side of the sprocket. Martin taught a chain drive sprocket with alternating wide and narrow teeth designed to prevent "chain slippage" and ensure proper engagement with a roller chain. Together, Dake provided the inboard offset feature, and Martin provided the alternating tooth profile.
    • Motivation to Combine: The motivation was identical to Ground 1: to improve chain engagement and retention. Martin explicitly taught its narrow/wide tooth arrangement to prevent chain disengagement. A POSITA would have found it obvious to apply this known tooth design to another bicycle chainring, such as the one in Dake, to gain its known benefits. Petitioner emphasized that combining these known features was an obvious design choice to solve a persistent problem in the field.
    • Expectation of Success: A POSITA would have expected success in combining the teachings of Dake and Martin, as it involved modifying the teeth of a known chainring (Dake) with a known tooth profile (Martin) to achieve the predictable result of better chain retention.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge based on Dake, Martin, and Hattan (Ground 4), which paralleled the logic of Ground 2 by adding Hattan's axial fill teachings to the Dake/Martin combination. Petitioner also noted that Martin could be substituted for JP-Shimano in Grounds 1 and 2, and vice versa for Grounds 3 and 4 (Ground 5).

4. Key Claim Construction Positions

  • "Teeth": Petitioner argued that the term "teeth" should be construed as "asymmetrical teeth with the inboard and outboard sides of the teeth not being mirror images of each other." This position was based on prosecution history disclaimer, where the applicant allegedly distinguished the invention over the symmetrical teeth of Martin by arguing for "unique asymmetrical tooth features."
  • "Offset from the plane...": Petitioner argued this phrase should be construed as "positioned on the inboard side of a center line that bisects the plurality of teeth." This was based on the patent’s original Figure 10. Petitioner contended the Patent Owner improperly amended the figure during prosecution to show the plane bisecting the entire chainring body, which constituted new matter, and that the original figure properly defined the scope of the offset.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 7-12 and 20-26 of the ’027 patent as unpatentable under 35 U.S.C. §103.