PTAB

IPR2017-01440

Fox Factory Inc v. SRam LLC

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: CHAINRING
  • Brief Description: The ’250 patent discloses a bicycle chainring for a front crankset featuring alternating wide and narrow teeth. The invention's key feature is that the wide teeth have a maximum axial width that "fills at least 80 percent" of the space defined by a roller drive chain's outer links to improve chain retention.

3. Grounds for Unpatentability

Ground 1: Obviousness over JP-Shimano in view of Hattan

  • Claims Challenged: 1-26 are obvious over JP-Shimano in view of Hattan.
  • Prior Art Relied Upon: JP-Shimano (Japanese Utility Model Application No. S56-42489) and Hattan (Patent 3,375,022).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that JP-Shimano taught the foundational structure of the claimed invention: a bicycle chainring with alternating wide and narrow teeth designed to engage a roller chain’s outer and inner link spaces, respectively. This structure was intended to prevent the chain from dropping. However, JP-Shimano did not explicitly quantify the tooth thickness relative to the link space, a limitation referred to as Axial Fill (AF). Hattan, in turn, addressed the same problem of chain retention and explicitly disclosed sizing sprocket teeth to achieve high AF ratios, teaching a "preferred" range of 74.6% to 96% and a "desirable" AF of about 85.3% for inner link spaces. Petitioner contended that applying Hattan’s AF teachings to JP-Shimano’s wide teeth would render the limitations of independent claims 1 and 14 obvious, including the requirement of at least 80% AF.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would have been motivated to improve the chain retention of the JP-Shimano chainring. Both JP-Shimano and Hattan explicitly stated their purpose was to prevent chain detachment. A POSITA would have recognized that incorporating Hattan’s known method of using high AF ratios into JP-Shimano’s alternating tooth design was a predictable way to further enhance performance. The combination was presented as an application of a known technique (high AF) to a known device (narrow-wide chainring) to improve its function.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because combining these known elements would yield only predictable results. Petitioner asserted that increasing the tooth thickness to more fully occupy the chain link space, as taught by Hattan, would predictably improve chain stability on the JP-Shimano chainring. The petition emphasized that AF is a recognized result-effective variable, making its optimization a matter of routine design choice rather than innovation.

Ground 2: Obviousness over Hattan in view of JP-Shimano

  • Claims Challenged: 1-26 are obvious over Hattan in view of JP-Shimano.
  • Prior Art Relied Upon: Hattan (Patent 3,375,022) and JP-Shimano (Japanese Utility Model Application No. S56-42489).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground reverses the primary and secondary references. Petitioner argued that Hattan taught the key concept of using high AF ratios (up to 96%, desirably ~85.3%) in a solitary chainring to ensure proper chain engagement and prevent detachment. However, Hattan’s teeth were of uniform thickness. JP-Shimano taught that using an alternating narrow and wide tooth profile was another effective method for improving chain retention by specifically engaging both the inner and outer link spaces of a roller chain. Petitioner asserted that modifying Hattan's high-AF chainring to incorporate the alternating narrow-wide tooth profile taught by JP-Shimano would arrive at the claimed invention.
    • Motivation to Combine: A POSITA, starting with Hattan’s chainring, would have been motivated to further improve its chain retention capabilities. JP-Shimano provided a well-understood solution for preventing chain drop by using alternating tooth widths. A POSITA would have been motivated to combine the benefits of both systems—Hattan’s tight-fitting high AF and JP-Shimano’s alternating tooth engagement—to create a chainring with superior chain retention. This was particularly relevant for solitary front chainrings where chain shifting is not a concern, allowing for maximization of retention features.
    • Expectation of Success: A POSITA would have expected the combination to succeed. Applying the alternating tooth profile of JP-Shimano to the teeth of the Hattan chainring would predictably result in a component that benefits from both retention strategies. The petition argued this modification would not alter the fundamental structure of Hattan's apparatus and would predictably yield the claimed chainring with its enhanced engagement characteristics.

4. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1-26 of the ’250 patent as unpatentable under 35 U.S.C. §103.