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SRAM sues Princeton Carbon Works for patent infringement on aero wheels

Published March 19, 2021
SRAM claims that PCW is infringing on its patent for a rim shape inspired by a humpback whale flipper.

CHICAGO (BRAIN) — SRAM Inc. is suing Princeton Carbon Works, Inc. for patent infringement. SRAM says that the wavy rim shape on Princeton's carbon road wheels infringes on its patent for a rim shape inspired in part by a humpback whale flipper. SRAM uses that design on its Zipp 454 Carbon NSW wheels, which retail for up to $4,000 per pair.

SRAM's wheels rely on two patents from inventor Dimitrios Katsanis. The first patent was issued in 2017 and a related patent was issued in 2020. Katsanis assigned both to Metron IP Limited, a Nottingham, UK, company, who in turn assigned them to SRAM. It's not clear when the patent was assigned to SRAM.

The patents describe a rim or spokes with an "undulating configuration" that is said to reduce aerodynamic drag, especially in crosswinds. Among the publications cited in the patents is "Hydrodynamic Design of the Humpback Whale Flipper," published in the Journal of Morphology in 1995.

Princeton, which entered the market in about 2018, offers wheels with a rim shape that resembles the Zipp design, at least superficially. Princeton says its rim shape is sinusoidal. The Princeton undulations appear symmetric, while the Zipp shape is more like a sawtooth.

Many consumer media reviews of the Princeton wheels have remarked on the resemblance. 

"Princeton CarbonWorks has had a bit of an uphill battle to ensure riders understand there’s a major difference between its sinusoidal rim shape and the biomimicry shape that Zipp touts on its 454 NSW wheels. Aesthetically, the two designs look similar, but according to Princeton, they work vastly differently," a Sept. 2020 review on began. 

In a 2018 CyclingTips review, Princeton co-founder Paul Daniels is quoted hinting that he might be open to licensing the design. “It’s in Princeton CarbonWorks’ interest to spend our resources developing next-level product that surpasses our competitors. If we have to pay a royalty along the way because economics dictate that’s a better decision than litigating patent law, then so be it," Daniels said in the article.

SRAM's complaint charges that Princeton was aware of SRAM's patent and continued to market its wheels. It's asking for tripled damages for willful infringement and for Princeton to be ordered to deliver up for destruction any remaining inventory. The civil complaint was filed Friday; SRAM's lawyers asked the court to issue a summons for Princeton, which hadn't been granted by the end of the day.

A photo of a Princeton Carbon Wheelworks wheel from the SRAM complaint.
Topics associated with this article: Lawsuits/legal

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