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TECH NEWS
SRAM patent drawingSRAM sues Princeton Carbon Works for patent infringement of wavy rim on aero wheels
SRAM is suing Princeton Carbon Works for infringing a patent relating to an undulating rim design that is said to reduce aerodynamic drag and side force, which is a factor when riding in crosswinds.
SRAM says that the wavy rim shape on Princeton's 6560 carbon road wheel infringes its patent for the rim design that features on its Zipp 454 Carbon NSW wheels.
“SRAM's wheels rely on two patents from inventor Dimitris 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,” Bicycle Retailer reports.
Katsanis is best known in the cycling world for designing track bikes used by Team GB.
SRAM’s patented rim shape is in part inspired by a humpback whale, with the "Hydrodynamic Design of the Humpback Whale Flipper," published in the Journal of Morphology in 1995, cited in the patent. The SawTooth design came from the irregular shape of the leading edge of humpback whale pectoral fins.
Princeton Carbon Works is a relatively young US performance wheel brand that arrived on the scene in 2018, conceived by a group of engineering graduates from Princeton University.
Princeton’s Wake pattern is said to have taken four years of development, and what you are left with is a rim that contains 24 sinusoidal oscillations, giving a depth that varies from 60mm to 65mm.
"Advanced aerospace engineering facilitates better speed through the breakthrough of dynamic cross-section variability – WAKE – which yields lower drag and reduced effects of vortex shedding," says Princeton.
Stu Kerton recently reviewed Princeton’s Wake 6570 Disc Tune wheelset and his full review can be found here.
The depth of the Princeton rim and the Zipp rim each vary, but the Princeton undulations appear symmetrical while the shape of Zipp’s is more like a sawtooth.
SRAM complains that Princeton was aware of the SRAM patent and continued to market its wheels. SRAM is asking for tripled damages for willful infringement and for Princeton to be ordered to deliver up for destruction any remaining inventory, according to Bicycle Retailer.
Anna has been hooked on bikes ever since her youthful beginnings at Hillingdon Cycle Circuit. As an avid road and track racer, she reached the heady heights of a ProCyclingStats profile before leaving for university. Having now completed an MA in Multimedia Journalism, she’s hoping to add some (more successful) results. Although her greatest wish is for the broader acceptance of wearing funky cycling socks over the top of leg warmers.
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20 comments
I've heard a rumour that Apple are inventing the wheel soon, then we'll all be walking everywhere...
If I was wealthy enough I'd buy as many sets of the Princeton wheels as I could get my hands on and sell them on.
On the face of it SRAM/Zipp appear to be 'doing a Specialized', calling in the big guns simply because they can. I wonder if there has been any civil dialogue before they took this step.
(Specialized are well known for taking very aggressive steps to protect their IP, even when it's not their IP in the first place!)
Basically biomimicry. Whales have been using wavey edges on their flukes to improve hydrodynamics for thousands, if not millions of years. Surprised they haven't sued SRAM.
Well, they don't get out on land much!
I wonder if squirels have any wavey parts for aerodynamics?
Depends on their stylist
Ah but they never registered the patent... SRAM lawyers have already lined up a fleet of Chinese whaling boats and plan on taking blubber in compensation.
Hmm if they are different shaped wobbles Im not sure this is anything but bullying on the part of SRAM. Patent law is notoriously murky - especially in the US - it would be interesting to know where these SRAM patents are registered, if the US its entirely possible they are meritless, if in the UK there might be a bit more merit it them.
Looking at the patent (it's linked in the article under the reference to 'Metron IP') it's a US filing, so they're almost certainly bringing infringement proceedings in the US, although there are GB equivalent applications. The Claims of the patent are broad: Claim 1 is: "A wheel for use with a bicycle, the wheel comprising a hub about which the wheel is mountable to a bicycle, a rim about which a tyre is mountable, and a plurality of spokes that extend between the hub and the rim, wherein at least part of the rim has an undulating configuration having peaks and troughs."
Essentialy - The patent covers any bicycle wheel with an undulating inner rim. So...the fact that the wheel that SRAM/Zipp actually build is saw-toothed is irrelevant, and the fact that the Princeton one is explicitly 'sinusoidal' is also irrelevant.
The bigger problem facing SRAM is that the UK patent was filed in 2011, the US in 2012/13. The UK one has already expired and the US one will pretty soon. They might kill Princeton as a single company, but the basic concept of wavy-rimmed wheels will be free for all in a couple of years regardless. (Although there are almost certainly narrower patents now filed for specific patterns of saw-toothiness, sinusoidal-ness, probably even square-wheels, given the bike industries habit of just slapping a patent on it in case).
Undulating configuration, like a Mavic Ksyrium??
Brilliant - presumably "prior art" give its a rim brake rim, and another example of the not-fit-for-purposeness of the US patent industry.
My thoughts as soon as I read the article!
Interesting that Zipp/SRAM have had this patent for so long, but most of their wheels do not follow this design.
Is it significantly more expensive to produce?
There's only so many idiots willing to buy them
You are quoting claim 1 from the patent application, rather than the issued patents. Claim 1 of US patent number US9,610,800 (one of the issued patents) is narrower in scope and reads:
1. A wheel for use with a bicycle, the wheel comprising:
a hub for mounting the wheel to a bicycle;
a rim about which a tire is mountable; and
a plurality of spokes extending between the hub and the rim,
wherein the rim has a radially inner edge, and wherein at least part of the radially inner edge has an undulating configuration and a radial distance that continuously varies between adjacent peaks and troughs of the undulating configuration, each peak of the undulating configuration having a convex exterior profile in a plane of the wheel.
So there is some additional detail in there, to distinguish the invention from the "prior art" that was relied on during examination of the patent application.
US10,611,188 is the other issued US patent. I haven't read them in detail, but the claimed invention seems to be about convex peaks.
It's hard to make peaks that aren't convex. Concave peaks? Maybe flat and pointy?
It's also hard to have an "undulating configuration" of the inner edge where the radial distance doesn't vary.
And the distance "continuously varies between adjacent peaks" but only in the "at least part of the radially inner edge" that has the "undulating configuration" so it doesn't negate the possibility of flat spots.
To me, this patent claims any inner rim shape with multiple repeated non-pointy peaks.
I thought that too, but then reading the actual wording it says
Which sounds to me like it's bulging out sideways at each peak?
I'm an engineer, not a patent lawyer, but I don't find this clear at all. If I drew a wheel, I'd say that the peaks were "in the plane of the paper" which would be in the plane of the wheel. If the bumps extended into the Z axis, I'd say they were "out of the plane of the paper." I'd expect there would be a drawing in the patent to make this key detail clear if that's part of it.
It would also mean that Princeton is not infringing unless theirs bump out sideways too.
It does have lots of drawings, of lots of different configurations, including an outré one with four wobbly-edged spokes. It looks like it's basically trying to cover any use of undulating design anywhere on the wheel.
I don't think "convex peaks" would cover flattened undulations, which may be how the Mavic design is interpreted. The "at least part of the radially inner edge" means that "flattened troughs" would be covered, but the "convex peaks" feature is limiting.
It is normal for patent claims to be interpreted in the context of the detailed description - this can lead to surprising deviations from the literal or normal meaning of the words in the claim.
I see that EP patent well on the road to being granted and this will automatically cover the UK. The definition of the wheel shape being more mathematically defined than the granted (and in force) US patent.
EP Patent claims (that define the monopoly given by the patent) which seem to be allowed:
1. A wheel (1) for use with a bicycle, the wheel comprising a hub (4) about which the wheel is mountable to a bicycle, a rim (2) about which a tyre is mountable, and a plurality of spokes (3) that extend between the hub (4) and the rim (2), wherein the rim (2) has a radially inner edge (5) of the rim (2), and the rim has side surfaces (7, 8) that meet at the radially inner edge (5) of the rim (2) the side surfaces being configured such that the radially inner edge (5) is defined by inner portions of the side surfaces (7, 8), and at least part of the radially inner edge has an undulating configuration and a radial distance that continuously varies between peaks and troughs of the undulating configuration, each peak of the undulating configuration having a convex exterior profile in the plane of the wheel,
characterised in that the side surfaces (7, 8) are convex in form and the radially inner edge (5) forms a convex curve in a plane orthogonal to the plane of the wheel.