In this article, we’ll be discussing a Rear Derailleur by Shimano, US publications 202202004134 and 20220204135. The publication date is June 30th, 2022 and the filing date is Dec. 21st, 2021. These are not granted yet.
This is a excellently juicy example of the games being played behind the scenes in the bike industry (and every other industry).
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Brief Summary (tl;dr)
Shimano are attempting to protect a coaxial rear derailleur hanger that uses a B-screw adjustment. The derailleur looks awfully similar to the SRAM coaxial derailleur that I’ve talked about before, and has been seen at some races.
A few years ago, the USPTO released a document showing a new derailleur from SRAM. From a high level, SRAM’s derailleur is coaxial, meaning the hanger and axle share an axis (co-axis). This should be much stronger than a traditional hanger when it gets it, but should also be much stiffer for large cassettes. Que the “bUt MuH $15 hAnGeR!”.
An important aspect of this new derailleur, shown top left, is the lack of a B-screw. For those that don’t know, the B-screw is the screw on the back of the derailleur that controls the fixed position of the derailleur circumferentially about the derailleur pivot, shown top right. SRAM don’t need a B-screw due to their use of a set of ‘stop’s and ‘pins’. I show this later on in this article.
SRAM 16/950,282: The rotation prevention action replaces the conventional B-screw and protects against undesired forward rotation of the gear shift mechanism.
One of the documents is trying to protect the B-screw at a particular point in space relative to the hanger, and the other is trying to protect a coaxial hanger that can attach to a coaxial derailleur and a traditional derailleur.
It’s important to note that I can’t tell if this is what’s being used on SRAM’s actual bike – we’re just going to talk about what are in these documents.
FIG. 6 shows the overall design of this derailleur—Shimano left, SRAM right. Coincidence?
This is a cross-section of the hanger and axle. Shimano’s document on the left, SRAM’s on the right… A nut 60 goes into the hanger and the axle threads into the internal threads of the nut.
So, what are Shimano actually trying to do? Like I said before, SRAM doesn’t have a B-screw in their design, so Shimano show a B-screw, which is the attempted novelty of the ‘135 document, shown below. The B-screw makes contact with surface 20A on the rear triangle, and the rear derailleur adjusts. That’s about it.
Remember those ‘stops’ I talked about earlier? Shimano left, SRAM right. The stops are 84A/B in Shimano and 68A/B in SRAM. These things butt up against each other (radially about the axle axis) and provide a maximum amount of rotation, so it doesn’t rotate after installation. But Shimano added a B-screw 56. I mean, c’mon…
So, they’re basically taking an extremely similar design (won’t say exact design) and adding a B-screw. Well, there may be some issues with that. First, Shimano are probably going to contend with (at least) a 103 rejection from the USPTO, which states “this + this is not novel because it’s obvious to put them together”, also known as ‘motivation to combine’. For example, SRAM’s coaxial derailleur exists, B-screws have existed forever, and combining the two isn’t novel. But, a good attorney can overcome this.
Second, SRAM aren’t fucking stupid. They saw this coming from a mile away. They have access to counsel and generally smart people that prepare for shit like this. SRAM filed this document showing a number of B-screw options with a coaxial derailleur. They’ve basically said through a series of patents “We don’t need a B-screw, but we’re going to file B-screw designs anyway, based on our design, in case we need to use them in the future and we don’t want to deal with someone else’s patents”.
Alright, let’s talk about timing.
A priority date is the earliest filing in a family of applications, regardless of country of filing. SRAM’s earliest priority date (for the coaxial derailleur + B-screw) was March 22nd, 2019 (Germany) and the earliest publication was Sept. 23rd, 2020. I can’t find an IDS showing known similar prior art, suggesting SRAM doesn’t know of anything similar prior to their idea, but I could always be missing something.
According to this Shimano patent, they have a priority date of Dec. 31st, 2020, meaning Shimano’s was filed about 3 months after SRAM’s was published; so, Shimano had 3 months to see it (not claiming they did).
In the end, it appears SRAM filed first, their patent was publicly released, then Shimano filed these two documents with a B-screw.
Below show three examples of B-screw designs from SRAM. These two show a B-screw that abuts against the rear triangle in different spots. 307 and 507
This design shows a hinged hanger with a B-screw that adjusts the hinge opening.
Shimano also have a second document that was filed/released at the same time, where they’re defining a coaxial derailleur hanger than appears to allow a coaxial and traditional hanger to be attached. FIG. 12 shows a shitty cross-section of the hanger. The two top plates straddle the rear triangle and the bottom hole is used to mount a coaxial derailleur, shown in FIG. 13. A regular hanger can also be used, shown in FIG. 19.
There’s also an adjustment tool that Shimano threw into this application. Check out paragraphs [0102-0105]. I think this is out there, somewhere.
Now, I want to make it clear that I’m not saying Shimano won’t get this thing granted. It’s entirely possibly that they can still get it through, which could prevent SRAM from adding a B-screw in this exactly claimed design; even though SRAM have their own B-screw designs. What I’m saying is: SRAM have made this very difficult for Shimano to get this through the USPTO and SRAM appear to have defended their business interests well.
At the end of the day, Shimano can’t really prevent SRAM from using a B-screw, since they’ve already filed a few options they can use. But, if this is granted, they can prevent SRAM from using a B-screw in the exact fashion they end up claiming (assuming it’s granted at some point).
Maybe SRAM did something to piss Shimano off enough to do something like this? I don’t know their detailed legal history, but that’s always possible. I’d be very surprised if SRAM weren’t already working to invalidate Shimano’s idea with whatever legal magic they can come up with.
I had a lot more written in this section about how I feel about this, but I took it out. No one gives a shit about my opinion, and I don’t want to sway anyone either way. I just want to report what I see and let the public decide.