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Operating Device [Battery-less, Wireless Shifter] by Shimano

In this article, we’ll be discussing an Operating Device by Shimano, US publication 20210371035 and 20210371044. The publication date is Dec. 2nd, 2021 and the filing date is May 27th, 2020. These patents are not granted, but both pertain to the same design.  

Brief Summary (tl;dr)

Shimano are developing a new wireless shifter system, which appears to be exclusively for mountain bikes (in this case). The shifter should work fairly similarly to any current shifter, with two levers controlling two different functions – upshift and downshift. But, this can also adjust a seat post. The interesting part here is the shifter doesn’t contain any batteries, yet they’re wireless and electronic. Shimano are doing this by using a piezoelectric element behind a switch inside the shifter. So, when the rider pushes the lever, the switch and wireless transmitter are electrified/signaled by the applied stress to the piezo-element. As a result, the shifter wirelessly sends a signal to a controller to shift the derailleur.

Intro

It’s no secret that Shimano are working on a wireless system, similar to SRAM’s AXS. Whether they release it this decade is another story. I honestly thought the 100-year celebration would have been the release day, but they released a book instead… I’ll give them the benefit of the doubt that the 100-year announcement may have been reserved for a wireless system, but shutdowns and all that shit delayed the release.

I’ve written quite a few articles about electronic Shimano stuff; from droppers to a gaming bike, and even a fucking LIDAR system. Let’s not forget the machine learning bike, either. I’ve also written about their incoming wireless shifters, but we’ve never really gotten a good idea of what they may look like or how they’ll actually work. Shimano are extremely good (the best in the bike industry) about developing a well-rounded IP portfolio. As a result, we get to see things in pieces, rather than one document for an entire idea. This time, we’ve got a pretty good look on one idea we may see in the near future.

Why

From a high-level perspective, Shimano are just doing what they should be doing. The world is going electric and bikes are following suit. SRAM has proven the idea has some level of demand, and they’re probably making some decent money. Shimano wouldn’t be doing their business properly if they were ignoring electricity in bikes.

From a low-level perceptive, idfk. I never know why Shimano do anything. But, I will say it’s probably because they consider batteries to be a nuisance. I’ve seen a lot of well-founded complaints about bikes becoming too electrified, and having way too many batteries. Have you seen the new Trek Rail? It’s got a shit load of batteries for the shifter, Derailleur, shocks, tires, and motor. No thanks.

What

Like I said at the beginning of this article, this actually relates to two different documents. Both of which are nearly identical, other than the claims. Companies will do this because they believe there is more than one novelty within the same design.

FIGs. 3 and 9 show how this system works. In short levers 41 ad 42 share a pivot axis P1. Lever 42 sits behind lever 41. I’m going to assume one is for upshifting and one is downshifting. The operating unit 20 houses the switches and wireless communicator. You would push the levers, like any other shifting device, and the switch would send a signal to change gears or do whatever it’s programmed to do. Pretty self-explanatory.

But I’m over here trying to figure out what’s so special about this system and it finally dawned on me. Who gives a shit about a wireless shifter these days? Well, FIG. 2 (below) shows a block diagram of the components inside both the operating device (shifter) and the control unit (computer). The controller includes everything a controller needs to operate: processor, memory, battery, and a wireless communicator to talk to the shifters and derailleur. It is not located inside the shifter itself, but will be elsewhere on the bike. ED1 and ED2 are the derailleurs or seat post (probably derailleurs). Notice how they can be both wired (arrow) and wireless (lightning bolt).

This is where, in my opinion, this design gets special. Do you see a battery inside the operating device (shifter)? The answer is no, there is no battery. How the fuck are they running an electric and wireless shifter without a battery?

For simplicities sake, let’s just focus on 54 and 62 in FIG. 11, below; 56 and 64 will work exactly the same. First electric switch 54 includes, what Shimano are calling, a first electricity-generating element 62. You read that right, an electricity-generating element, which is a piezoelectric element that sits behind the switch 54.

…the first electricity-generating element 62 is a piezoelectric element provided in the first electric switch 54 such that the first electricity generating element 62 generates electricity in response movement of the movable part

While FIG. 11 is a pretty crude representation of the design, and Shimano don’t go too deep into the specifics, my interpretation is that when you press the lever, the spring 68 depresses enough to coil-bind, which applies a force to the switch 54. As a result, a force is also applied to the piezo-element, which then supplies a small amount of electricity (signal) to the switch and the wireless communicator, which sends a shift signal to the controller, which sends the shift signal to the derailleur, and the derailleur shifts. There it is in a nutshell.

A piezoelectric element is a material that creates electricity as a result of mechanical stress. These have been used for a while in the bike industry. In particular, the K2 SmartShock had a piezo material for active suspension. General uses would include sensors, motors, or actuators. It’s a pretty cool little material.

This is a little surprising to me, because I always assumed a piezoelectric device produces extremely small amounts of electricity. But, in this configuration, Shimano are saying that the piezoelectric electricity is enough to:

….provide electricity to the first electric switch 54 and the wireless communicator 60 upon activation of the first electric switch 54.

So, the piezoelectric element has enough power to actually send a wireless signal to the controller. I’ll be the first to tell you that I don’t know enough about piezoelectric stuff, and how much power they can actually make, but I’m still surprised. Maybe this is a situation where they’ve developed/found a wireless transmitter that takes next to zero power to operate. But, at lawyers do, Shimano also say the shifters can use a battery, just to cover their bases.

Here’s some background: this is an example shifter from another Shimano document, just for comparison. Notice the Power Supply B and B’. This is a more traditional configuration of an electric shifter that’ll be powered by some kind of power source.

Conclusion

Well, Shimano to the rescue. They’re developing a shifting system that doesn’t need a battery. And if you’re thinking ‘well, the controller still needs a battery’, then I’d need to remind you that the controller can be attached to the motor battery or be inside the motor battery itself.

The largest issue I see here is the degradation of the piezo-element. This document (P Pillatsch et al 2014 J. Phys.: Conf. Ser. 557 012129) suggests piezoelectric devices have some level of degradation over time. There are also numerous other research studies on the subject (Google Scholar). So, how do you change the piezo-element? Or do you change it? Is the shifter trash when it doesn’t produce electricity? Do you have to send it back to Shimano for a new one? Idk the answer to any of these, but it’s clearly the weak-link. That being said, if this does ever make it to market, it’ll be hella cool.

Lastly, Shimano’s legal writers/attorneys/engineers/whoever do such a great job with these. From a story-telling perspective, they’re not a lot of fun to read or write about. But, from a legal and technical perspective, they’re pretty damn good.

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