OK, let’s just get this out of the way – NO, these are not wireless. No, they do not use electronic actuators to directly move the brake pads in or out. But YES, they do replace the mechanically operated piston in a hydraulic brake’s master cylinder with an electronically controlled actuator.

The real question is…why?

How Shimano’s electronic bicycle brakes work

shimano electric bicycle brakes for road bikes patent drawing concept

Rather, we should say, how they could work since this is, for now, merely a concept presented in a patent application.

Ever since the 2001 debut of Di2 electronic shifting, who hasn’t been curious about the possibilities of a completely fly-by-wire bike setup? Shimano’s Digital Integrated Intelligence (that’s where the Di2 comes from) already includes electronic shifting and suspension control, so why not add brakes, too?

The patent’s specific wording is “to provide a brake operating apparatus and a brake system that are capable of driving an existing brake apparatus by electric power.” And it specifically mentions that this is in lieu of using human power to drive that brake apparatus. That’ll become more important later…

shimano electronically controlled brakes for road bikes patent drawing concept

Which suggests that they’re not completely reinventing the brake, just the manner in which hydraulic brake fluid is pushed down the line to the calipers. Currently that’s handled by attaching a piston (or pushrod, plunger, whatever you want to call it) through a tube containing brake fluid.

As the O-ring seal on the end of that piston moves past a port, it closes the system and starts pushing brake fluid into the hose. That fluid moves to the caliper and fills in the space behind the brake pads, thus moving them closer to the brake rotor.

shimano electric bicycle brakes for road bikes patent drawing concept

To convert this into an electronically controlled system, Shimano presents a three-part design: A Detector, an electronic Controller, and an electronic Actuator.

The Detector detects brake lever movement and relays that information to the Controller. The Controller interprets that data and signals the Actuator to move the piston, thus pushing fluid into the brake line. Or pulling it back to release the brakes.

It’s all powered by a battery, which could be rechargeable by any normal means, including by an on-bike generator.

But why would we want electronic brakes?

Good question.

Patents aren’t required to answer why, just how. And from our reading of the application, Shimano doesn’t say why they would make this.

But we have some good guesses.

concept drawing for electronic brake levers from Shimano

Our concept drawing of what an electric brake lever could look like on a road bike.

First, the form factor of a brake lever could become anything you wanted it to be. You’d no longer need a large mechanical lever to “human power” those brakes. Instead, it could be a small trigger. Or even a button. Because if you don’t have to move the piston yourself, it doesn’t matter what size or shape device the signal is coming from.

Second, you could put multiple brake levers on the same bike. For triathletes and time trialists, this would be a game changer…no more repositioning your hands just to use the brakes.

 concept drawing for electronic bar top brake levers from Shimano

For roadies and gravel cyclists, you could easily have a small secondary brake lever on the tops of the bars, too. Or have small remote triggers that could be mounted on mini-aero extensions…wherever.

Third, for handcycles and other non-traditional bicycles or cyclists with different abilities, you could create much more ergonomic solutions.

Reliable execution is the hard part. Where you can accept that a dead Di2 battery might mean you have to ride home in a less-than-ideal gear combination, a brake failure from a dead battery or unplugged cable is not acceptable. That’s probably been the big obstacle until now. Yet plenty of people fly on planes where all the critical controls are only connected to the pilot by electronic links (hence: fly-by-wire), so maybe if robust enough system integrity is solved, we might see bicycles with electronic disc brakes.

And, yes, we suppose you could also make it wireless.


    • blahblah1233445 on

      ABS is fine, but what about the brake lever feel (no fluid pressure resistance), modulation etc…? Also – current levers are long not only for the better leverage, but also cause You need to reach them from both the hoods and drops.

      • Nigel on

        Yes the lever feel will be a problem. Unless that detector had another motor to produce some resistance based on the pressure. Seems unnecessarily complicated.

  1. dr_lha on

    Safety aspects of having electronic braking cannot be exaggerated. You don’t want that brake lever running out of power halfway down a huge descent.

  2. Dude on a bike on

    ABS. Bosch and Continental already have systems in place. This will be standard on E-Bike going forward of certain classes.

    This would be a great system and lighter than most mechanical ABS designs.

  3. Crash Bandicoot on

    Regarding dead batteries, you’d actually have to engineer the braking system to work backwards so that by default the pads are pressed on the rotor, (similar to air brakes) and the only way the brakes are deactivated is by the system running. As far as fly by wire? I don’t know, those systems have a variety of backup system for hydraulic, electric and computer, the parts are changed on a time based schedule, and the quality/Qc of parts would blow away anything in the automotive industry let alone the bicycle industry which is largely a joke in that regard.

    • Evan on

      If my battery dies in the middle of a twisty descent or fast paced peloton, I don’t think slamming on the brakes is much better than losing the brakes.

      • barael on

        It could probably achieved so that when the system detects the battery going out soon(ish), it would perform a controlled braking and then lock the pads pressed together until a decent level of charge was detected. With current battery technology that could mean your bike locking up with anything from 5% to 20% battery left so hardly ideal either, I guess.

  4. iiwas on

    My guess is that this patent is about non-linear (and probably customizable) engagement of the pistons relative to the movement of the break lever.

    One of the biggest problems with road disc is disc rub, caused by the tiny gap between brake pads and disc, which becomes an issue once the disc deforms because of heat, or misalignment after a wheel swap.
    If Shimano was to widen the gap between pads and disc, the first few degrees of lever movement would only move the pads through empty space, and it would take longer for them to engage the disc compared to todays setup.

    With an electronic system, Shimano could have more piston movement for the first few degrees of level movement, thus allowing a wider gap between discs and pads. Even customization of the engagement curve would be possible.

    • Florian on

      That was my guess, too. But you say it better in english than me: “vous m’ôtez les mots de la bouche! »

  5. Evan on

    I wonder if this is to allow integration of a regenerative braking system on ebikes. One lever, press a little, get regen, press more, get real braking.

    • ButtersWorth on

      Little bit of a niche use case considering most brands have gone to center-drive units. Regen only really works with a hub motor.

  6. DField on

    Cool if it had a cafe function so you could lock the wheels up while you went in to order a latte. Obviously it wouldn’t be as good as a lock, but it would stop a lot of the grab and ride thieves.

  7. blahblah1233445 on

    Still – it’s not the same as the direct feel. Check how loadcell brake pedals work in gaming driving wheels – there are hard springs generating resistance (with a small, soft one for some ‘dead zone’ at the beginning) and a pressure sensor. Yet everyone can tell, that it’s not the same as a true hydraulic brake.

  8. Mark Beilby on

    Another good reason for electronic brakes would be to make $5,000 from selling one group set. You just don’t get any profit from shimano 105.

    • Rod Diaz on

      I am not interested in the idea for bikes… but assuming you have driven a car designed and built in this millennium chances are you have experienced electrically-actuated brakes. And they can be made to have proper feel, etc.

      There’s a lot of other things to go around to make this viable and redundantly safe, but it’s hardly the first instance of such a system.


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