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eBrakes 101

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    eBrakes 101


    E-Brake is the name given to the piece of equipment that can sense when the rider has applied the brakes.
    That's all. It's worth noting why I limited the description to th
    at one specific function as you will see below.

    Do I need to have eBrakes?
    (The following is my personal opinion and does not reflect any position or recommendation by Luna Cycles)
    Most ebike controllers including the Bafang BBSXX do not require ebrakes to you could ride your bike without ebrakes. IF you do this be sure that your brakes are strong enough to stop the bike if the motor does happen to get stuck in wide open throttle mode (a rare but possible scenario).

    Are ebrakes a good idea?

    The short answer is yes.
    Depending on the programming of your system, the motor can pull after you stop pedaling albeit for a very brief time. In a sphincter clenching panic stop a brief time can seem forever. Lower power systems say <500w , the brakes can likely overpower the motor once you get to 750+ it's not so cut and dry. If you have a Cyclone 3000w + system then running without the extra safety of the cut off is just plain nuts IMHO.

    How they work

    E-Brakes is a misnomer in many ways but if we named it properly it would be the "Motor Current Cutoff Signal Sending Brake Lever Switch" or MCCSSBLS, hmm don't work as an acronym either.

    The E-brake levers are nothing more than regular brake levers that have an additional part added, that being a switch to sense when the lever is at its normal resting position or is being actuated by the rider. It is important to know how this system works, it's part of your brakes after all.

    The e-brakes are often called cut out switches and the overall effect is exactly that, the motor cuts off. The e-brake switch does not actually cut power to make this happen , what it does is it makes a connection and sends power to the controller , just the opposite of what "cutoff switch" implies.

    That flies in the face of normal "fail safe" design methods where if something were to damage the ebrake circuit the condition would be "no signal being sent" and hence trigger a motor cut off. The way these are currently configured if your e-brake wire gets cut your motor will still work. This is so folks that do not want to run them can just leave them off and have things still work. It can be argued that having your motor cut out unexpectedly could be dangerous as well. This is not really a safety issue since if you were to grab your brakes and the motor kept pulling, it is hoped you would stop peddling or let go of the throttle in self preservation. If you still have the motor pulling then the e-brakes were not your biggest problem to begin with !


    On most cable brake systems this is just a simple microswitch. The motion of the cable from its resting position closes a circuit in the switch sending power to the controller on a specific wire that the controller knows is the "STOP!" signal. The controller then cuts the current to the motor for you.

    Hydraulic brakes use a different system and it is also used to retrofit non-ebike brake levers without built in microswitches. This method uses what is called a reed switch or a magnetic proximity sensor. These work by sensing a magnetic field and opening and closing a switch accordingly. By mounting the sensor on the body of the brake lever and putting a magnet on the moving part of the lever we can manipulate the switch to behave like the physical switch on cable systems.


    Installing purpose built e-brake levers (cable or hydraulic) like the cable system levers that come with the BBSxx kits is the same as any other bicycle brake lever with the additional step of plugging in the sensors.

    Installation for non-purpose built levers is still very simple. Install the levers as you normally would,then affix the sensor near the pivot of the handle and position the magnet across the gap on the lever itself so that it moves away from the sensor when the lever is pulled. Plug in the sensors and you are done.

    This is a standard cable brake Bafang eBrake lever with connector, you can find these in the Bafang Parts section of the Luna site.
    . Click image for larger version  Name:	ebrake.png Views:	1 Size:	80.9 KB ID:	16022

    The full hydraulic version for Shimano compatible systems can be found here.
    . Click image for larger version  Name:	hydraulickit.png Views:	1 Size:	115.7 KB ID:	16023
    Last edited by Bicycle365; 07-03-2019, 08:41 AM.

    Once you've decided that yes, e-bike brake-handles with motor cut-off switches are a good idea, you may wish to have a brake-light circuit.

    Sadly, there's not enough milliamps available in that ultra-low-power e-brake cut-off signal circuit--but don't worry.

    A five-dollar relay (shipped) and a few minutes soldering time--and you're in business:

    Best of luck with your projects, everyone!