What is an eBike Brake Sensor

What is an Ebike Brake Sensor and How Does it Work

The thrill of effortlessly going fast on an eBike needs to be harnessed with the confidence of being able to stop.  Image comfortable cruising along enjoy the scenery and a car pulls out and…..  An eBike adds more power than a person can generate on their own to moving the bike.  In a panic situation the power to the wheels needs to be cut as quickly as possible.

This is where eBike brake sensors step in to help improve stopping distance.

How does an eBike brake sensor work
How does an eBike brake sensor work – a small switch sends a signal to controller

How Does an eBike Brake Sensor Work

Ebike brake sensors cut power to the motor the moment the brake levers are actuated.  The sensor sends a signal to the speed control overriding the power when either the pedal assist or throttle is being used. The brake sensor does not change how the bike brakes work, it only cuts power to the motor.

Can Brake Sensors Work on Bikes with Hydraulic Brakes?

Yes, the braking signal comes from a proximity switch using a “reed switch” or proximity switch and magnet.  The magnet is applied to the brake lever and the reed switch to the brake handle housing.  As the brake handle is depressed the reed switch moves sending a signal to the speed controller cutting the power to the motor. Sourcehttps://www.sciencedirect.com/topics/computer-science/magnetic-switch

It is possible to buy hydraulic brake handle assemblies with the brake sensor engineered into the handle housing.  These are a little more complicated to install because you need to have the skills to cut the hydraulic brake houses and bleed the hydraulic brakes.  Here’s a resource for learning to bleed hydraulic brakes. https://www.diymountainbike.com/when-bleed-mountain-bike-brakes/

Retro-Fit eBike Brake Sensor
Retro-Fit eBike Brake Sensor used for hydraulic brakes

How do You install an Ebike Brake Sensor

For bikes with v-brakes  the sensor is built into the brake lever housing on the handlebars.  The installation is as simple changing the old brake levers with brake levers with the sensor switch built in.

Install eBike brake with sensor
Install eBike brake with sensor

Process for installing eBike brake sensors

  1. Remove handlebar grips.
  2. Remove shifters.
  3. Disconnect brake cable at wheel, this releases the tension on the brake cable.
  4. On the brake handle housing align the barrel adjuster slot, locking nut slot and housing body slot and squeeze brake.
  5. With the brake depressed, rotate the brake cable out of the brake handle assembly.
  6. With the cable removed from the housing, loosen the brake handle assembly from the handlebars.
  7. Remove brake handle assembly from handlebars and install new brake assembly with brake sensor.
  8. Finally, connect the brake wires to the eBike wire harness.

Tools needed for install eBike Brake Sensor

Just a handful of tools are needed, all of which are usually found on a bike specific multi-tool set. 

Multi-Tool for Bike
Multi-Tool for Bike – my favorite is the Crank Bros M19

The one tricky item to remove is usually the hand grips that can get stuck on to the handlebars.  A trick for removing these is using a little bit of rubbing alcohol under the grip.  Don’t use lubricates because when re-installing the grips won’t grip anymore. 

  • 4mm Hex wrench for locking grips
  • 5mm Hex wrench for shifter
  • 6mm Hex for brake housing
  • Possibly a Phillips screwdriver for brake cable
  • 10mm wrench for brake cable removal

Adjusting an Ebike Brake Sensor

If you’re using an eBike specific brake handle with sensor, you really shouldn’t need to adjust anything other than how the brake handle feels by rolling the brake housing on the handlebars. 

If you’re retro-fitting a brake handle system with a brake sensor the installation is a little more complicated and may need adjustments.  The distance from the magnet to switch is important.  Start by temporarily positioning the switch on the housing using zip ties.  Then position the magnet on the brake handle adjacent to the switch.  Adjust the magnet position until the motor power is “cut-off” when the brake is applied.

Trip Wire Brake Sensor
Trip Wire Brake Sensor – image credit Grin Tech – link

Another option is a Trip Wire method using the Grin Tech Trip Wire.  The Trip Wire adds the sensor by attaching a linear pull switch to the brake handle.   The Grin Trip Wire can be adjusted by re-positioning the cable housing on the brake housing and brake cable.

Testing an eBike Brake Sensor

The best wat to test the sensor is to complete the installation and try it out.  I’ve found using a bike repair stand is perfect for this.  It allows the bike to held steady with the wheels off the ground.

With the power tire allowed to spin freely, gently apply pressure to the throttle to get the tire moving at a constant rpm.  WHILE THE TIRE IS POWERED, APPLY THE BRAKE.  If the motor stops your brake sensor is working.  This test must work regardless of whether the front or rear brakes are applied.

Troubleshooting eBike Brake Sensors?

Since the motor will function without brake sensors the most common problem is a loose or pinched wire or connection.  Thoroughly inspect the wire routing looking for pinch points and re-install any connections.

Another error can happen when the proximity switch falls off the brake handle housing.  If this happens the switch will send a signal that the bike brakes are being constantly applied.

How Much Do eBike Brake Sensors Cost?

With the price of dedicated brake handles engineered to use a brake sensor nearly the same price as a retro-fit kit, I would recommend the eBike Brake Sensors designed for the function.  Having highly functional brakes designed to cut the power and stop your bike is the best of both worlds.

Brake Sensors Designed into BrakesPriceLink to Product on Amazon
Cable eBike Brake Sensor$18.99https://www.amazon.com/Brakes-Durable-Bicycle-Electric-Replacement/dp/B07DR9S5C9
Hydraulic eBike Brake Sensor$89.00https://www.amazon.com/Accolmile-Hydraulic-Electric-Rotors-BAFANG/dp/B0838X8GCC
Retro-Fit eBike Brake SensorsPriceLink to Amazon or other
Hydraulic and Cable eBike Brake Sensor$18.00https://www.amazon.com/Sensor-Hydraulic-Mechanical-Electric-Bicycle/dp/B08N612XYH
Grin Tech Trip Wire$39.00https://ebikes.ca/shop/electric-bicycle-parts/ebrakes/tripwire-pull.html

How Do You Fix an eBike Brake Sensor?

Most problems occur when a component of the brake system becomes lose.  This might be a wire connection or a loose proximity switch.  The best fix is to re-attach the wires or switch. 

Sometimes the wires can get damaged, if you’re handy with a soldering gun you can re-connect. But be sure to test and find out why the wire was damaged.

Are eBike Brake Sensors Needed?

There are no “laws” saying eBike are required to have brake sensors and an eBike will work without brake sensors.

I would suggest that having brake sensors is a good thing though.  They don’t slow your bike when NOT in use.  With the increased weight of an eBike along with the power being applied by the motor, cutting the power while braking just makes senses.

You can try your ebike without them, by disconnecting the wires and decide for yourself.

FAQ

My eBike Doesn’t Stop What’s Wrong?

An eBike Sensor only cuts the power to the motor, it doesn’t stop the bike.  Take a deep dive into the actual bike brake system (cable or hydraulic) the brakes need to be adjusted or the hydraulic brakes might need to be bleed.  Here’s an article describing how to adjust the brakes

Can Brake Sensors Help When Shifting Gears?

Yes, especially on mid-drive motor kits.  Damage can occur to the chain, and rear cogs (often called gears) if power is applied while shifting.  A best practice is to stop applying pressure to the chain and drivetrain when shifting.  Lightly applying the brakes will cut power to the drivetrain making it easier to shift.

Banfang M625 Mid Drive Ebike Conversion Kit
BANFANG Mid-Drive ebike Conversion Kit image Amazon

Did you Know You Can Convert a Regular MTB to Electric?

Banfang a leader in DIY electric bike conversions has a mid-drive kit that will fit on most regular bikes. I’d recommend the M625 kit, it’s built as a complete setup with a huge capacity battery and a 1000 watt motor. Why this setup?

  • Heavy duty 1000 watt motor (built for cargo bikes)
  • +50 volt 19.6 Ah battery will provide speed and distance
  • Programmable bluetooth app to “unlock” the speed
  • Easy installation with provided tools.

If you’re considering a conversion, do what I’m doing get the BANFANG M625


David Humphries

Hi David Humphries here the guy doing all the pedaling behind the scenes with this blog. I’ve been in the MTB world for a while and recently started getting into eMTBs. You can check out more about me HERE and on my other passion project – DIYMountainBike.com