Were is the best place to mount the sensor and magnet on your hydraulics brake levers and how to do it on the first try?
Link to the Bafang sensors
There are way too many models to show you all, but I taken the 3 most popular ones:
This is what you receive: a magnet and sensor with double sided tape on it :
This sensor is a simple piece of hardware, there are no moving parts in it, it's just a reed switch (or hall sensor) potted in the plastic case. Basically when the magnet is close to the sensor the circuit is open and the controller lets power pass through the motor. Then when you pull the magnet further away from the sensor, the switch closes the circuit and send voltage to the controller then it instantly cuts the power to the motor.
For the installation procedure, I used the Shimano SLX version, but it's the same for all the lever, look down on the thread to your model to give you an idea were to start.
Also, the distance between the sensor and magnet shown in these photos is not the real one and it depends on the sensor and magnets, some will need to be closer together!
Sorry for my used sensor, I had to remove the glue around the magnet to do this post.
So before you epoxy everything in place and next figure out that it's not working properly, follow the next steps:
Clean the lever and base with alcohol to remove any trace of oils and dirt.
You want it to be sensible, to actually stop the motor before your callipers start to bite hard, but not too sensible that vibrations and just finger resting on the lever triggers the sensor.
I suggest to use a bike stand or find a way to lift the back wheel so it can spin freely while you work on the levers.
Plug on sensor in the yellow plug on your main harness. turn on the LCD.
Place the magnet at the most logical place on the lever (Again look down to other model to give you an idea)
If your don't have steel in the lever, use gum, tape, anything temporary to test the magnet.
What I do it use a clamp to set the desired level of lever action I want (like this next picture). place the sensor at the appropriate place closer to the magnet (do not remove the tape yet), give a little throttle and move the sensor away from the magnet till the motor stops. Remove the plastic and stick the sensor at the exact place the motor stopped. next remove the clamp (or whatever you used) to let go the lever.
Test again with a little throttle, actuate the lever, the motor will stop exactly were you wanted.
If it satisfies your needs, you can fix it permanently. I ride in wild trails and get hit by branches all the time, so I used good quality hot glue around the sensor and on the magnet, epoxy glue can be used too at your own risks! But I do not recommend to drill a hole in your lever and screw the magnet in place. Yes there is a hole in the magnet but it's really fragile and will crack with minimal pressure... better to use epoxy then it you tell want it solid! If you cracke the magnet, get some on eBay, look for neodymium magnets (do not use cheap black fridge ceramic magnet, it won't work)
Repeat for the other side, unplug the battery, plug the brake sensor....follow the steps!
Now the other models:
The Shimano M355 can be mounted 2 ways,
Front mount (Best), like the Shimano SLX. The double sided tape won't hold it enough, not enough contact surface, you will need use hot glue (or epoxy)

Underside installation, cleaner but harder to set properly. The double sided tape won't hold it enough, not enough contact surface, you will need use hot glue (or epoxy)
Link to the Bafang sensors
There are way too many models to show you all, but I taken the 3 most popular ones:
- The new Shimano series have a very similar lever. Shimano Deore (M615 and M506), the Shimano SLX (M675 M7000), the Shimano XT (M8000 and M785), the Shimano XTR (M90XX), The Shimano ZEE (M640) and the Shimano Saint (M820)
- The Shimano M355 (same as M396 and Acera)
- The Avid series (Elixir, CODES, BDx and juicy) Sram is now the new brand but the lever mechanism is similar.
This is what you receive: a magnet and sensor with double sided tape on it :
This sensor is a simple piece of hardware, there are no moving parts in it, it's just a reed switch (or hall sensor) potted in the plastic case. Basically when the magnet is close to the sensor the circuit is open and the controller lets power pass through the motor. Then when you pull the magnet further away from the sensor, the switch closes the circuit and send voltage to the controller then it instantly cuts the power to the motor.
For the installation procedure, I used the Shimano SLX version, but it's the same for all the lever, look down on the thread to your model to give you an idea were to start.
Also, the distance between the sensor and magnet shown in these photos is not the real one and it depends on the sensor and magnets, some will need to be closer together!
Sorry for my used sensor, I had to remove the glue around the magnet to do this post.
So before you epoxy everything in place and next figure out that it's not working properly, follow the next steps:
Clean the lever and base with alcohol to remove any trace of oils and dirt.
You want it to be sensible, to actually stop the motor before your callipers start to bite hard, but not too sensible that vibrations and just finger resting on the lever triggers the sensor.
I suggest to use a bike stand or find a way to lift the back wheel so it can spin freely while you work on the levers.
Plug on sensor in the yellow plug on your main harness. turn on the LCD.
Place the magnet at the most logical place on the lever (Again look down to other model to give you an idea)
If your don't have steel in the lever, use gum, tape, anything temporary to test the magnet.
What I do it use a clamp to set the desired level of lever action I want (like this next picture). place the sensor at the appropriate place closer to the magnet (do not remove the tape yet), give a little throttle and move the sensor away from the magnet till the motor stops. Remove the plastic and stick the sensor at the exact place the motor stopped. next remove the clamp (or whatever you used) to let go the lever.
Test again with a little throttle, actuate the lever, the motor will stop exactly were you wanted.
If it satisfies your needs, you can fix it permanently. I ride in wild trails and get hit by branches all the time, so I used good quality hot glue around the sensor and on the magnet, epoxy glue can be used too at your own risks! But I do not recommend to drill a hole in your lever and screw the magnet in place. Yes there is a hole in the magnet but it's really fragile and will crack with minimal pressure... better to use epoxy then it you tell want it solid! If you cracke the magnet, get some on eBay, look for neodymium magnets (do not use cheap black fridge ceramic magnet, it won't work)
Repeat for the other side, unplug the battery, plug the brake sensor....follow the steps!
Now the other models:
The Shimano M355 can be mounted 2 ways,
Front mount (Best), like the Shimano SLX. The double sided tape won't hold it enough, not enough contact surface, you will need use hot glue (or epoxy)
Underside installation, cleaner but harder to set properly. The double sided tape won't hold it enough, not enough contact surface, you will need use hot glue (or epoxy)
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