Hall Wheel Sensor Installation and Troubleshooting

Modified on Mon, 03 Jun 2024 at 04:04 PM

This guide relates to Carpe Iter Hall Effect Front Wheel Sensor. If you are using other front wheel sensor, please contact manufacturer for installation guidance. 

Sensor installation:

  1. Install the locking nut on the sensor screw, with the flange facing the end of the screw:         
  2. Screw the sensor into the brake caliper:   
  3. Make sure that the sensor screw is flush with the brake caliper. If it sticks out, then it might obstruct braking function and/or cause damage or get damaged by the magnet. Once flush, secure the sensor screw in place with the locking nut:

  4. Route the sensor cable along the brake hose. Make sure to tie the cable down:  

  5. Rotate the handlebars left and right. The sensor cable should not be getting pulled, and must not prevent full rotation of the handlebars. Make sure there is sufficient slack in the cable to prevent damage. Make sure the slack won’t interfere with normal operation of the motorcycle.

  6. Connect the sensor cable to the Terrain Command III, or the BMW Control Hub – the connectors on both controllers are compatible. Do not modify the connectors.


Magnet installation: 

If your brake disk is pre-drilled for magnet installation, please use a magnet with a circlip. We offer the 2 most common magnet sizes 9,5mm and 9mm. This is the recommended method.

If you cannot install a magnet into your brake disk, you can use the included magnets and glue them directly onto your brake disk or brake disk carrier plate, BUT this procedure is mentioned only as a life-hack and is to be taken at your own risk:

  1. Place one of the provided magnets onto the brake disk (brake disk carrier plate) – do NOT glue it in place yet.
  2. Make sure the center of the magnet is within 1cm of the center of the sensor screw. It is recommended for the magnet to directly face the sensor screw. If that is not possible due to your brake disk shape, there should be at least some overlap of the sensor screw over the magnet footprint. If the center off-set is too large, the sensor might not work reliably, because the magnetic field would be too weak for the sensor to register. Make sure the magnet is not touching any screw or other metal elements on the brake disk / disk carrier plate to avoid magnetising them. That could lead to the double-counting or having unreliable measurements.

  3. Rotate front wheel to make sure the magnet doesn’t hit the brake caliper, braking pads or the sensor screw – when you rotate the front wheel and the magnet stays in place, it is safe to assume that there is no obstruction. It is recommended to re-check several times. If the magnet moves out of place, relocate it to a different spot to prevent obstruction with other components on your front wheel (even 1mm shift might make a difference).

  4. Connect Terrain Command or BMW Control Hub to the Carpe Controller app, go to Settings and:
    1. Make sure “Enable Wheel Sensor” is selected:

    2. Go to Front Wheel calibration and start the auto-calibration procedure
    3. Spin the front wheel on your bike and make sure the Sensor count goes up. Make sure the sensor isn't double counting or skipping some rotations. If there is no increase in the count, adjust the magnet position to properly align with the sensor screw – go back to step 2 above. When you adjust the magnet position, step 3 also needs to be repeated.

  5. Once you find the final location for the magnet, mark the correct spot on the brake disk and remove the magnet

  6. Clean the area on the brake disk for magnet placement with flash solvent and sand it a little with fine grain sandpaper to ensure proper magnet adhesion

  7. Glue the magnet in place with high quality acrylate glue. Suggested procedure – place magnet on the tip of your index finger, put a drop of glue on the magnet, with the magnet still on your fingertip, place the magnet onto the brake disk. Push hard on the magnet to ensure best possible adhesion. If you didn’t get it right the first time, no worries, there is a spare magnet included with the sensor.
  8. After the glue cures, re-check the installation (step 3).

  9. Calibrate the Front Wheel sensor in the Controller app. Either automatic calibration, which requires riding the bike for a while – follow on screen instructions in the Controller app. Or you can enter front wheel circumference manually, if you know it. Please note that even small circumference deviations matter. Our sensor is really quite precise – it is recommended to re-calibrate the front wheel sensor several times during the lifetime of your front tire, as it wears down. It is particularly important when using non-FIM tires with higher knobs. The circumference change caused by tire wear can exceed 5%, which will effect the speed and distance readings considerably.

WARNING: Gluing magnet onto the brake disk might involve several hazards. The magnets we provide are very thin, but still there is a slight chance they might obstruct the correct braking function – you MUST test your brakes in a safe environment and at low speeds after installation. If you did not glue the magnet properly it might fly off or it can get chipped off by hitting an object (e.g. tree branch or a rock) when riding. The magnet fragments (or whole magnet) might get stuck inside your brake caliper or brake pads and negatively impact on the braking function. To minimize that risk, the provided magnet is really very thin and, therefore, it is very unlikely to create shards of such size in order to actually prevent braking. Also, neodymium magnet is quite brittle, which means that if it would really get stuck between the moving components of your braking system, it will be probably crushed to dust before it can actually negatively impact the braking force. Nonetheless, we emphasize that this type of installation is at your own risk. (P.S. we’ve been using that type of installation on our in-house KTM 690 Enduro R for many years ;-).)

Remember, the sensor only works when the controller is powered – it does NOT work reliably when the controller runs on the internal back-up power source. For the sensor output to be usable by apps, the Carpe Iter Controller app needs to be installed and Carpe Controller Accessibility service running.


  1. There is no Sensor count increment or increment is not reliable (sometimes a the count increases, sometimes not) when calibrating the sensor:

    1. Make sure the controller is connected to your Android device (e.g. CI Pad)

    2. Check that the controller is actually powered (depending on your setup and bike, you might need to start ignition or start engine)

    3. Check that the magnet is positioned correctly (see step 2 above)

  2. The sensor is double-counting (the sensor count increases by more than 1 per single wheel revolution):         

    1. Make sure the magnet is not touching any metal object (other than brake disk or brake disk carrier, if you decided to simply glue a magnet on there) – if it touches e.g. a brake disk mounting screw, secondary magnetic field is created around the screw and the sensor will be double-counting.

    2. If you use other than provided magnet, make sure the magnet diameter is not greater than 10mm. Use of other than circular magnets is not recommended.

    3. Make sure there is no second magnet on your front wheel, which would be circulating close to the sensor screw. Even a small shard of a magnet can be registered by the sensor in case the magnet broke or a small part of the magnet chipped off.

    4. If still no joy, try to increase distance between the sensor screw and the magnet. That can be achieved by relocating the magnet (if possible) or by screwing the sensor out a little (when looking at the sensor screw from the magnet side, the screw will sit deeper inside the brake caliper – it will no longer be flush with the caliper, but recessed).

  3. The distance seems off (other than for reasons above):

    1. Calibrate sensor (see step 9 above)



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