Axle mount pedal assist sensor installation and service

For VoltBike models: 

Bikes with hub motors using axle mounted pedal assist cadence sensors, mounted on the non-drive side of the bottom bracket axle.

Tools / parts required:

- Adjustable wrench / or 15mm and 17mm wrench

- Crank puller for square taper cranks

- 8mm hex key

- Cutters

- Zip ties

Introduction:

Most E-bikes with hub motors use an axle mounted cadence sensor that monitors the riders pedaling action. A pedaling motion of a half rotation of the cranks initiate a signal to activate the hub motor. Once the rider stops pedaling, the signal will be cut, and the motor will stop running.

The pedal assist cadence sensor works independently from the twist throttle and may come in two styles:

• axle mount on the non-drive side
• magnet disc with sensor on the drive side behind crankarm

 (see separate article in our help center)

Check your style before ordering spare parts. The two styles of pedal assist sensors are both compatible with most hub motor VoltBike as long as the plug connector colour and pin type are the same.

Troubleshooting:

If your pedal assist has stopped functioning, first determine whether the throttle is still working. If the throttle and other functions are working properly and only the pedal assist has stopped, then there may be an issue with your pedal assist cadence sensor. It may be the connector plug, bent pins, or how the unit is mounted on the axle.

An inconsistent signal to the motor may be due to dirt and contamination that is affecting the interface between the static and rotating part of the sensor causing the pedal assist and motor to randomly power on and off.

To replace or service the PAS sensor follow the below instructions.

1. Remove the battery, and hold the bike’s power button ‘on’ to discharge the controller. The screen may flash for one second and go out. The bike is now fully discharged.

2. Locate the pedal sensor’s cable and plug into the controller. Carefully cut any zip ties and gently wiggle and remove the sensor cable and plug from inside the frames downtube. Pull firmly to disconnect the plugs.

3. To replace the sensor the crankarm must be removed. Use an 8mm hex tool to first remove the crank bolt.

4. Next use a square taper crank puller and wrench to remove the crank arm from the bottom bracket axle.

5. With the non-drive side crank arm removed, gently wiggle the sensor body out of the bottom bracket cup splines and off the axle. Remove the unit to replace or clean.

Tip: The rotating inside part can be carefully snapped apart to clean and check for damage.

6. Once the sensor has been serviced or replaced, position the sensor over the axle with the cable at the bottom. Check the plastic splines are aligned with the bottom  bracket cup, then press firmly until the unit is fully seated.

7. Align the arrows and carefully connect the sensor plug to the controller plug.

8. Before reinstalling the left crank arm, insert the battery and turn the bike on. Set to PAS level 1 and slowly rotate the drive side crank forward one full turn to test the  new sensor and motor. The motor should engage.

CAUTION! Ensure the rear wheel is off the ground.

9. Once the pedal assist has been tested successfully, reinstall the LH crankarm and crank bolt. Use an 8mm hex tool to tighten the bolt to approx. 35-45 N*m

10. Carefully reinstall the pedal assist sensor cable and plug back up into the frame's downtown. Zip tie and secure any excess cables under the bottom bracket.

11. Test ride the bike for consistent motor power while riding and changing the various PAS levels 1-9.