Introduction

The torque sesnor on some Biktrix eBikes is integrated into the bottom bracket of the bike. If this part fails replacement may be necessary to regain your pedal assist capabilities.


Tools required:
  • 8mm Allen Key
  • 15mm Flat Wrench
  • Crank Arm Puller
  • Bottom Bracket Removal Tool x 2
  • Ratchet/Breaker bar/adjustable wrench to attach Bottom Bracket Removal Tool to x 2
  • Large Adjustable Wrench x 2
  • Wire Hook
  • Wire Snips/Cutters for zip-ties
  • Replacement Zip Ties
  • Bike Parts Grease (Biktrix recommends Park Tool Polylube 1000 - #PPL-1)

Step 1

  • Remove the battery or Batteries from the bike. 
  • Discharge any excess electricity from the eBike by holding the POWER button on your display to turn on the display while there are no batteries connected to the bike.
  • Remove the chain from the chainring. To do this shift the bike to the largest gear. Push the derailleur forward. Then remove the chain from the chainring of the bike taking advantage of that slack.

Step 2

  • Use the 8mm Allen Key to remove the bolt holding the crank arm on the drive side of the eBike. 
  • Use the crank arm puller alongside the 15mm Flat Wrench to remove the crank arm.
  • Repeat this process on the non-drive side of the bike to remove the crank arm.

Step 3

  • Use the wire hook to remove the plastic cover off of the drive side bottom bracket to expose the threaded portion of the bottom bracket.
  • Unplug the torque sensor connector from the controller.
    • On bikes where the controller is mounted to the rear of the seat find the wire coming from the underside of the bottom bracket. You may need to snip some zip ties to free the wire to access this.
    • On the Juggernaut Hub Duo bikes you will need to remove the plate over the controller compartment to access this wire. The bolts can be removed with a 2.5mm Allen key - they are pictured in the third image here.

Step 4

  • Take your two bottom bracket removal tools and insert them into each side of the bottom bracket. 
  • Hold the removal tool still on the drive side of the bike. On the non-drive side of the bike slowly rotate the bottom bracket removal tool counterclockwise. 
  • While doing this hold the tool at the drive side of the bike steady - if not the wire from the torque sensor could shear off extremely easily!
  • You can now remove the non-drive side/left bowl bearing from the bike.
  • Slowly slide out the bottom bracket torque sensor from the bike, ensuring the wires on the bottom bracket remain stable.
    • The torque sensor wires are very thin and can break easily so be careful while doing this!
  • Use the bottom bracket removal tool to remove the right side bowl bearing. This is a good time to inspect it for damage and grease it to keep your bike moving smoothly!

Step 5

  • Take the right side/drive side bowl bearing and apply a light coating of grease to the bearing's threads along with the internal threads on the bottom bracket.
  • With your freshly greased drive side bowl bearing and thread it into the right/drive side of the frame by hand. Insert approximately 5 threads into the frame by hand - tightening counterclockwise as seen in the below image.
  • Once the bowl bearing is partially inserted into the frame use the Bottom Bracket tool to fully insert and tighten the bearing into place

Step 6

  • Take the Bottom Bracket Torque Sensor and stand on the Left/Non-Drive side of the frame.
  • Insert the Signal Wire coming from the torque sensor into the hole within the bottom bracket designed for the signal wire to go through - it may be on the top or bottom depending on your bike.
  • Slide the side of the torque sensor that has the directional indicator tape (see the second image for reference) into the bottom bracket slot of the bike.
  • Slowly insert the torque sensor while pulling the signal wire out from the hole while simultaneously pushing on the rubber surface of the bearing installed during the previous step.
Once the torque sensor is 1/4 of the way inserted into the frame advance to the next step.

Step 7

  • Examine the torque sensor for three marks as pictured. Align them according to the images attached to this step.
    • If the marks are not aligned with the images ie reversed please carefully remove the torque sensor and reinsert based on the instructions contained within the previous step with these parks oriented correctly.
  • Push in the torque sensor as far as possible by hand with no tools, ensuring the marks are still correctly oriented with wire in the correct place.

Step 8

  • Take the left/non-drive side bowl bearing and apply grease to the threads of the bearing as well as the internal bottom bracket threads.
  • Stand on the left - non-drive side of the frame. Insert the left side bowl bearing rotating it counter-clockwise by hand to insert as seen below. Insert this to 4 or 5 threads by hand - ensuring you do not cross thread the part while inserting it.
  • You now need two people to perform the next steps:
    • Person #1 will use one socket wrench with a bottom bracket tool on the left, non-drive side of the bike to slowly tighten the bearing into place.
    • Person #2 needs to hold the drive side end of the bottom bracket tight with a socket wrench and bottom bracket socket attachment or an adjustable wrench. Their job is to ensure the torque sensor assembly and signal wire do not rotate while Person 1 tightens the bearing.
Once the bearing is fully tightened check that the bottom bracket torque sensor wires are still intact and connected to the torque sensor.

Step 9

  • Plug the torque sensor connector back in and zip tie any excess wire to connect it to the rest of the wiring harness if applicable
  • Reinstall the crank arms, chainring and chain. 
  • Turn on the bike and check that your torque sensor is functioning by putting the bike in a high PAS level and applying force to the pedal while you have the rear wheel off of the ground. If the motor activates then you have successfully replaced the torque sensor.
  • If the torque sensor is not working:
    • Ensure the torque sensor wire is plugged in
    • Ensure the sensor wires did not break during the installation process.