Pedal assist is not working: pedal sensor, brakes and cables
By the Sache Bikes workshop · updated 17-10-2026
If your fatbike's pedal assist isn't working even though the display turns on, the cause is usually a stuck brake sensor, a misaligned or damaged magnetic ring, or a faulty pedal sensor or extension cable. First, check the assist level and brake levers, then the sensor and cable at the pedal crank. Repairs can be carried out in The Hague and Zoetermeer, often on the same day.
In short
- If the display is set to assist level 0, the motor will not provide any assistance.
- A brake sensor that continues to send the 'braking' signal will switch off the motor.
- The pedal sensor reads a magnetic ring at the pedal crank; if it is crooked, dirty, or too far away, there will be no assistance or the assistance will be jerky.
- The pedal sensor's extension cable runs low along the frame and can easily be damaged.
- Replacing a pedal sensor costs €60, and the extension cable costs €45 (estimated price incl. installation).
Most common causes
The assist level is set to 0
It may seem too simple, but some displays start at level 0 after being switched on, or you may have accidentally switched it back. Press the plus button and see if the level on the screen changes.
A brake sensor is stuck
The brake levers on a fatbike contain a sensor that switches off the motor as soon as you brake. If a lever is slightly pinched, the sensor is broken, or the connector has become wet, the controller will think you are continuously braking. The display will still work, but the motor will do nothing. Sometimes you will see a brake symbol on the display. We replace a faulty sensor separately or together with the brake lever.
The magnetic ring is crooked or damaged
The pedal sensor works with a ring or disc containing small magnets, usually behind the left crank. With every pedal stroke, the sensor counts the magnets and sends the 'pedalling' signal. If the ring has shifted after a fall or work on the pedal crank, is torn, or is too far from the sensor, the assistance will not work, will be delayed, or will be jerky.
The pedal sensor itself is faulty
If the brakes and magnetic ring are in order, the pedal sensor may be broken. This can be caused by moisture, a blow to the sensor, or wear and tear. When replacing it, make sure you use the correct type and connector for your fatbike.
The extension cable is damaged
Many fatbikes have a separate extension cable running from the pedal sensor to the wiring harness. It runs low along the frame and pedal crank and can be rubbed through, kinked, or come loose when parking in a bike rack. Cables can be found under wiring harnesses and cables.
Controller or wiring harness
If the walk assist or throttle lever also does not work, the problem is more likely further into the system: in the wiring harness, the motor cable, or the controller. If the walk assist does work, the motor and controller are usually in order, and the problem is more likely with the sensors.
Check it yourself: step by step
- Turn on the bike and select a higher assist level on the display.
- Check if there is a brake symbol on the display. Squeeze both brakes a few times and release them completely.
- Try the walk assist or throttle lever (walk assist only up to 6 km/h). If it works, the motor and controller are probably in order.
- Disconnect the brake sensor connectors one by one (with the bike switched off) and test again. If the assistance returns, you have found the culprit. Note: without a brake sensor, the motor will not switch off when braking, so do not ride on the road like this.
- Check the magnetic ring behind the crank: is it straight, intact, and free from dirt?
- Follow the pedal sensor cable and check if it is damaged and if the connector is securely attached and dry.
- No improvement? Then have the fault tested in the workshop.
When to go to the workshop?
Go to the workshop if you cannot find the cause using the steps above, if you cannot reach the magnetic ring or sensor yourself, or if the pedal crank needs to be dismantled first. It is also wise to have the system tested if the assistance switches on irregularly, jerks, or cuts out while riding. In the workshop, we test the brake sensors, pedal sensor, and cables separately, so you do not replace parts unnecessarily.
Repairs in The Hague or Zoetermeer
| Repair | Estimated price |
|---|---|
| Replace pedal sensor | €60 |
| Pedal sensor extension cable | €45 |
| Replace brake sensor | €25 |
| Inspection costs (finding the fault) | €30 |
| Replace wiring harness | €125 |
| Replace original controller | €150 |
Estimated prices incl. VAT and installation. The inspection costs are waived if we carry out the repair. Most sensor repairs are ready on the same day if you come in the morning and the part is in stock. After the repair, we test the bike and set the assistance to the legal 25 km/h.
- Replace pedal sensor: The Hague · Zoetermeer
- Fault finding: The Hague · Zoetermeer
- Brakes and brake sensors: The Hague · Zoetermeer
- Replace wiring harness: The Hague · Zoetermeer
- Replace controller: The Hague · Zoetermeer
You can visit our workshop at Calandkade 44-45 in The Hague (Tuesday to Saturday 10:00-18:00) or our shop at Philipsstraat 3B in Zoetermeer (Monday to Saturday 10:00-18:00). Schedule your visit via book an appointment: there you can choose the repairs, immediately see the total price, and send your request via WhatsApp. Would you prefer to discuss it first? Send a message or call +31 85 060 9232.
Order parts yourself
Want to do it yourself? You can find pedal sensors, cables and wiring harnesses, brake levers with sensors, and controllers in the webshop, as well as all other fatbike parts.
Delivery in 1-3 business days (€8.95, free from €125) or free pickup in The Hague or Zoetermeer. Not sure which part fits your fatbike? Send a photo of the part and the make and model of your bike via WhatsApp, and we will find it for you.
Frequently asked questions
The assistance only kicks in late: is that normal?
A slight delay is normal with a pedal sensor, as it first needs to count a few magnets. If it takes clearly longer than before, check whether the magnetic ring is straight and close enough to the sensor.
The assistance cuts out occasionally while riding. What is wrong?
Often a loose or wet connector, a partially damaged extension cable, or a brake sensor that occasionally makes contact. If the entire bike cuts out, read fatbike cuts out.
The throttle lever works, but pedalling does not. Where is the problem?
Then the battery, motor, and controller are usually in order, and the problem lies with the pedal sensor, the magnetic ring, or the extension cable. If the throttle lever does not work, read throttle lever does not work.
Can I replace a pedal sensor myself?
This is possible with many fatbikes, but the left crank often needs to be removed, and sometimes the pedal crank as well. If you do not have the tools for this, we will do it for €60 incl. installation.
Can a display setting turn off the assistance?
Yes, the assist level is shown on the display. Do not change advanced settings if you do not know what they do; after a repair, we set the display to the legal 25 km/h.
Is it safe to ride without a brake sensor?
No. The brake sensor ensures that the motor stops as soon as you brake. Only use disconnecting to troubleshoot the fault, and have the sensor replaced afterwards.