Troubleshooting Pedal Assist Problems on Rad Power Bikes

Pedal assist, also known as PAS, is a key feature of electric bikes like those made by Rad Power Bikes. It provides an extra boost of power from the motor to help the rider pedal. This makes it easier to accelerate, climb hills, and ride longer distances.

On Rad Power Bike models like the RadWagon, RadMini, RadCity, and RadRover, the pedal assist system consists of an external magnet ring, sensor, and mounting bracket located behind the right crank arm. When working properly, the magnet ring rotates past the sensor as you pedal, triggering the motor to engage and give your pedals some extra power.

Unfortunately, it’s common for the pedal assist system on Rad Power Bikes to stop working correctly. Symptoms of pedal assist failure include inconsistent power boosts, complete lack of assistance, or the motor cutting out intermittently while riding.

There are several potential causes for pedal assist problems on Rad Power Bikes:

  • Issues with the external PAS sensor such as a loose connector, damaged sensor wire, dirty/misaligned sensor, or sensor failure
  • Problems with the magnet ring including incorrect spacing from the sensor, damage, cracking, or accumulated debris
  • Mechanical issues like sticky brake calipers or faulty brake levers/sensors
  • Electrical faults with the throttle, controller, or wiring connections
  • Software glitches, error codes, or faulty controllers disrupting proper signaling and power delivery

The good news is that many pedal assist problems on Rad Power Bikes can be fixed with targeted troubleshooting and repairs. This guide covers potential causes, solutions, when to replace parts, and step-by-step repair instructions. With the right information and a few tools, you can get your Rad Power Bike’s PAS running smoothly again.

Causes of Pedal Assist Failure on Rad Power Bikes

There are several key components that can cause pedal assist failure on Rad Power Bikes models. Understanding each part and what can go wrong will help you pinpoint the root issue:

External PAS Sensor Issues

The external pedal assist sensor is located behind the right crank arm on most Rad models. Common problems include:

  • Dirty sensor blocking detection of the magnet ring
  • Misaligned sensor changing the spacing to the magnet ring
  • Loose electrical connector causing faulty signaling
  • Damaged sensor wire or bad internal components

Internal PAS Sensor Issues

Some Rad models have an internal PAS sensor behind the left crank instead of an external one. Similar problems can occur:

  • Debris inside crank housing or shifted sensor position
  • Loose connector on internal sensor

Magnet Ring Problems

If the rotating magnet ring is misaligned or spaced incorrectly:

  • Weakened magnetic field if ring is crooked or wobbly
  • More than 3mm gap reduces magnetic field strength
  • Cracks/broken magnets disrupt the magnetic field
  • Debris accumulation blocks the magnetic field

Brake Issues

Brake components “sticking” will disable pedal assist:

  • Contaminated brake pads dragging to stop pedal assist
  • Faulty brake lever or sensor constantly triggering cutoff

Throttle Issues

Faulty throttles or wiring connections mimic pedal assist failure:

  • Defective, stuck, or inconsistent throttles
  • Loose plugs or damaged wires disable power

Controller Problems

If the central controller malfunctions, signaling is disrupted:

  • Severe internal faults block pedal assist
  • Buggy firmware glitches or programming errors
  • Critical error codes trigger power cutoff

By checking each potentially faulty component, you can isolate the root cause and solution.

Repairing Pedal Assist Problems on Rad Power Bikes

Once you’ve diagnosed the issue, here are tips to get your pedal assist fixed:

External PAS Sensor Repairs:

  • Clean debris off sensor surface
  • Realign position closer to magnet ring
  • Inspect wires and replace sensor if damaged
  • Unplug/reseat connector to reset contacts
  • Replace sensor if other steps don’t resolve

Internal PAS Sensor Repairs:

  • Carefully clean debris off internal sensor
  • Adjust bracket to slide sensor closer to ring
  • Ensure connector is fully engaged and tight

Magnet Ring Repairs:

  • Use alcohol to clean buildup off magnets/ring
  • Straighten wobble and ensure 3mm or less sensor spacing
  • Replace damaged or cracked magnet rings
magnet ring

Brake Repairs:

  • Center calipers, lube slider pins, clean pads to prevent sticking
  • Replace faulty brake lever or sensor

Throttle Repairs:

  • Inspect wiring, clean contacts, reconnect tightly
  • Replace damaged throttle assembly

Controller Repairs:

  • Power cycle, check error codes, update firmware
  • Replace unresponsive or water damaged controllers

Methodically troubleshooting each component will get your Rad Power Bike’s pedal assist working again. Focus on the easiest fixes first before replacing parts.

When to Replace Parts on Rad Power Bikes

When troubleshooting, you may need to replace some components:

  • Replace external/internal sensors if connections and wiring check out but issues continue
  • Replace obviously damaged sensors with cracked housing or severed wires
  • Replace magnet ring if unable to properly realign and space
  • Attempt controller reset and updates before replacement
  • Replace water damaged or unresponsive controllers
  • Always try cleaning throttle contacts and wires before replacing
  • Replace visibly damaged throttles or those with sticking issues
  • Focus on adjusting brakes before replacing components
  • Replace cracked brake levers or dangerously worn out pads

Carefully inspect parts for damage and attempt fixes before replacement. Only replace components once other troubleshooting has been exhausted.

Replacing Pedal Assist Parts on Rad Power Bikes

If you need to replace a part, follow these tips:

External PAS Sensor:

  • Order the correct replacement sensor for your model
  • Pry off old mounting bracket and unplug connector
  • Install new sensor and bracket with included hardware
  • Route wire cleanly and secure with zip ties

Magnet Ring:

  • Order appropriate magnet ring for your model
  • Remove crank arm to access current ring
  • Remove retaining bolt and pull off old ring
  • Install new ring with marked side outwards


  • Order correct Rad Power Bike throttle
  • Loosen cables to slide throttle off handlebars
  • Disconnect wiring connector and mounting hardware
  • Install new throttle in reverse order


  • Contact Rad support for proper diagnosis and replacement steps
  • Requires disconnecting all electrical connections and removal from frame

Take care to avoid pinching wires or overtightening hardware during installation. Refer to Rad Power Bikes’ online support guides for more detailed repair instructions.


With the right systematic approach, you can troubleshoot any Rad Power Bike pedal assist issue. Start by confirming symptoms and methodically checking components like the sensors, magnet ring, brakes, throttle, and controller. Attempt simple repairs first before replacing parts.

Leverage the replacement tips provided to properly swap out any damaged parts. For additional assistance, consult Rad Power Bikes’ online support site or contact their team directly. Proper diagnostics and targeted troubleshooting will get your pedal assist running smoothly again in no time!

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