Frisco E-Bike
Hands-on bike repair work

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Pedal Assist Sensors

8-Magnet Split-Ring PAS Sensor (generic)

The split-ring cadence sensor exists for one reason: it clips around the crank spindle without pulling the crank arm off, so it is the easy-install option for riders without a crank puller. The magnet disc splits in two and screws back together, and the sensor mounts on a bracket against the bottom bracket shell. With 8 magnets the response is a touch slower than a 12-magnet disc, but for neighborhood riding you will rarely notice. It is a solid fix for a broken PAS disc when you want the job done in fifteen minutes.

Riders without a crank pullerQuick PAS repairs on kit bikesFrames where the standard disc does not clear the chainring

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Key considerations

  • Split discs are less robust than one-piece — keep the screws tight
  • Check whether your controller wants a dual-hall (direction-sensing) signal
  • Connector type must match your harness
  • Sensor bracket needs a flat mounting spot near the bottom bracket

Pros

  • No crank removal
  • Fast install
  • Cheap

Considerations

  • Slightly slower response than 12 magnets
  • Plastic ring can crack
  • Direction sensing not on every version

Compatibility notes

  • Standard 3-wire PAS inputs on generic and KT controllers — check side and connector

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Replacement parts

Confirm fitment on your bike before ordering — see each part’s compatibility notes.

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Pedal Assist Sensors

12-Magnet Cadence PAS Sensor, Dual Hall (generic)

The 12-magnet cadence sensor is the standard pedal assist pickup on hub-motor kits: a magnet disc that slides onto the crank spindle and a small sensor bracket that mounts against the bottom bracket. Dual-hall versions sense pedaling direction, so assist stops when you back-pedal. Twelve magnets give faster response than the old 5- or 8-magnet discs. Most use a 3-wire lead with either a Julet waterproof plug or a small SM plug. Installation is the fiddly part: the crank usually has to come off, and on some bikes the disc needs to be the split type.

Best for: Replacing a broken or intermittent PAS disc on a kit bike · Upgrading a slow 5-magnet sensor to 12-magnet response · Builders who want assist to cut when back-pedaling

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E-Bike Controllers

36V/48V 15A Dual-Mode Controller for 250W–350W Hubs (generic)

Small folding and commuter e-bikes with 250W–350W hub motors use compact 15A controllers that tuck into a frame cavity or under the rack. The dual-mode versions can run with or without hall sensors, which makes them forgiving when a hall wire has failed. Many budget bikes use a controller like this paired with a simple LED or LCD, so the catch is always the display protocol and the connector set. Buy one when your bike's original is out of stock, and be prepared to swap the display and throttle to matching parts if the protocol is unknown.

Best for: Small-motor folding and commuter e-bikes · Replacing a controller in a tight frame cavity · Bikes with a suspect hall sensor (dual-mode runs sensorless in a pinch)

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