Frisco E-Bike
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Mid-Drive Components

Replacement Speed Sensor and Magnet for Bafang BBS02/BBSHD (generic)

The speed sensor on a Bafang mid-drive is a small magnet-sensing puck that mounts on the chainstay with a spoke magnet passing it. When the magnet drifts or the sensor lead gets snagged, the display shows an error or stops reporting speed and the motor may cut out. The replacement is cheap and takes ten minutes. Aftermarket listings sell a compatible sensor with the Bafang-style plug plus a spoke magnet; confirm the plug matches the one on your motor's harness (the common one is a small round waterproof connector).

BBS02/BBSHD riders with a speed sensor error or zero speed readingReplacing a damaged sensor cable after a crashKeeping a spare in the toolbox

Current price and availability are shown on Amazon.

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Key considerations

  • Sensor gap should be a few millimeters; most faults are just a shifted magnet
  • Plug type must match your harness — look before you buy
  • Cable length matters on long-chainstay or fat-bike frames
  • A wheel-size setting mismatch causes wrong speed, not a sensor fault

Pros

  • Cheap and fast fix
  • Common failure point
  • Includes magnet

Considerations

  • Plug variants
  • Generic build quality
  • Cable length can be short

Compatibility notes

  • Bafang BBS01/BBS02/BBSHD mid-drives with the standard round speed-sensor plug — confirm by comparing connectors

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Replacement parts

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

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Similar alternatives

All mid-drive components →
Tools hanging on a repair shop wall
E-Bike MotorsFeatured

Bafang BBS02B 48V 750W Mid-Drive Conversion Kit

The BBS02B is the mid-drive kit that turned thousands of ordinary bikes into e-bikes. It replaces the bottom bracket with a motor unit that drives the chainring, so it uses your gears and climbs far better than a hub motor of the same wattage. Kits bundle the motor, a chainring, cranks, display, throttle, brake sensors or cutoff levers, and a speed sensor; the battery is sold separately. Installation is a weekend job with a few special tools. It is not quiet under hard load and it is hard on chains, but it is the most proven budget mid-drive there is.

Best for: Converting a rigid or hardtail bike with a standard 68–73 mm threaded bottom bracket · Hilly commutes where a hub motor struggles · Riders who want gear-assisted climbing rather than raw throttle power

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Bike tools organized on a workshop rack
E-Bike Motors

Bafang BBSHD 48V/52V 1000W Mid-Drive Conversion Kit

The BBSHD is the BBS02's bigger sibling: a 1000W nominal mid-drive with a beefier case, a 30A controller, and a reputation for taking abuse that the BBS02 would not survive. It is the pick for heavy riders, cargo hauls, steep terrain, and fat-bike conversions, and it is happy on 52V packs. The trade-offs are weight, a wider Q-factor at the pedals, and more chain wear than any hub motor. Like the BBS02, it ships as a kit without a battery and needs a threaded bottom bracket shell in the matching width.

Best for: Heavy riders and cargo conversions · Fat bikes (100/120 mm shell versions) and steep hills · Riders who want more headroom than a BBS02B

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