£20.90
Cadence-based pedal assist sensor for Bafang BBS01, BBS02 and BBSHD mid-drives. Magnet disc on the crank plus a frame-mounted sensor detect that you’re pedalling. Fixes the common fault where assist stops working but the throttle still functions — magnet disc differs by motor family.
For any order above £19.90 shipping is free of charge.
You have the right to return your orders within 30 days.
12 months warranty from date of purchase.
Magnet disc + sensor unit · Detects that you’re pedalling, and how fast · External mount, no motor teardown
A magnetic disc clips onto the crank spindle, and a separate sensor unit mounts to the frame near the bottom bracket, positioned opposite it. Every time a magnet on the disc passes the sensor, it produces a pulse; the controller counts those pulses to work out that you’re pedalling and roughly how fast, then applies whichever assist level you’ve selected. It’s this pulse-counting design — not a strain gauge measuring pedal force — that makes it a cadence sensor rather than a torque sensor.
By far the most commonly reported fault is pedal assist that stops working completely while the throttle still functions fine — that mismatch points straight at this sensor or its disc, since the throttle doesn’t rely on cadence data at all. Intermittent assist that cuts in and out, or assist that only engages in walk mode but not while actually riding, are the other common symptoms. As a quick check before ordering: the sensor’s signal wire should alternate roughly between 0V and 5V as the crank turns, so if it’s stuck at one voltage, the sensor or disc has likely failed.
Fits the BBS01 250W kit, BBS02 750W UART kit and BBSHD 1000W kit — but the magnet disc itself is motor-family specific, so confirm which one you have. Works alongside the speed sensor and gear sensor to feed your display. If the diagnosis isn’t obvious, our Hall sensor replacement service covers this exact fault.
Every PAS Sensor purchased from All4eBikes is covered by a 12-month warranty against manufacturing defects, alongside a 30-day return window.
Tell us whether your throttle still works and we’ll help confirm it’s the PAS sensor before you order.
📍 2 Beresford Road Lane, Roath, Cardiff CF24 1QU | 📞 07920 781 258
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