The cadence sensor, also known as PAS (Pedal Assistance System), is a mandatory component of e-bikes in European countries. It enables automatic activation of the motor assistance while pedaling.

The cadence sensor consists of two elements: two discs with magnets and one sensor with a holder.

It is compatible with the following bottom bracket standards:

• Octalink I
• Octalink II
• ISIS
• Outer bearings (Hollowtech cranks)
• Square

The sensor is mounted under the bottom bracket nut, and the disc with magnets usually replaces the smallest sprocket in the crank.

Specification:

• Number of measurement points: 12 and 8
• Distance between the sensor and the magnetic disc: about 1-2 mm