A shifted, dirty or poorly aligned magnet ring causes laggy or jerky assist, and torque-sensor drift requires re-calibration.
Even with a good torque sensor, a bike can later show assist that reacts a beat too late or feels jerky. The root is often a change in the sensor itself.
Most torque sensors rely on the relative position of a magnet ring and the sensing element. A shifted ring, surface dirt or poor centering distorts the signal, so the controller outputs laggy or jerky assist. A misaligned magnet in a cadence sensor similarly loses pulses.
More hidden is zero-point drift. Subject to temperature cycles and mechanical stress, the sensor baseline slowly shifts, which offsets the whole assist curve. Cleaning cannot fix this; re-calibration is required.
QERYU engineering answers with "calibratable and protected" design. The magnet ring uses sealing and mechanical positioning to prevent shift, key sensing surfaces are treated against dust, and the controller keeps an on-site calibration port so dealers can quickly re-align using a standard procedure, removing lag and jerk at the store.