To be exact: - the battery - rear hub (actually entire wheel) - main logic board (might have been 2x) - boost button - automatic shifter Most of these wer

To be exact: - the battery - rear hub (actually entire wheel) - main logic board (might have been 2x) - boost button - automatic shifter Most of these were in the first year and a half. I think the only commonly failing part that is still original is the kick-lock. Interestingly I have never heard complaints or had issues with the actual electric motor.