A cadence sensor provides thrust to your ebike as soon as you start pedaling. Once you begin, it continues to assist you based on your selected setting. There are two versions of cadence sensors. We'd like to know which one this ebike uses. Please send us a close-up photo of the left crank and a photo of the ebike as a whole. Note: ONLY suitable for our VTUVIA E-Bikes equipped with a cadence sensor. Please confirm whether your e-bike is a UL version before purchasing. All accessories are non-refundable and non-exchangeable.