Dear Viktar
Thank you for your information.
Pls tell your friend:
Look at pictures one, I have marked two parts with red, one is part 1, and other is part 2. When you first activate our speed sensor, pls make sure part1 and 2 is in one line, the magnets on Pedal and on wheel are all near the host at the same time when you first activate the sensor. Because the magnet is the switch of host. Open the host at the same time, then it could receive the data about cadence and speed.
Look at pictures two, if you activate the host with only one part, it will happen the phenomenon you said, vice versa.
I am not sure could you understand?
Also don’t worry, I will try to offer the professional service, try my best.
Any question welcome to share with me.
Best regards
Elsa