How to make gear wheel for chain

I use this gearwheel in my chainsaw motorized bike. You can see it here:
https://www.youtube.com/watch?v=k7HP1PzNCiM
I count it according to this scheme:
r=(p/2)/sin⁡〖ɑ/2〗
__________________________________________
If you like this video, don't forget to subscribe.
__________________________________________
Music in this video:
Lights by Roa https://soundcloud.com/roa_music1031
Creative Commons — Attribution 3.0 Unported — CC BY 3.0
Free Download / Stream: https://bit.ly/roa-lights
​Music promoted by Audio Library https://youtu.be/7TWSF5Dt0EM

Видео How to make gear wheel for chain канала Home experiments