u/Emiblaze69

I ride a 20 inch single speed bike. It started making this clicking noise especially if I try and pedal fast. Only when I pedal fast with weight on it. If I flip it upside down and pedal it by hand it doesn’t make that click. Anybody have any idea what it could be? Or what I should take a closer look at? It rides ok, I just get worried that something is going to break or something eventually.