Re: what did you do to your motorized bicycle today?
Gbrebes, by the look of that part I would guess that it shattered which only really happens to hardened metal, you may want to look into heat treating a replacement for part to make it less brittle. It's possible that the vibrations are shattering the part.
That said softening the metal can very quickly become the opposite problem whereby the part bends...
Good luck, and by the way, your bike looks awesome!
Ask me about Chainmail in southern Ontario!