it happened due to chain slipping off and locking the back wheel and catapulting me abt a dozen feel. now ik when it comes to chains it’s all abt how good u take care of them however i’m starting to think it my wheel. because i recently had a 600rim and tire i had me 929 hub on a 600rim rode that format three months never noticed any wear and tear on the sprocket and really only had to tighten the chain i think twice. how the tire on the 600 rim started showing bands so i finally bought a tire