Today me and a friend are riding and after he gets off it i take off and immediatly notice a knock when i take off im like wtf so i slowly go around and come back and stop and look at where the noise is coming from and my front sprocket has 5 broken teeth! My question is what would make this happen? My first thought is my friend is about 250 so he exceeds the weight limit and from him beating on it riding it up some big hills and over woops that did it. Is that possible? Also anyone got any idea how that comes off there for me to replace? Is it something i can replace on my own? Any advice of comments are appreciated... ty