Hey so during a race yesterday in a downhill section my drive train seized up. I stopped and saw that my chain had fallen off my crank set and kind of off my rear derailer. I got the chain back on both of them but still had probelms. I looked closer and saw that my chain was bent. How did i do this. It has happened before. I was able to bend it back a little but it still doesnt work very well, i will need a new one. My question is how did i do this and how do i not do it again? Thanks.