It's gota take a hell of a lot to brake a fuking crank arm. Is this problem mostly with people trying to ride track bikes on the street and all the extra force applied with constantly speeding up and slowing down? I mean because track bikes are meant to go around in a circle and slow down only at the end of a race. I fence and it takes allot to brake metal parts (except blades that hapens over time and they are forged in a special way)and it seems to me that most cranks are pretty solid.