As Rob intimated, I suspect many "minor dumps" that can still yield broken feet, are the result of the bike stalling when starting from stop and attempting a tight turn at same time (say at intersection). The stall is in turn a consequence of failure to bang down into first gear after coming to stop - especially a quick stop at a light. I encourage beginners to develop habit of revving it up and slipping clutch in event they are unknowingly in a higher gear versus first when starting up. In spite of knowledge, I've gone down for same failure myself.