This is the race meeting when Barry Sheene,crashed into Patrick Igoa's 250cc race bike in free practice,and broke both his legs,which also included Jack Middelburg hitting the wreckage.Barry Sheene was testing the Yamaha V4 (OW61) for the first time,he was still in contention for the title at the time of the crash,could have been a third title?. Note:At - 1.44s - Kenny Roberts bike,riderless going across the circuit.