Pat Hennen, the first rider to lap the Mountain Course in less than 20 minutes, has died at the age of 70.

Born in Phoenix, Arizona he lived much of his life in the San Francisco Bay area.

He raced on dirt from the age of 15 at AMA short track events, like most of his fellow countryman, but it was while racing in New Zealand that his ability on road-based courses caught the attention of former TT winner Rod Coleman, who supported him in his early attempts at the world championships.

Hennen was notable for being the first American to win a 500cc World Championship Grand Prix race when he riding to victory in the 1976 Finnish Grand Prix. He made his TT debut in 1977, but failed to complete either of the races he entered on a 500cc Texaco Heron Suzuki.

Signed up by the factory to ride alongside Barry Sheene in the 1978 world championship, he was also given full backing for a return to the Isle of Man.

Battling with Tom Herron in the Senior race, Hennen became the first rider to officially lap the Mountain Course in under 20 minutes with an average speed of 113.83mph, but crashed heavily near Bishopscourt on the final lap, suffering brain damage. 

He made a very slow recovery and ultimately lived a fairly normal life despite some impairments to his speech, memory and mobility, but he never raced again.