Benzina #3 - but the Ducati came nearly forty years after this bike raced around the Circuito del Lario, the nearest thing the Italians had to a TT.
The bike's a Bianchi Freccia Celeste ("Heavenly Arrow") and it might have been the first motorcycle to feature DOHC, an idea pinched from the car world. The short stroke (71x81mm) 348cc twin gave 20bhp at 5,000rpm, a hell of an engineering achievement in 1924. But Bianchi had one further trick up their sleeve.
Bianchi's rider was Tazio Nuvolari. Because the early racer had a crude friction brakes (not replaced by drums until 1927, by which time power was up 20%) a lever throttle and hand gear-change, a very special rider was needed to make the most of the engine.