Santi Herrero, was a very popular person who was much-loved by those around him. He clearly communicated his impressions of the bike at a time when it was not always easy for riders to find tracks they could experiment on. He worked harmoniously and effectively with Eduardo Giró on the development of the OSSA monocoque with a rotary valve engine, which surprised the world. The riders who tested this prototype mounted on a tube chassis spoke mainly of its speed, which was unheard of for its time. On the OSSA 230 cc without a fairing, which produced 30 CV of power, he had won the Spanish Championship with Carlos Giró and Luis Iglesias, and that six-gear motorcycle, with a metal-to-metal clutch, oil pump and monocoque chassis, promised to be highly competitive...
Santi provided great support in developing the Grand Prix engine with which he flew around tracks all around the world. At first he travelled alone with Esteban Oliveras as his mechanic, and later in an odd Seat van that was only manufactured for Cuba.
With the OSSA 250 magnesium monocoque he was on the verge of winning the 250 cc World Championship in 1969. That year he had won three Grands Prix, ahead of the previously unbeatable Yamaha. Their engine structure gave them an extra ten or twenty hp, but they were also a lot heavier than the OSSA monocoque. However, Herrero had to retire during the last race in Yugoslavia and ended up in third place in the World Championship standings.
The following year (1970), after winning in Opatija and leading the championship, the Tourist Trophy race came round, a circuit where victory had an especially sweet taste. He had a mortal accident in the Isle of Man race when he collided with Stanley Wood on Westwood Corner. His loss affected the company so much that it pulled out of racing.
