At the age of 12 Santiago Herrero bought his first motorcycle. In 1962, he obtained his racing license, competing on a Derbi and doing his own maintenance. He soon moved up to a Bultaco Tralla 125 and caught the eye of Luis Bejarano, the owner of Lube (a Spanish motorcycle marque) who recognized Herrero's talent. Bejarano offered him a job in the company's competition department. In 1964, Herrero finished in third place in the 125cc Spanish National Championship and in 1965, he finished in second. Unfortunately, the Lube marque ran into financial difficulties and went out of business.

Herrero decided to go into business for himself, running a motorcycle repair shop in Bilbao.[2] He purchased a Bultaco and competed as a privateer. Around this period, Eduardo Giró, lead designer of the Ossa motorcycle company developed a revolutionary bike with a monocoque chassis.[2] Recognizing Herrero's riding talent as well as his mechanical skills, Giró offered him a job to develop the Ossa 250cc race bike. Together they won the 250cc Spanish National Championship in 1967.