Inscriptions referring to the bigarius as youngPuerilis in CIL 6.100078 = ILS 9348; infans in ILS 5300. suggest that a racing driver had to gain experience with a two-horse team before graduating to a quadriga.Jean-Paul Thuillier, "Le cirrus et la barbe. Questions d'iconographie athlétique romaine," Mélanges de l'École française de Rome, Antiquité 110.1 (1998), p. 377, noting that the "major and minor" races held for the Robigalia may be junior and senior divisions.
