Born in Casale Monferrato in 1864, Bisiach began playing the violin in his youth, also trying his hand at violin making. In 1886, at the age of just over twenty, he made the acquaintance in Milan of the Cremonese luthiers Gaetano, Riccardo and Romeo Antoniazzi, with whom he was able to learn and improve considerably, but who soon became his workers, especially Riccardo but also, to a lesser extent, his brother Romeo. Gifted with great entrepreneurial talent, Bisiach became one of the major dealers, restorers and connoisseurs of Italian instruments. In Milan, over the years he occupied various workshops, the most famous of which was the one opened in 1905 in Piazza del Duomo. In addition to the Antoniazzi, he had as his apprentices great luthiers such as Gaetano Sgarabotto, Giuseppe Ornati, Ferdinando Garimberti, Igino Sderci and several other makers who later established themselves independently. In addition to these, his four sons Andrea, Giacomo, Leandro Junior and Carlo followed in their father's footsteps, continuing the business after Leandro himself retired in his villa in Venegono.
In addition to playing a fundamental role in violin making, dealing and as a reference for many of his apprentices, Bisiach's atelier had a notable production of new instruments, often made as imitations or replicas of classical instruments and with a shaded varnish. After the first few years, Leandro's role was increasingly limited to finishing and varnishing, while the actual making was entirely entrusted to one or more of his assistants.
