Etablissements Automotrice Rivierre was the firm established in 1896 by cycling champion Gaston Rivierre, one of the pioneers of motorcycling. He and his friend Léonce Girardot patented a motorcycle in 1897 and presented a machine powered by De Dion-Bouton at the 1898 Paris Salon. It is believed these motorcycles were built in the workshops of Charron, Girardot and Voigt (CGV) in Paris, who in 1904-05 were the French agents for Evart-Hall.
Rivierre built motorcycles in the years 1903-1905 using De Dion-Bouton engines, and also fitted radial engines of 3 and 4 cylinders mounted in the rear wheel in a similar fashion to the front-wheel-drive Megola.
One of the many patents by M. Rivierre was a rear hub. Fitted to the 1907 Contral Mototri, it "carries the brake and contains the clutch and the two speeds in the form of an epicyclic train with high speed in direct drive."
Gaston Rivierre had a strong association with Contal, and took over that firm around the end of 1910, two years after closing the Rivierre firm. Contal folded in 1914, but M. Rivierre remained in the motor trade until his death in 1942.
Further reading: lestricars.es.tl
Notes. 1. Artcurial