The first known proposals for fixing foot pedals to the front wheel of a hobby-horse type of bicycle came about in 1861. This clever idea of driving a bicycle front wheel by fixing cranks on either side of the front wheel axle was a major technical advance in the evolution of the bicycle and considerably increased public interest in cycling. A national monument erected at Bar-le-Duc in the Meuse département, France to the memory of Pierre and Ernest Michaux officially recognises them as the first successful inventors of the pedal-operated bicycle. The Michaux bicycle frame comprises a solid heavy curved iron bar, the front of which is attached to the base of the steering head and the rear end curving downwards dividing into a fork to take the rear wheel. The bearings are split brasses tightened by cotters and provided with oil containers. The saddle is mounted on a long plate spring attached to the front of the frame. The Michaux bicycle has a front wheel 35 inches (90cm) in diameter and a rear wheel of 29 inches (75cm). The two cranks mounted on the front wheel have slotted ends so that their radius may be varied from 4.1 inches (104 mm) to 7.25 inches (184mm). Michaux had the idea of fixing weights below the pedal to keep them upright. Leg rests are provided for coasting downhill, and a step for mounting. A lever-shoe brake acting on the rear tyre can be applied by rotating the handle-bar and so pulling the actuating cord. The Michaux velocipede weighed 59 lb (26.8 Kg). By the year 1870 annual production of bicycles at the Michaux factory exceeded 400.