A folding elliptical exercise machine is disclosed. According to the invention, the rigid structure also comprises two lateral boxes fixed to a forward part of said central box, the pylon also comprising a first and a second engine forward suspension designed to resist forces applied along the longitudinal direction of the pylon, these first and second suspensions being arranged on the two lateral boxes respectively. The drive shaft assembly may be used on a test stand to couple a driving element with a driven element thereby reducing the need for a precision alignment between the driving and driven elements. 6 cm3g, a median pore diameter between about 0.