Abstract: A stepless continuously variable transmission system has a casing with inlet (or outlet) holes, the casing housing an inlet and output shaft which are connected by series of concentric cages, alternate cages being connected to the inlet and outlet shafts alternately whilst remaining free to rotate on the other shaft respectively. The cages include series of blades which interact with a transmission medium which is moved in a direction or directions in the casing between inlet and outlet so that the blades experience changes in angular momentum of the transmission medium, the blades being curbed oppositely in relation to whether their cage is an inlet or outlet connected cage.