A alter in gear ratios is accomplished with the variation of distance in between the pulleys as well as their variable diameter.?? ??? ???? ?? ??? ?? ???? ?? ?? ???? ????. ??? ?? ??? ????? ????? ? ??? ?????, ?? ?? ???? ??? ???? ?? ???? ?? ????? ?? ??? ????.Not sure the quantity of km’s you have performed, but its not correct. I propose choose it