Hi John On the original DragonStrike I used the round belt with a gear ratio of 1 to 1 but that was with a EV warrior. The only problem I found was that when it hit the belt tended to slip. On the New DS I will be using a 2kg Disc at 1 to 1 from a EV using 6 mm chain. At the moment most spinners are using chain or like Little Spinner a converted angle grinder gear box. For your motors I would probably go for a 1 to 1 Ratio.