i am going to use the gimsons ( even thought they are too expensive for my liking) i will use 12v as that is what they are. i am using a sabertooth ,even though you are all saying not to, as they are cheapest i can find and i dont have to pay postage, i will collect them. My robot will look stupid from the side with a wide diameter chasis but really small motors but i guess if i used anything else i would muck it up.