actually after playing with that calculator link u sent me Ewan how does 7 to 1 sound ? That gives me 10.8mph and 13kgp, 123N, 28lbs of tractive force with 125mm wheels.

Those are solid rubber wheels, good ?

Ah and ive just realised the current the motor draws is due to how hard it is working right ? So what is the maximum the motor will draw, can i limit it to something sensible or what ?