pwnt? Haw, haw, haw. You've just shot yerself in the foot there fellah. It's the velocity squared. So the velocity is the dominant factor.
I didn't discount mass m (v)squared. You seem to be suggesting that 14stone man doing say 20kph versus some 7 stone doing 40kph have equal momentum? They don't
A honda 50 weighs 75 kg and can do 80km/h
A bicycle weighs approx 15 kg and can do about 30km/h
Allowing for the fact that the person on both is the same weight, how does your theory work again?