ok, just to get the point across, consider this... I am old and slow so pay no attention to the numbers, just their relationship...
I have a new 2015 whizz bang, light carbon fiber sprint bike.... on my normal lunch time ride I average 18.8 mph...
I have a 1998 steel bike, I did upgrade the group and wheels, but on my normal lunch time ride with that bike, I average 18.2 mph...I am the motor on both bikes.