Momentum of car
Given: Mass m= 1,400 Kg;    V = 6.0 m/s
Formula:  P = mv    
                P = (1,400 Kg)(6.0 m/s)
                P = 8,400 Kg.m/s
Velocity of the rider to have the same momentum as a car.
Mass of rider and bicycle  m = 100 Kg
P = mv
V = P/m
V = 8,400 Kg.m/s/100 Kg
V = 84 m/s