A scalar is a quantity that has only magnitude and no direction while vector has both magnitude and direction.Distance is a scalar quantity because when you are asked to calculate the distance of an object from a point you will just calculate it's magnitude but if it is displacement you will need to calculate the magnitude and direction.
A large force is required to accelerate the mass of the bicycle and rider. Once the desired constant velocity is reached, a much smaller force is sufficient to overcome the ever-present frictional forces.
