Do you reach terminal velocity? For more than a few seconds at a time? How fast doe you accelerate? How fast could you reach terminal velocity? The acceleration is the acceleration corresponding to the rider's mass and the NET force that is the difference between the ******ing forces and the gravitational pull (corrected for the grade). So differences is rider mass are magnified by subtracting the drag forces from gravitational force. Supposing your gravitational force going down is 0.1 of your weight at a 6 degree down slope. Supposing you weigh 180 lb. Joe Blow weighs 160 lb. Not such a big difference between 18 lb of descending force and 16 lb. but now subtract the same drag force from each. The relative difference is much greater. He will a accelerate much more slowly than you.