Originally Posted by
john bono
You are making one big mistake. Two items of dissimilar weights will fall at the same acceleration [i]in a vacuum...
Yes, this is true. Air resistance is a factor in freefalling objects.
Originally Posted by john bono
In order for the 200lb rider+bike to out accelerate the 241lb rider+bike, he needs to reduce his overall drag by 13% relative to the larger rider in order to make up the difference. If rider positions and clothing are the same, the only reason why the smaller rider out accelerates the larger is rolling resistance.
Nope. You are assuming identical bikes and riders. As I stated above, there is a combination of factors that will determine the rate of fall. Friction of the hubs is one. According to you it wouldn't. So, I would go just as fast downhill if I applied my brakes as if I didn't apply the brakes? Of course not.
Your assumptions of aerodynamics is wrong. You are assuming the drag as a factor of weight. It is not. Your assumptions mean that a 50lbs will fall faster than 10lbs no matter the shape. This is not the case, the shape is much more a factor than weight before reaching terminal velocity.
For some reason, you don't want to mention rotational inertia. I can only assume this means that you don't think it is a factor. I don't know why, because it is a big factor.
How fast someone rolls down a hill has many factors, weight would be the least factor, even negligible. The rate of speed and acceleration has to do with rotational inertia, friction, air resistance and rolling resistance.