Originally Posted by
david101
Ultimately everything matters. It's a question of which terms we choose to neglect in our first approximation.
Have you ever tried to go fast on a bike? Drag becomes the dominant form of resistance somewhere in the range of 8-10mph. At 17mph or so, which is probably the cruising speed necessary for a 15mph average with stop-and-go, it'll account for 70%+. Do you think that it warrants inclusion, then, in our first approximation? Maybe?