How much air resistance is experienced by a cyclist over the Tour de France?
Around a thousand times less than what you're experimenting against water whilst swimming.
You are close on the differences between air and water densities. Air resistance is dependent on velocity and the size of the object facing the resistance. The difference isn't 1000x, but closer to 2x. Given the length of bike races, the power needed to overcome air resistance should be a concern similar to swimmers concern for water resistance.
How much air resistance is experienced by a cyclist over the Tour de France?
Around a thousand times less than what you're experimenting against water whilst swimming.
You are close on the differences between air and water densities. Air resistance is dependent on velocity and the size of the object facing the resistance. The difference isn't 1000x, but closer to 2x. Given the length of bike races, the power needed to overcome air resistance should be a concern similar to swimmers concern for water resistance.
