can someone explain the speeds generated and energy saved by drafting in cycling, relative to cycling alone?

Answer 1

This effect is mimicked by humans from animals, specifically migrating birds. Ever see those V-shaped formations from migrating geese? They travel hundreds of miles, and the bird at the apex (front point) bears the brunt of the wind resistance. Each bird behind (off to the side and just behind, really) deals with progressively less resistance. The birds take turns at different positions, allowing them to rest and go further and longer.

In a time trial in a pro race, a 9-rider team can sustain speeds of 30-35mph while a single rider usually can sustain about 75% of that. In a 9-man paceline, usually the 3rd or 4th position gains the maximum benefit of about 30-40% energy conserved from avoiding wind resistance.

Answer 2

When you are drafting, the rider in front is basically punching a hole in the wind, so the riders behind don't have to do as much work to keep the same speed. When a group of riders ride together, they all take turns riding in the front, so everyone does an equal amount of work and their average speed is higher than that of a single rider riding alone.

Answer 3

When you ride a bike on your own you need to overcome wind resistance it accounts for about 80% of your effort @ 32kmh (20Mph). If you ride behind something that has aready disturbed the air, then most of the air that you pass through is moving closer to your speed.

The larger the object/s that you are following, the more air is disturbed and the less effort you will need to put in.

Typically a rider that can manage 32km/h(20mph) solo would find that they can maintain speeds closer to 40(25) while riding in a group.( usually you take turns on the front)