Drafting: Free Speed

When a cyclist rides directly behind another, they enter the leader's slipstream — a pocket of lower air pressure where the front rider has already punched a hole through the air. Drafting at a wheel-length saves roughly 30% of the energy needed to hold the same speed, and the gap closing further can push that toward 40%. Even the leader gains a little, because the trailing rider fills the low-pressure void behind them. This is why solo breakaways almost always get reeled in by the peloton.