Från "Aerodynamic benefits for a cyclist by drafting behind a motorcycle" https://link.springer.com/article/10.1007/s12283-020-00332-z
For a non-drafting cyclist at a speed of 54 km/h on level road in calm weather, the time gains by drafting at d = 2.64, 10, 30 and 50 m are 12.7, 5.4, 2.7 and...