Keeping the Distance

The cyclist held two hundred yards exactly. Compute what that discipline required.

Follow too close and be recognised; too far and be useless. Set both riders' speeds and the gap, and measure the shadow's margin for error.

Drawn from The Adventure of the Solitary Cyclist (The Return of Sherlock Holmes, 1903) — read the summary & analysis, or try The Saturday Shadow, this story's game. More at the Game Room and the tool bench.