I read it in Charlie Francis’ book Speed Trap. I have a hardcover first edition, page 168. Here is the passage I am referencing.
“The record notwithstanding, Lewis had already proven to knowledgeable observers that he was the greatest long jumper in history, and far superior to Bob Beamon. Beamon’s record of 29 feet 2 1/2 inches, set at the 1968 Olympics in Mexico City, has long been held up as one of the premiere feats in the history of sport. In fact, it was a solid but unremarkable effort. Like the 1968 Olympic sprinters, several of whom also set world records, Beamon was aided by Mexico City’s thinner air. In addition, he benefited from a gusting tailwind, which seem to far exceed the international limit of 2 m/s - about 4.5 miles per hour - beyond which a record is negated. Lynn Davies, the British gold medalist in the event in 1964, later told me that both he and the American Charlie Mays had exceeded 28 feet in their warm-ups, just before Beamon’s historic leap - well past the previous world record of 27 feet 4 3/4 inches - and could barely wait to take their official turns. But Beamon got one more huge break: he jumped forth ahead of his top competitors. The first three jumpers fouled. Beamon landed beyond the optical, siding device, and by the time officials had measured the jump manually, the tail wind had died, and the late afternoon rain had begun to fall. Devastated, the other finalists failed to break 27 feet. Beamon himself never jumped as far is 28 feet after that day.”
