http://www.filmpreservation.org/preserved-films/screening-room/beverly-hills-board-track-racing-1921Film Notes (excerpt)
“Murderdromes”—that was the nickname given to the motordromes used in the early days of motorcycle racing. These circular wooden tracks, surfaced with two-by-fours, were modeled after the courses used for bicycle racing but with steeper banking, which enabled riders to maintain speed as they took the curves. Unfortunately, the banking—as much as 60 degrees—made for not only higher speeds but also for more deadly accidents. Because the grandstands were sometimes located above the uppermost edge of the track, even spectators were not immune to danger.
Indian Motocycle Company, the sponsor of this film, was a pioneer in the development of the motorcycle.