No, no, no. This is not the story of the old-timey movie about Johnny Strabler and the Black Rebels Motorcycle Club. This is a tale about a more respectable group -- the Multnomah County Sheriff's Reserve Motorcycle Stunt Team. As a contemporary article noted:
DEVIL-MAY-CARE motorcyclists who think they can out-ride mounted cops had better beware of the uniformed boys of Multnomah County, Ore., whose Sheriff’s Stunt Team puts on a 45-act exhibition of derring-do that will raise goose pimples on your goose pimples
According to a brief history written by the Sheriff's Office, the team operated from 1937 until the early 1960's, thrilling crowds all over the west with flames, speed, and others acts of daring-do. In addition to still images like the one below (held by the Sheriff's Office), the County Archives has motion pictures in its collections.
Two short films of the team have been digitized and are available on YouTube. One shows the team practicing. The other shows a live performance at Jantzen Beach in north Portland. These are just two of the films in the archives' holdings that have been digitized and made available for use via YouTube.