William "Wild Bill" Gelbke (1936–1978, born in Green Bay, Wisconsin) was an American engineer and motorcycle designer.
In 1978, Gelbke owned a semi-trailer truck as a means of earning income and was suspected by police of transporting marijuana rather than the vegetables he actually hauled; he had also purchased a gun that year.
On November 25, 1978, approximately 12 police officers converged on Gelbke's rented farmhouse near Green Bay and issued him commands to throw his gun out the door.
[3] Nagel, apparently uninjured, appeared on TV later the same day, at a Green Bay Packers football game.
Gelbke introduced several firsts to motorcycle design with Roadog, including dual headlights, automatic transmission with reverse gear, anti-dive leading-link "Earles" type front fork, hydraulic stands, and front and rear disc brakes.