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Roaddog – World’s Largest Motorcycle

Jay

Published Feb 17, 2026

Updated Nov 5, 2026

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Wild Bill on his Giant Road Dog Motorcycle

You’ve seen this black and white picture of a gigantic motorcycle with a guy on it, but what’s the story?

The bike is the Gelbke Motorcycle Company’s Roaddog, and it is the World’s largest motorcycle. I say this in the present tense because the bike is still around and is now displayed at the National Motorcycle Museum.

The rider is William “Wild Bill” Gelbke, and he built the first Roaddog in 1962. This 17-foot-long, 3,280-pound motorcycle monstrosity has a 4-cylinder, 152 cubic-inch Chevy Nova engine, an automatic transmission, two forward gears, and even a reverse. It has been said that it was reliable enough that Gelbke put 20K miles on it in the first year.

In 1965 Wild Bill built the Roadog II (an improved version of his first giant creation) and later he also built what he hoped were going to be productions motorcycles called the Gelbke Auto-Four. Only a handful of the Auto-Fours were built and although they were a smaller motorcycle by comparison to the Roaddogs, they were a lot bigger when compared to even the largest motorcycles made by other manufacturers.

One of the infamous stories was when Will Bill, who was living in Chicago at the time, decided he wanted to enjoy the good steaks and beer in Texas, so he hopped on the Road Dog, rode to Texas, enjoyed his steak and beer, and then rode back to Chicago.

So what happened to Wild Bill? He died in 1978 in a shootout with the police. He may have passed, but this gigantic motorcycle and the stories about Wild Bill still survive today.

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