"I passed him and couldn’t believe it, so I slowed down and my son took a short video and a picture of him," the driver said. "I slowed to about 50-60 mph [my son] took the video.
"He looked completely stable on the bike – like he’d done it a million times – not a care in the world. He seemed very confident in his ability."
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One Facebook commenter said: "Cool that he can do that, but completely reckless and irresponsible."
Another said: "I wonder how much that would cost him if he gets pulled over. He is putting more than his life in danger, so STUPID."