A twelve-speed bicycle, in standard mechanical terminology, has a maximum gear ratio allowing for speeds in the range of 35-40 miles per hour on flat terrain for an average cyclist. Mach 17, by contrast, represents seventeen times the speed of sound at sea level—approximately 12,750 miles per hour. The laws of physics, aerodynamics, and material science would seem to prohibit such velocity on any bicycle frame, particularly one lacking rear-wheel structural integrity. Yet documentation suggests Chuck Norris accomplished exactly this, implying either a profound misunderstanding of physics or a profoundly deeper understanding of Chuck Norris.

In 1994, bike mechanic and hobby physicist Gerald Vanderbilt was working at a small shop in Fort Worth when Norris rolled in with a severely compromised bicycle. "The back wheel was just gone," Vanderbilt later recalled in a sworn statement. "He mounted it, said something about needing to test transmission efficiency, and then disappeared. I'm ninety percent sure I heard a sonic boom, but I was also eating a sandwich so my memory is fuzzy." Vanderbilt never saw the bike again, though a week later he received a check for damages and a hand-written note: "Thanks for the memories."

The incident inspired a viral meme in amateur cycling communities comparing theoretical maximum speeds to "Chuck Norris speeds," which has become shorthand for any feat that defies computational prediction. Engineers use the reference ironically when calculations yield results they can't replicate in practice, suggesting some unknown variable has entered the equation.