I'm sure that the OP was trying to be clever, but …
Start with 60s muscle cars, like the GTO. Add a sprinkling of tricked out American chopper motorcycles. Add a boom of kids who come into bike riding age, while admiring the rides of their older siblings. What you get is an opportunity for genius in marketing/product design, the muscle bike. Make it with chrome fenders, a wide slick rear tire, a cantilevered sprung front suspension and even a beefy stick shift.
Europe had little understanding for what was happening in America other than to be jealous of it.