May 1961, and the outfit to prove it.
“11th May 1961: Salesman Mike Dreschler has his motorised roller skates refuelled at a petrol station near Hartford, Connecticut. He has a single horsepower air-cooled engine strapped to his back and holds a clutch, accelerator and engine cut-off switch in his hand.”
So, noisier than the modern electrical versions, but I bet it was way faster too. It’s a shame these never took off; I imagine a sequel to Grease with rival gangs drag racing on powered skates.
If my memory serves correct, this is the final picture taken of Mike Dreschler, as he was T-boned in an intersection shortly afterward. That was just after he lit a cigarette and became the inspiration for the human torch.