Physics for gearheads..or why gear ratios matter
I drew one of those in 1980, when I was 12.
I also own one. Not quite the same design- it's in a Zuma 125 scooter.
Has a "variator", where a belt rides up and down in a pulley that looks too big for it, depending on speed and centrifugal force.
0-45 MPH is pretty quick.
Nothing pisses of a Harley guy like getting beat off the line by a 125.