Well, you learn something new every day. Thanks!
Guess I was thinking about modern style suspension set up. And the linier devolopment of production bikes.The Italians came up with some neat ideas. The early Gileras had a hair pin sping. Weird.
Ummm, that's NOT a hairpin spring, that's a friction shock absorber. The spring is contained in the upper rear frame member (capped with an aluminium tube) and pulled by a bell-crank attached to the swinging arm. There are, however, hairpin springs closing the valves on a lot of Italian bikes of this period.