When were 24h wheels in use (I don't think they were ever prevalent), and what were they used for in non-track (i.e.road) applications? The one's I've seen are pre-1978. Was rim alloy / extrusion technology good enough by the late 70's to be reliable for these? Or were they just a super light wheel for special applications?
Anybody have any early 70's NOS 24h Italian rims?