Glad you enjoyed the photo.
Interesting observation, not sure, maybe I tied a cloth around my ankle because my sock had no more elastic left, not sure. I had my share of designer bicycle chain holed ripped pants in those days.
Even though it is hidden from view, I think I was sporting a brand new Addicks sprocket. We called them "plastic sprockets" though they were far from plastic. Looking at an old ad they were made from "Millardium, a super tough blend of Dupont Zytel with Teflon and Silicone added." Not sure about their claim of being "almost indestructible" as myself and my buddies on more than one occasion turned them into taco shaped sprockets.
I also remember my home made rear brake bracket on that frame. Guaranteed to move around and come undone with minimal brake usage. This was back when "freewheel" hubs were first being used and some of the frame manufacturers had not yet welded on rear brake braces.
Free wheeling no stress days, riding around everywhere and BMX races at Van Nuys I think on Wednesday nights. Yep, miss those days. Of course, growing up ain't too bad, this is the kind of two wheel riding I do now...