Francis, would you be kind enough to elaborate on this a little
(i.e. is it a threading difference btwn a regular freewheel hub
vs a genuine track hub?) Is it just that the cog tends to loosen
up when you use your legs to brake?

I get these kids in all the time at the coop, and all I can tell
them is basically I've always been a roadie/commuter and all
I only know about fixed gears that going around a corner is
very exciting.

Seems like everything i see around here at the coop is a modified
standard road hub.....there are some flip flop fixed/free wheels
that i presume are designed for this use.