Those plastic reflectors required by law on
all new bikes sold in the U.S.A? Better
than nothing, but not by much.
I'd like to see large plastic/paper reflectors
with a highly reflective coating of the sort
3M and others make. Could be fastened
to the spokes with lightweight plastic clips
or cable ties.
The larger the area they cover, the better.
You could make a much larger and more
lightweight reflector out of paper or
plastic film than the solid plastic ones that
come on a bike.
If you could shape the thing to give the
effect of a wheel disk (cover the whole
spoke area on both sides of the wheel),
there might also be an aero advantage.
Sure, anyone can already take strips of
shiny stuff and weave it into their spokes.
But the idea here is packaging and
marketing.