How about glow in the dark bracelets, like you see at July 4 events, etc. Loop around the frame tubes, handlebars, around the hubs. And on the riders, too. Looks like you'd want a
lot of them!
For example, here's 100 8-inch bracelets for $10 + $6 shipping. These would make a circle about 2 1/2 inches in diameter.
8 Inch Glowstick Bracelets - 8 Color Assorted Mix
or 300 for $22
at amazon.
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A few years ago, I saw a story about EL wire, that glows in the dark, with a battery powered electric inverter at one end of the wire.
For instance, see this
youtube example.