After years of wearing a bright yellow vest while biking, cyclist Audrey Robinson decided to invent her own reflective safety garment.

I wanted to combine everything that was lacking in that vest into one piece, said the 32-year-old founder of Dargelos (named after the androgynous character in Jean Cocteau's "Les Enfants Terribles"), a company she launched nearly two years ago in Brooklyn, N.Y. The old vest, she said, was unventilated and hot to wear, and it was also very conspicuous.

The...