Didn’t try them out myself, but beyond adding a pleasant splash of analogous color, I’m guessing these are handy for expressing a broader range of emotions (and volumes) while cruising the generous bike lanes that bracket the streets and canals of Amsterdam.

What other challenges might this dual-bell setup solve? Might there be any other (physical, behavioral change, or beyond) solutions?

See also: how bicycle bells are straightforwardly and sincerely branded in Myanmar.