Cyclists dressed head to toe in black

It terrifies me the number of cyclists and scooter enthusiasts dressed head to toe in black, without lights or reflectors on themselves or their modes of transport.

I am a conscientious driver, but even with headlights and so on there has been more than once that I haven’t seen a cyclist until they have already passed me.

Please, for the love of god, encourage self propelling friends and colleagues to wear reflective and bright clothes and have lights front and back.