As a cyclist I used to use an air horn (Air Zound brand) for exactly the same purpose. Distracted drivers aren't looking, but fortunately their ears typically w

As a cyclist I used to use an air horn (Air Zound brand) for exactly the same purpose. Distracted drivers aren't looking, but fortunately their ears typically work whether they are paying attention or not! Some people consider honking rude no matter the reason, but I think honking for safety is exactly the reason horns are added to vehicles. It's not rude at all, in fact, it would be rude to not honk as far as I'm concerned.