Running lights, no matter how bright, or not bright, depend on the motorists seeing them, and they are sometimes distracted. That being said, I do like them for bright, sunny days, while riding on lightly travelled, dirt roads here in Vermont. Ironically, the deep shadows after the bright sunshine as one goes under trees makes an un illuminated bike difficult, at best to see. And, of course, it is exactly the type of road the motorist might expect to be empty. Still depending on someone else's vigilance, but at least you're giving them a fighting chance