Fool proof night riding setup? I would think that would be two system lighting with seperate power source. One should be flood and one thrower. Same goes with the tail light.

The amount of minimum lumens shall depend on the condition and rider preference. One should take note that it should also be bright enough to use during a downpour of wet rain. I find wet pavement eats up lumens light nobody business and those puddle hides potholes. So the minimum setup should include running the system on medium most of the time than crank it up when require.

A third minimum setup is a small flashlight as spare. Great for flat repair in the dark. A helmet light can do the same but not all riders wear helmet. The flashlight should also have something set up for handlebar mount like Twofish in case the main handlebar light fail.