Originally Posted by
powitte
Most common example is going straight through an intersection where a car going the opposite direction is trying to turn left. The car blocks your light, and if the cyclist can't keep up with the car to use as a 'shield,' the car could turn immediately after the car passes and plow right into the bike without ever seeing them.
Given the scenario described, any careful/experienced cyclist would/should be prepared for (and in fact expect) that the waiting motorist will make that left, regardless of the position of the bicyclist's head light. Same caution would appliy to being prepared to react to side traffic trying to pull onto the street during hours of darkness. The extra safety margin from a high mount head light is IMO insignificant when measured up to risk reduction from defensive cycling habits in these scenarios.
A high mounted rear light is an altogether different scenario and the higher the better. The cyclist can do little by defensive cycling to protect himself from a motorist especially at higher speeds who who can't see his lights from the rear due to traffic.