Originally Posted by
mechBgon
Another problem with reflectors is that at closer ranges, the reflected light from the non-driver's-side headlight isn't coming back towards the driver. It's coming back towards the passenger. So what happens when the driver's-side headlight is burned out...? Yeah, reflector effectiveness takes a plunge at closer ranges. Unfortunately there are a lot of cars in my area with only one working headlight.
This is actually not a problem. A bike reflector has 2-3 facets that are aimed at slightly different angles, I think the official requirement is 30 degrees between each facet. Even if the reflector has a single facet, the passenger-side-only headlight drops the 3-degree observation angle at about 100 ft.
Car headlights aren't that directional either. The typical spread is 30-45 degrees to either side, and there's plenty of weak scattered light that spreads almost up to 90 degrees from parallel. Even the weak scattered light makes a reflector visible from close range.
However, it's good to be visible: Even the poorest kind of reflective tape/vinyl is visible to about 300 ft or a bit further. Applied around a frame tube, it becomes a 360-degree reflector that's visible in the scattered light from a single headlight.