16 lux is going to be a very weak light even if it's well focused. If you're riding in low/no light conditions, it will be enough to see with after your eyes adjust. For city riding with all sorts of light pollution, you'll want something stronger; I'd suggest 25 lux at the least.

My 2 lights are rated 80 lux and 60 lux, and they're sometimes used for 12+ hours of night riding at a time.