Output
Luminous flux given out by a bicycle headlight (see "Type"); in models with adjustable brightness, usually, the maximum value is indicated.
The
higher the luminous flux, the brighter the headlight and the greater the illumination range (see below). On the other hand, this characteristic significantly affects the dimensions, weight and cost of the flashlight, despite the fact that high brightness is not always required — for example, for episodic trips along well-lit city streets, a powerful flashlight is not needed. Therefore, it is worth choosing a bicycle headlight according to the luminous flux, taking into account the features of the planned application; specific recommendations for different cases (city, highway, rough terrain, etc.) can be found in special sources. Also, do not forget that the actual lighting efficiency depends not only on the brightness, but also on the shape of the light spot.
Max. operating time
The longest time of continuous operation without replacing or recharging the power source, provided by a bicycle headlight (see "Type") in constant light mode (if there is a flashing mode, the operation time is usually longer, but it cannot be called the main one). This item indicates the value for the most economical format of operation, at minimum brightness; therefore, the actual headlight run time will generally be lower than advertised. It is also worth considering that many replaceable batteries (see "Power") are available in different capacities and have different durability — which means that battery life will also depend on the quality of the batteries. At the same time, this indicator is quite suitable for evaluating bicycle headlights and for comparing them with each other.
Max. brightness operation time
Bicycle headlight battery life at maximum brightness (see "Type"). This indicator is closer to reality than the maximum operating time (see above): in fact, it indicates the time that the flashlight is guaranteed to be able to work without replacing or recharging the battery. However note that some batteries (see "Power") can be produced in different capacities, and the manufacturer usually indicates the operating time for the most capacious (and expensive) batteries.
