A bicycle locker or bike box is a locker / box in which a single bicycle can be placed and locked in. They are usually provided at places where numerous cyclists need bike parking for extended times (such as during the working day or at university), yet where the bikes might otherwise get damaged or stolen (such as at public bus terminals).
Bike boxes are considered the highest standard of bike safety (better than locked compounds or simple bike stands) because they prevent not only theft, but also casual vandalism.
Lockers are usually either rectangular boxes or formed as triangles where the handlebars of the bicycle are on the wide side of the triangle. Triangle boxes can also be combined to form a rectangular box with two individual lockers, or arranged in a circular pattern around a centre point. Some rarer types are either upright like school lockers (which requires the bicycle to be suspended from a hook inside) or are stacked twice high, with some attendant difficulties in inserting and removing bikes in the top row.
Bike boxes are usually built with solid sides to protect against weather, vandalism and theft. However, problems encountered with this approach (such as being used by homeless people as sleepouts, or for the storage of things other than bicycles) have led to newer designs which encorporate windows or grilles through which inspection staff can see inside.
Bike box locks depend on whether the boxes are rented out on a fixed period basis, or whether they are first-come-first served. Those which are rented out for a set period of time usually come with a specific key. Those which are usable on a more casual basis either allow the door to be locked by a padlock brought along by the user, or provide a rental system that dispenses a key or code.
Statistics from the BART rail system suggest that the effective capacity of an on-demand locker bank is 5 times higher than a similar sized exclusive locker bank.