A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle. Fixed-gear single-speed bicycle is a subcategory of the single-speed and the most basic type of bicycle. A fixed-gear bike (also called a fixed-wheel bicycle or fixie) does not have a freewheel mechanism to allow coasting. [Wikipedia]