A mountain bike (MTB) or mountain bicycle is a bicycle designed for off-road cycling. Mountain bikes share some similarities with other bicycles, but incorporate features designed to enhance durability and performance in rough terrain, which makes them heavier, more complex and less efficient on smooth surfaces. These typically include a suspension fork, large knobby tires, more durable wheels, more powerful brakes, straight, extra wide handlebars to improve balance and comfort over rough terrain, and wide-ratio gearing optimised for topography and application (e.g., steep climbing or fast descending). Rear suspension is ubiquitous in heavier-duty bikes and now common even in lighter bikes. Dropper posts can be installed to allow the rider to quickly adjust the seat height (an elevated seat position is more effective for pedaling, but poses a hazard in aggressive maneuvers).
BMX, an abbreviation for bicycle motocross or bike motocross, is a cycle sport performed on BMX bikes, either in competitive BMX racing or freestyle BMX, or else in general on- or off-road recreation.
