Dirt bike

A trials bike, note lack of seat

There are several different types of off-road motorcycles, also known as dirt bikes, designed and specialized for specific functions. For off road use they typically, when compared to road going motorcycles, have:

• Light weight
• Long suspension travel and high ground clearance
• Simple, rugged construction with little bodywork and no fairing
• Large wheels with knobby tires, often clamped to the rim with a rim lock

Off road motorcycles are often specialized for a variety of off road motorcycle sports, notably;

Motorcross

• Motocross — A uniquely designed track of a variety of different obstacles where people compete to win the race. The motorcycles have a less than 2 gallon tank which makes them light. Their precise suspension travel allows riders to fly over jumps at high speeds. There are two different classifications of motocross classes. 250cc are usually two-stroke and 450cc are usually four-stroke. A rider chooses his/her bike depending on the preferences they prefer.

Rally bikes

• Rally raid, or Rallies — long distance racing, typically through deserts for long distances. Road legal machine (like enduro) but with significantly more fuel. Capacities tend to be larger, around 450 cc to 660 cc (two or four stroke), an upper limit is often imposed for rider safety.

Trials Motorcycles

• Trials — An extremely specialized form of competition focused on balancing skills and precision rather than speed. Thus low weight and quick power is the priority leading to small (125 cc to 300 cc) engines, often two strokes being used. Seats are unnecessary and affect the center of gravity so they aren't installed (sometime they are jokingly referred to as banana bikes due to the lack of a seat). Fuel is kept to a minimum so range is very limited.

Oval Track

• Track racing — High-speed oval racing, typically with no brakes, no suspension, at most two gears, fueled by methanol (not road legal machines).