The distance needed for a cycling event to be considered
ultra-distance cycling or an
endurance race is far more vague than in
ultra running (any race longer than a
marathon) or in
ultra-triathlon (any race longer than an
Ironman Triathlon). Any
bike race longer than a
century ride, which is , is sometimes considered to be ultra-distance cycling; however, such events are relatively common, so using a longer distance to define the category is more useful, such as any race that is longer than , or even a double century, .