What is a bike marathon called?

Answer 1

There is no official term. The nearest you could get would be "bikeathon" and to be roughly equivalent to a marathon, it would need to be at least 100 miles or 160km.

A marathon is a running race, named after the distance reputedly run after a battle in ancient Greece to deliver a message to Athens that the battle at marathon (25 miles/40kms away) had been won. The race was introduced for the first time at the modern Olympics and then standardised to 26 miles & 385 yards (42.195km) after 1921.

The term marathon is often misappropriated to uses other than running, to indicate anything long or demanding of endurance. All of these other uses, including biking, have no standard definition and are slang or common usages. A bike marathon has no official name because there is no bike marathon distance.