h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

It is a common misconception that the more gears a bicycle has, the easier it is to ride. New owners of Mountain Bikes are often bitterly disappointed to find that, for a given climb, they have to put in just as much effort no matter what gear they select. Their legs have to generate either relatively few very hard turns or very many relatively easy turns. Whichever they choose they get just as exhausted. The solution therefore is not technological (throwing more gears at the problem won't help) but physical - exercise and conditioning win every time.

Well, they're easier to ride if you are climbing, that's for sure. If you define "easy to ride" as "able to maintain a steady cadence of 80-90 rpm," an ATB is probably easier to ride than a cruiser.