A beach cruiser bicycle converted into a
mountain bike, and the origins of
mountain biking in general. From the early 70s, when pioneering BMXers who outgrew their 20-inch bikes started riding and modifying beach cruisers, as road bike wheels were too narrow and slick to work well in the dirt. Usually distinguishable by the round frame(most mountain bikes are boxy), BMX-style bars, knobbly
mountain bike tires and coaster brakes instead of modern pinch or disc brakes.