Why a backflip is easier than a frontflip?

Now in the backflip, the very act of tucking the knees into the chest also starts the rotation. You don’t need anything else, really. That movement will tilt your pelvis and start the rotation too. In the frontflip, in order to start the rotation, you first have to “dunk”, curving your extended arms and your chest. Alternatively you can curve your chest and push your elbows backward (I saw this kind of technique used in free running). Only after that, once you started to rotate, you can tuck your knees into the chest, forming the ball and gaining speed.

The answer would be age 18.