The initial Energy of the biker is all potential because he starts from rest.
I chose the reference point to be at the bottom of the incline.
Friction acts against movement on the way down and takes away from the energy that can be converted to kinetic energy. By finding the work done by friction, we will know how much of the original energy was lost to friction, and how much will remain for kinetic energy.
We now know how much energy is taken away by friction. The remaining energy will be all in the form of kinetic energy at the bottom of the incline.
