Answer:
The main energy transfer is the transfer of potential energy (the potential to have energy due to position to kinetic energy (energy from movement).
Explanation:
At the top of the hill, the bike has very little kinetic energy and very high potential energy. As the bike goes down, the kinetic energy increases and the potential energy decreases. The bike has the least potential energy at the bottom of the hill. The higher up the bike is, the more potential energy. The faster the bike is moving, the more kinetic energy.