Why is it important to be in the proper gear before starting down a hill?

Being in the proper gear before starting down a hill is crucial for maintaining control of the vehicle and preventing damage to the transmission. When a vehicle is descending, it is subject to increased gravitational forces, and if the driver needs to shift gears during the descent, it can lead to stress on the transmission system. This stress arises because the vehicle's momentum will be higher when going downhill, making it more challenging for the transmission to engage smoothly. Being in the correct gear, typically a lower gear, allows for engine braking, which helps control speed without relying excessively on the brakes. This aids in preventing overheating of the brakes and ensures safer descents.