Driving a motorcycle in heavy rain requires **reducing speed** and even stopping if necessary. This is because rain affects visibility and tire grip on the pavement, which increases the braking distance.

- **Reduced visibility:** Heavy rain makes it difficult to see the road clearly, which can lead to dangerous situations if speed is not adjusted.

- **Tire grip:** When it rains, tires have less grip, especially during the first drops that mix with dust and grease, forming a slippery mud. This is even more critical for motorcycles, which are less stable and more fragile than other vehicles.

- **Braking distance:** With less grip, the vehicle needs more space to stop. Therefore, it is crucial to moderate speed and maintain a greater distance from the vehicle in front.

In summary, when driving a motorcycle in heavy rain, it is essential to **moderate speed** to ensure safety and avoid accidents.