What are the key differences in techniques for handling gravel curves between high-speed and low-speed scenarios, and how do these differences impact bike positioning, body weight distribution, and braking strategies in each situation. Are there specific considerations for different types of gravel surfaces, such as loose, hardpack, or sandy conditions, and how do these factors influence the optimal approach to navigating a curve. Additionally, what role does tire choice and pressure play in gravel curve handling, and are there any specific skills or drills that can be practiced to improve proficiency in this area. How do riders balance the need for speed and control when approaching a gravel curve, and what are the most common mistakes to avoid in order to maintain traction and avoid losing control.