What are the most effective methods for adjusting the pedal assist sensitivity on an ebike to ensure optimal emergency braking performance, and how do these adjustments impact the overall riding experience? Are there any specific settings or calibration procedures that can enhance the responsiveness of the pedal assist system during emergency stops, and what are the potential risks of over- or under-sensitivity in these situations? How do different ebike manufacturers approach pedal assist sensitivity calibration, and are there any industry standards or best practices that riders can follow to optimize their bikes performance? Additionally, what role do factors such as terrain, rider weight, and bike load play in determining the ideal pedal assist sensitivity settings for emergency braking, and how can riders balance these competing demands to achieve safe and effective braking performance?