What is the typical braking force distribution between the front and rear brakes during a straight-line emergency stop on dry asphalt, and why?

1. 100% rear brake / 0% front brake, because the front brake must never be used on a motorcycle
2. Approximately 70% front / 30% rear (or up to 80–90% front), because dynamic weight transfer shifts motorcycle mass forward onto the front tire contact patch
3. 50% front / 50% rear under all braking conditions regardless of deceleration rate
4. 10% front / 90% rear to prevent front tire wear