The Amalfitana cut into the cliffs from Positano to Amalfi — sea on one side, rock on the other.
Its tightest bends have a radius of about 19 m and its typical bend about 47 m. The angles are the physics of the corner: the lean a bike needs to hold that line at that speed. Real bikes lean a few degrees more, because a tyre is round. apex measures what you actually did.
Lean is measured by the phone on the bike or in the rider's pocket and checked against the corner itself: how fast the rider went and how tightly the road turned. More roads.