The banked turn of a velodrome: 42–45 degrees on a 250-metre track, around 32 on a 333-metre one. Too little speed is the danger there, not too much.
The physics are simple: at speed, centrifugal force pushes you outward while the banking pushes back. With enough speed the two add up to a single force acting perpendicular to the track surface — you sit squarely in the turn. Let the speed fall too far and that balance tips, and you slide down towards the inside edge. Which is why the biggest thinking error on a first banked lap is wanting to be slow and careful. Hold the target speed your coach gives you, even when going faster runs against every instinct. Read the lines: black defines the official lap distance, red about 90 cm above the inner edge marks the sprinter's line, blue separates the banking from the flat inner apron. What often goes unnoticed: velodromes are built 10 to 15 degrees shallower than pure race physics would demand — otherwise the track would only be rideable at one speed.