Table 1.

The damages observed on the cyclist’s helmet.

Cause	Damages	Location	Details
Severe impact	Crushed surface	Rear left	1. 75 mm in diameter with small pits, produced by road aggregates compression 2. Crush depth of the flattened surface is 4.9 mm 3. Delamination between shell and liner
	Crack trajectory	Rear left	Five major cracks
	Localised shell buckling	Rear left-top	Localised shell buckling with scrapes
Moderate impact	Crushed rear end	Rear top	1. Crush depth is 6 mm 2. Delamination between shell and the liner
Mild impacts	Delamination	Rear right	1. Delamination between shell and liner 2. No obvious crush of liner
	Localised dents	Rear	Small pits on the EPS form and shell