Abstract: An adjustable protective helmet for sporting activities comprising a first shell and second shell, having respective cooperating inner and outer overlapping portions extending transversely across the top portion of the wearer's head for connecting together the shells to form a bowl shaped shell assembly circumscribing the wearer's head. The shells are movable relative to one another in the overlapping portions to provide size adjustability of the helmet. The helmet includes a shock absorbing liner inside the shell assembly. The shell assembly comprises a ramp defined by a plurality of raised formations on the inside surface of the shell assembly, that is adjacent and facing a free edge of the inner overlapping portion thereby increasing the contact surface area between the liner and the shell assembly around said overlapping portions in order to reduce the concentration of force of an impact in the vicinity of the overlapping portions.