Self-contained bicycle helmet and molding process therefor

A method for constructing a bicycle helmet having impact attenuating components, comprising the steps of:

• blow molding a shell having inner and outer walls defining a sealable cavity;
• forming an access hatch in said outer wall;
• filling said cavity through said access hatch with an impact attenuating material, said filling step including filling said shell with an expandable material that fuses or hardens over a characteristic temperature range, said filling step further including adding a selected quantity of water to said cavity through said access hatch;
• and
• treating said helmet as necessary to cause said impact attenuating material to fuse, including maintaining said helmet within said temperature range for a time sufficient to permit said expandable material to expand, said temperature range being maintained by heating said water to form steam to expand said beads, said water being heated using microwave heating;
• and closing said access hatch with a plug.

A method for constructing a bicycle helmet having impact attenuating components, comprising the steps of:

• molding a shell having integral inner and outer wails defining a cavity;
• forming an access hatch in said outer wall to provide entry to said cavity;
• filling said cavity with beaded impact attenuating material inserted through said access hatch;
• closing said access hatch with a plug;
• and
• applying no heat to said helmet such that said beaded impact attenuating material remains in a beaded state in said cavity.