Abstract: A bicycle helmet and bicycle helmet molding process provide an impact attenuating bicycle helmet/shell having the advantages of low cost, ease of manufacture, as well as ruggedness and durability. In preferred embodiments, a shell having inner and outer walls defining a sealable cavity is provided and an access hatch is formed in the outer wall. The cavity is fully or partially filled through the access hatch with an impact attenuating material. The helmet is treated if necessary to cause the impact attenuating material to harden or fuse or otherwise remain within the sealable cavity, and a plug is used to close the access hatch, thus providing a superior bicycle helmet/shell wherein the impact attenuating material is trapped within the shell portion of the product.