The bike helmet with airbags reminds me of the airbag jacket worn by Y.T. the skateboarder in Neal Stephenson's "Snow Crash":

"She lets go of the handle and goes into free fall. At the same time, she jerks the manual release on her cervical collar and goes into full Michelin Man mode as tiny gas cartridges detonate in several strategic locations around her bod. The biggest one goes off like an M-80 at the nape of her neck, unfurling the coverall's collar into a cylindrical gasbag that shoots straight up and encases her entire head. Other airbags go off around her torso and pelvis, paying lots of attention to that spinal column."