The Invisible Bicycle Helmet..

The guaridan article states that the covering material tears on inflation so you would need a new cover as well as gas cylinder. It depends how much of the tech is in the cover.

Mmhmmm. Also the inflating balloon part would probably be damaged by repeated inflations. Although in the not-so-distant future there will probably be some smart material that re-seals onto itself.

Or they could use Velcro.

If I were being facetious, I'd say that it's in their interests to design a product that performs so well that users survive crashes and are sufficiently impressed to fork out another £350.