#1291: Shellmet

Today’s invention is a collapsible bicycle helmet.

It consists of an outer bag with hemispherical bulges moulded into it of different sizes.

Each bulge contains an aluminium boss bonded to a rubbery base. The bosses are of slightly different sizes so that they nest conveniently together when removed from the bag and fit into it for ease of carrying eg in a pocket.

The bosses’ rubber bases make contact with the wearer’s head and are held in place by a drawstring around the base of the bag.

In an accident, the bosses sustain damage and dissipate any impact loading across a wide area of the skull.


  1. A nice take on the folding helmet idea. How long would it take to put on your head though?

  2. Yes, I see your point.

    Ok. I want to allow the cups freedom to nest in one’s pocket, whilst also ensuring that they array themselves around the head properly. The bag idea is ok if the cups are retained at locations within it, but then it’s hard to see how there will be enough spare material to allow nesting. I might try bungees or a spandex bag, but these are subject to local stretching on impact with the road…bad idea.

    I think the best solution is probably to have a head-shaped leather bag (like an old-fashioned helmet liner). This would have holes into which the cups would each fit tightly. Each cup has a single hinge to the leather perimeter of its hole. This allows the cups to flop inwards, when the helmet is removed and the leather near the hinges to buckle outwards when the cups nest. The cups could click together when nesting to make for an easier process.

Comments are closed