Halfdome is a bike helmet that folds in half so you can carry it in a backpack like a book. Two latches on the side of the helmet allow you to detach the top dome, turn it upside down, and drop it into the bottom ring. This reduces the helmet size by half, solving critical storage and carrying problems.  Fewer excuses for not wearing a helmet. An interlocking edge detail between the two halves of the helmet, combined with the two latches, provides a strong and safe joint between the top dome and bottom ring. Halfdome is a product concept from the Whipsaw Design Lab.