I've recently come across two unexpected and possibly revolutionary inventions for bicycles as the mode of transportation becomes a more and more viable way to commute around cities that are becoming increasingly dense.
The first is an "electric bicycle wheel", which fits on most bikes and turns any regular bicycle into a motorized rechargeable electric bicycle.
And the second invention is an "invisible" bicycle helmet. How it actually works came as a complete surprise to me, so I won't spoil it by describing. Just watch, it's amazing.
The Invisible Bicycle Helmet | Fredrik Gertten from Focus Forward Films on Vimeo.