The team of Professor Keon Jae Lee from the Department of Materials Science and Engineering, KAIST has developed a high performance flexible all-solid-state battery, an essential energy source for flexible displays (see paper in Nano Letters: "Bendable Inorganic Thin-Film Battery for Fully Flexible Electronic Systems").
In fact, this bicycle doesn't use any metal parts at all -- the solid tires are made of reconstituted rubber and a car timing belt is used instead of a chain.