The racing bike of yesteryear is almost aesthetically and compositionally nothing like those that exist today. In fact, judging from the below GIF, which Dominik Lenarczyk compiled from a series of still images posted on Zeit.de last year, the only real constant is that every bike has two wheels and a seat. But the size and materials of those wheels is different, as is the seat, which changed in shape, size, material and where it sits compared to the frame. The transformation is really kind of cool. Take a look.

(Dominik Lenarczyk via Reddit)

(H/t: Reddit)