Originally Posted by skidder

Round metal tube frames were used in UCI races up until about 2000 (aluminum), and some aluminum bikes had aero-shaped frame tubes (Trek's "hydroformed" tubing comes to mind) but a lot of other features on bicycles have changed since the 1920s, too. You can still buy a metal-framed bicycle but its not going to have the cutting-edge components on it you'll find in more modern bicycles. For comparison, have you ever tried to drive a 1920s car versus a 2020 car? It's a world of difference. If today's cars were made like those of the 1920s very few folks would be driving them.