Here are two examples of "innovations" relating to the bicycle drivetrain which were already known more than 100 years ago. Both are taken from a German Encyclopedia (Kramer's Konversations Lexicon) published in 1907.
The illustration shows the "Gritzner" chainless bicycle, which according to the text shown below has the advantage of requiring very little maintenance despite being slightly more heavy and giving a more harsh feel on the pedals.
The following picture shows a detail of the "Goricke" shaft drive with bevel gears.
This was used in an early bicycle, with the so-called "Vietor" cranks:
The source of the above illustration is "Fahrrad & Radfahrer" by Wilhelm Wolf published by Otto Spamer Verlag in 1890. It was reprinted in 1988 by Harenberg, ISBN: 3-88379-106-1.