If you are after low maintenance drivetrain, forget the derailleur, you will be looking at Single Speed or Internal Hub gears, like Shimano Alfine, Rohloff Speedhub and Kindernay XIV. There are also other alternatives like the Pinion Gearbox. At OLSEN HQ we have developed our bikes to fit chains and derailleurs, but to work even BETTER with Gates Carbondrive.

Experience from the REAL World:
Chains have links that rust, trap mud, water, and grit, and must be oiled. Remember that a derailleur chain drive system has more than 98.6% losses with its crude forever changing chainline. Gates Carbon Drive runs clean and sheds water, mud, and grit. Is there a winner to the belt vs chain test?? That depends on whether you are looking at results from the Lab or from the Real World. In real-world conditions, belts are the clean and simple winner.