Bike components include brakes, wheels, chains, shifters, crankset, bottom brackets, and derailleurs, forks, seats, and cassettes.
The most significant trend in bike drivetrains over the past five years has been the movement toward wide-range drivetrains with a single chainring.
Commonly referred to as a ‘1x’ (one-by), this arrangement has been popular on downhill mountain bikes for years, where large gear ranges aren’t needed and chain security (that is, no dropped chains) is very important.