Aerocrank is short for aerodynamic crank. In sports, aerodynamics refers to the behaviour of the athlete or the sports equipment in the wind. This resulting air resistance in the airstream counteracts the movement of the athlete. Since the air resistance has a significant influence on the speed of the cyclist, it is attempted to offer the air resistance as small an attack surface as possible. For this purpose, some bicycle parts can be replaced by more aerodynamic add-on parts. This also automatically improves the aerodynamics of the wheel and a higher speed can be driven with the same effort.
This is also the case with the aero crank, which has a minimal change compared to conventional cranks, but since every minimal change is noticeable in cycling, this change generates less power. An aero crank thus helps to minimize air resistance in order to be able to ride at higher speeds.