No matter how smooth your pedal stroke, your power delivery will be peaky. The transfer of power from your legs to the circular chainring means that some parts of the pedal stroke deliver more power than others. The reason you notice Rotor Outer Aero Q Rings popping up on so many of the top pros' bikes is that the oblong shape counters this uneven power transfer to keep things smoother at the cranks. It also means less exertion to achieve the same speed and a reduction of the 'dead spot' that you notice in each stroke. The rings you see here are outer rings 50 , 52 , or 53 tooth. The 50 and 52 are compatible with 110BCD Shimano or SRAM cranks, while the 53 is compatible with 135BCD Campagnolo models. All work with 10 or 11 speed drivetrains.