It’s very important to know what length your current crank arms are when buying a new power meter. For example, if you are buying a left side crank arm such as a Stages or 4iiii, you need to be sure you get the correct crank length so that your left crank arm is the same length as the right. Or, even if you are buying a new power meter crankset and are changing both arms, you still need to know what size your current crank arms are so you know what size to buy. Your crank arm length should be stamped on the inside of the left crank arm, usually near the pedal end. If you can’t find it, please let us know so we can assist you.