A crank assembly for a pedal-driven vehicle includes a first member, a second member, and a rotary sensor. The first member rotates about a crank axis of the pedal-driven vehicle. The second member is rotationally coupled to the first member and is configured to pivot about the first member via a member pivot. The second member also is configured to receive a pedal at a pedal interface. The rotary sensor is coupled to the first member and configured to measure rotation of the second member relative to the first member.