Pedal-driven vehicle crank

A crank assembly for a pedal-driven vehicle, comprising:

• a first member that rotates about a crank axis of the pedal-driven vehicle;
• a second member rotationally coupled to the first member and configured to pivot clockwise and counterclockwise about the first member via a member pivot, the second member configured to receive a pedal at a pedal interface;
• a spring to bias the second member toward a default orientation relative to the first member when the second member pivots clockwise relative to the first member and to bias the second member toward the default orientation relative to the first member when the second member pivots counterclockwise relative to the first member;
• and
• a rotary sensor coupled to the first member, the rotary sensor configured to measure rotation of the second member relative to the first member.