Active derailleur system and method

A method of operating a derailleur of a cycle, the method comprising:

• linking, by a chain, a cassette that includes a number of sprockets with a drive unit configured to drive the cassette;
• guiding the chain around the cassette by the derailleur;
• shifting, by a shift linkage of the derailleur, the chain between the number of sprockets of the cassette by moving the shift linkage in a gear change motion;
• maintaining a tension on the chain by a swing arm of the derailleur, the swing arm rotatable at a pivot assembly, wherein the shift arm extends from the shift linkage and is selectively rotatable relative to the shift linkage about the pivot assembly;
• unlocking, by a controller, a lock at the pivot assembly of the derailleur to control the tension on the chain during a gear shift, the lock configured to selectively lock the swing arm from rotating;
• and
• locking, by the controller, the lock when the gear shift is complete, wherein locking means the swing arm is prevented from rotating and the shift linkage is prevented from shifting the chain between the number of sprockets.

A cycle with a derailleur system at a rear wheel of the cycle, the cycle comprising:

• a cassette including a number of sprockets, the cassette disposed at the rear wheel;
• a drive unit powered by an electric machine and configured to drive the cassette;
• a chain linking the drive unit with the cassette;
• a derailleur, configured to guide the chain around the cassette, the derailleur including a shift linkage configured to shift the chain between the number of sprockets of the cassette and a swing arm rotatable at a pivot assembly on the shift linkage to maintain tension on the chain;
• a lock configured to selectively lock the swing arm from rotating;
• a frame of the cycle, wherein the derailleur is coupled with the frame, wherein the lock comprises a lock effector disposed between the frame and the swing arm;
• an actuator configured to engage and disengage the lock effector;
• and
• a controller configured to:
• determine whether shift conditions are met, where the shift conditions comprise requirements for initiating a shift between the number of sprockets including whether a brake signal is present;
• whether regenerative braking is active;
• whether pedal torque exceeds a first threshold;
• whether motor torque is above a second threshold;
• and whether a wheel speed of the cycle is above a third threshold;
• unlock the lock, by disengaging the lock effector through the actuator when the shift conditions are met;
• and
• lock the lock, by engaging the lock effector through the actuator when the shift is complete,
• wherein lock means the swing arm is prevented from rotating relative to the shift linkage so that the rear wheel is configured to drive the drive unit and the electric machine through the chain without creating slack in the chain.