An electric bicycle derailleur control system is basically provided with a derailleur, a detecting device and a controller. The derailleur includes a chain guide and an electrical actuator. The chain guide is configured to displace a bicycle chain. The electrical actuator is operatively coupled to the chain guide to displace the chain guide. The detecting device is configured to detect information related to a reaction force of the bicycle chain. The controller is configured to control the electrical actuator in accordance with detected information.