With the advent of Electrically Pedal Assisted Cycles (EPACs), bicycles are becoming more and more technologically advanced, and active control systems are being developed to deal both with rideability enhancement and with energy management features. Within this context, this paper investigates the design of the control system for a continuously variable transmission, that allows a fine regulation of the transmission ratio and can thus improve the riding feeling with respect to a standard bicycle gear system. This control system is to be seen as the enabling step to design higher-level control systems that will allow to optimize the rider's effort in an EPAC, by designing a gear shifting policy which achieves the best trade-off between energy consumption and rideability. Experimental results are presented which witness the effectiveness of the proposed approach. (6 pages)