A mower-conditioner for cutting and conditioning crop material, comprises a mower unit for cutting crop material and a conditioner unit that is configured to condition the cut crop material. A drive input is configured to receive a rotational drive from an external drive unit, and a drive transmission system is configured to transmit rotary drive from the drive input to the mower unit and the conditioner unit. The drive transmission system includes a continuously variable transmission (CVT) that transmits rotary drive between the mower unit and the conditioner unit with a variable speed ratio.