A bicycle-carrying device for motor-vehicles comprises a support structure defining a main axis, and a plurality of legs carried by the support structure for abutment on the rear part of a motor-vehicle. At least some of said legs are orientable around said main axis. The device further comprises a plurality of arms carried by the support structure for supporting one or more bicycles, and a plurality of belts or cables associated with the bicycle-carrying device and each having a book member for engagement on the rear part of the motor-vehicle, for anchoring said bicycle-carrying device to the motor-vehicle. At least some of said legs have each a respective roll-up device for winding a belt or cable around a respective winding axis. Each roll-up device is arranged within an inner cavity of the respective leg with the winding axis located at a position spaced apart from said main axis.