A brake assembly for exercise cycling apparatus comprises rotor means (2) with at least one pair of magnetic elements (4, 4') adapted to be rotated about a longitudinal axis (X) by a user who applies a driving torque thereon, stator means (3) adapted to cooperate with the at least one pair of magnetic elements (4, 4') to generate a resistance torque adapted to oppose the above driving torque, guide means (7) associated to the rotor means (2) to cause translation of the magnet elements (4, 4') along respective directions (d, d') having at least one radial component to cause variation of the resistance torque proportionally to the driving torque. The magnetic elements (4, 4') are reciprocally coupled to make the displacement thereof along directions (d, d') mutually dependent and with substantially the same length (l, l').