Wire activated rim brake system for a rollator partly positioned inside a rollator frame characterized by comprising: a brake housing positioned close to a wheel of the rollator and inside the rollator frame, wherein the housing comprises an entry opening and sliding surfaces oriented at a right angle to the rotational axis of the wheel, a brake assembly to be positioned in the housing comprising: a sliding section adapted to slide along the sliding surfaces inside the housing when the brake system is activated, and adapted to enter into position through the entering opening, a brake section extending at a right angle from the sliding section and protruding through the entry opening when the brake assembly is positioned inside the housing, and a brake pad fastened to, or molded in one piece with, the brake section, a brake cover comprising a cover gap allowing movement of the brake assembly, wherein the brake cover is covering the brake assembly and is fastened to the frame, a brake path on the inner rim of the rollator wheel which is parallel with the rotational axis of the wheel, and separated from wheel structures such as spokes in a direction parallel with the rotational axis of the wheel and wherein the brake pad is adapted to engage the brake path when the brake is activated, and a brake wire connected to a brake lever, wherein the brake wire is fastened to the sliding section of the brake assembly, wherein a return spring mounted onto the brake wire pretensions the brake pad away from the brake path. a brake housing positioned close to a wheel of the rollator and inside the rollator frame, wherein the housing comprises an entry opening and sliding surfaces oriented at a right angle to the rotational axis of the wheel, a brake assembly to be positioned in the housing comprising: a sliding section adapted to slide along the sliding surfaces inside the housing when the brake system is activated, and adapted to enter into position through the entering opening, a brake section extending at a right angle from the sliding section and protruding through the entry opening when the brake assembly is positioned inside the housing, and a brake pad fastened to, or molded in one piece with, the brake section, a sliding section adapted to slide along the sliding surfaces inside the housing when the brake system is activated, and adapted to enter into position through the entering opening, a brake section extending at a right angle from the sliding section and protruding through the entry opening when the brake assembly is positioned inside the housing, and a brake pad fastened to, or molded in one piece with, the brake section, a brake cover comprising a cover gap allowing movement of the brake assembly, wherein the brake cover is covering the brake assembly and is fastened to the frame, a brake path on the inner rim of the rollator wheel which is parallel with the rotational axis of the wheel, and separated from wheel structures such as spokes in a direction parallel with the rotational axis of the wheel and wherein the brake pad is adapted to engage the brake path when the brake is activated, and a brake wire connected to a brake lever, wherein the brake wire is fastened to the sliding section of the brake assembly, wherein a return spring mounted onto the brake wire pretensions the brake pad away from the brake path.