Suspension system of a vehicle and a shock absorber assembly of the suspension system, the shock absorber assembly includes a top mount and a jounce bumper. The jounce bumper includes a main body made of an elastic material, such as a foam elastomer or rubber and a fixing element made of a second harder material. The fixing element has a wall portion that extends around the outermost upper part of the main body and at least one elastic retaining area cooperating with a respective protuberance arranged in the top mount to fix the jounce bumper to the top mount. Between the outermost upper part of the main body and the fixing element there is a gap that enables the main body to expand radially also in the area covered by the wall portion of the fixing element when the main body is compressed during use.