Fulcrum Red Zone All Mountain Wheel The rims are class 21 lightened between one spoke & the other, so we have a rim that is strong but at the same light. Both the front & rear wheels have 24 stainless steel spokes with variable thickness 2.2/1.8/2, with reinforced head, distributed according to Fulcrum® 2:1 technology with double the number of spokes on the cassette side for the rear wheel & disc side for the front. This means getting the maximum performance both when pedalling & manoeuvring.