A track system for a vehicle seat, the track system comprising: a lower track having a track profile with a lower vehicle attachment surface and an upper surface extending in a longitudinal axial direction between a lower track forward end and a lower track rearward end and extending in a lateral direction between lower track side profile portions; a slide block comprising a first slide bar extending along the upper surface at a first lower track lateral side, a second slide bar extending along the upper surface at a second lower track lateral side and a cross web system connecting the first slide bar to the second slide bar, the cross web system comprising a central cross web portion, a forward cross web portion, positioned with respect to the longitudinal axial direction between the lower track forward end and the central portion, and a rearward cross web portion, positioned with respect to the longitudinal axial direction between the lower track rearward end and the central portion; a lower track to slide block fastening system comprising a central fastener (34, 74) fixing the central cross web portion relative to the lower track at least in the lateral directions and in the longitudinal axial directions, a forward fastener (36, 75, 76) fixing the forward cross web portion relative to the lower track in the direction away from the lower track and allowing movement of the forward cross web portion relative to the lower track at least in the longitudinal axial directions and a rearward fastener (38, 77, 78) fixing the rearward cross web portion relative to the lower track in the direction away from the lower track and allowing movement of the rearward cross web portion relative to the lower track at least in the longitudinal axial directions; and an upper track and a rolling bearing cage connected to the upper track, wherein the slide block supports the movement of the upper track and has end stops for the rolling bearing cage. a lower track having a track profile with a lower vehicle attachment surface and an upper surface extending in a longitudinal axial direction between a lower track forward end and a lower track rearward end and extending in a lateral direction between lower track side profile portions; a slide block comprising a first slide bar extending along the upper surface at a first lower track lateral side, a second slide bar extending along the upper surface at a second lower track lateral side and a cross web system connecting the first slide bar to the second slide bar, the cross web system comprising a central cross web portion, a forward cross web portion, positioned with respect to the longitudinal axial direction between the lower track forward end and the central portion, and a rearward cross web portion, positioned with respect to the longitudinal axial direction between the lower track rearward end and the central portion; a lower track to slide block fastening system comprising a central fastener (34, 74) fixing the central cross web portion relative to the lower track at least in the lateral directions and in the longitudinal axial directions, a forward fastener (36, 75, 76) fixing the forward cross web portion relative to the lower track in the direction away from the lower track and allowing movement of the forward cross web portion relative to the lower track at least in the longitudinal axial directions and a rearward fastener (38, 77, 78) fixing the rearward cross web portion relative to the lower track in the direction away from the lower track and allowing movement of the rearward cross web portion relative to the lower track at least in the longitudinal axial directions; and an upper track and a rolling bearing cage connected to the upper track, wherein the slide block supports the movement of the upper track and has end stops for the rolling bearing cage.