We investigated the mechanical properties of single chains of dendronized polystyrenes with dendrons of generation 1 to 4 spin coated on the basal plane of graphite. A scanning force microscope was used both to image the chain relaxation upon annealing and to manipulate single chains directly. The two approaches show that conformations for higher dendron generations chains are inherently trapped at room temperature. This behavior is attributed to a glassy state of single dendronized polymer chains. Upon annealing, the chains relax and orient quite perfectly along the axes of the substrate.