That's not really how deformation works. You have elastic deformation when a force is applied that doesn't cause strain that exceeds the elastic limit, if you stay in this region any deformation returns back to the undeformed state once the force is removed. If you exceed that limit you get plastic deformation, that is 'permanent' deformation. You also have deformation from fatigue which occurs from forces being applied below the elastic limit, but the strain is applied and then removed, reapplied, and on and on. Eventually there is fatigue failure, but this only occurs from the force being applied and removed repeatedly, if the force is applied and not removed there wont' be fatigue failure, and since you're below the elastic limit there is no plastic deformation. ... so on to the point, the force from a bike hanging is well below the elastic deformation limit, and the application of force doesn't really fall into fatigue territory ... so no worry about deformation over time