i was coming to work this morning, at a stop light i guy pulled up and said my rear sprocket was lose that it move before the tire moved. so at the next red light i stood up and let the clutch out and noticed the sprocket hub move about 1/4 of inch before the tire started to turn. so my question is should this be or do i need to pull the rear tire and tighten? as i was looking the sprocket it self is not moving but the hub the sprocket is attached to moves.