If you're just doing partial, the doorknob will probably hold. I'm about 200 lbs (~90 kg) and have attempted partial a few times (some were practice runs, some were serious with the intent to die but I always pussied out). My doorknob has showed no signs of damage or distress during any of the attempts; though keep in mind my house is fairly nice and was built a year ago, so maybe the doorknob is stronger than most. If you can, I'd recommend attaching the rope to the doorknob on the opposite side of where you intend to be, throwing the rope over the door then jamming it with the door against the frame. That way, the door frame sustains some of the force and the doorknob doesn't have to bear the full load.