Which of the following is NOT a cause of hard steering?

Hard steering can often be attributed to factors directly related to the power steering system or components that affect steering effort. Low power steering fluid, for example, can result in increased steering effort because the hydraulic pressure needed for power assist is diminished. Similarly, a weak power steering pump may not provide sufficient hydraulic pressure, leading to difficulty in turning the steering wheel.

Worn wheel bearings, while they can affect the overall operation of the vehicle and potentially cause additional resistance in the suspension or steering systems, do not directly cause hard steering. Instead, they may lead to other symptoms such as noise, vibration, or play in the steering, but the act of steering itself typically remains manageable. Therefore, the presence of worn wheel bearings does not intrinsically lead to an increase in steering effort, making this choice the correct response to the question regarding what does not cause hard steering.