Which statement is a commonly cited disadvantage of disc brake systems?

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Disc brake systems rely on hydraulic clamping of pads to the rotor, without the wedge-action that amplifies braking force in drum brakes. That wedge-like self-energizing effect occurs in drums because the expanding shoes press against the drum in a way that creates additional braking force as the wheel rotates. Since disc brakes lack this geometry, they do not gain that extra force automatically, so more hydraulic pressure is needed to achieve the same braking effect. This is why not self-energizing is commonly cited as a disadvantage of disc brakes.

In contrast, the other statements describe advantages or less accurate claims: discs actually dissipate heat very well, which reduces fade; they tend to be quieter than drum brakes; and while many parts can be more costly, saying they are lower in cost in all cases isn’t correct.