The frontal area of the disc isn't that great.
If aero was just about frontal area, we'd all be riding 16mm Pianni rims from the 1980s, not 27mm wide Zipps. As soon as there's the slightest crosswind, a flat brake disc generates a lot of turbulence off both leading and trailing edges.
@gbj_tester started
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If aero was just about frontal area, we'd all be riding 16mm Pianni rims from the 1980s, not 27mm wide Zipps. As soon as there's the slightest crosswind, a flat brake disc generates a lot of turbulence off both leading and trailing edges.