Roof racks, where the bike is fixed on the rear wheel and the fork front end, are unproblematic.
Race bikes with carbon fork front ends are an exception.
In addition, roof racks that fix the bike on the down tube are inappropriate. This may squeeze and damage the tube permanently.
Rear carrier, where the bicycle is fixed on the two wheels and top tube, are usually suitable for aluminum frames. The best way to transport the bike is in the car. This protects against theft and is more gentle to your bike.