Graphic of Terms|A graphic with description of some terms that will be useful for the description of "aggressiveness".
Aggressiveness is not dependent upon a single dimension or measure of a razor. It depends upon blade geometry/angle, exposure, span, gap, weight, and most of all, the user.
Again: there are factors other than the blade gap size
that might make a razor seem more or less aggressive. Most notable is "blade exposure", or, the protrusion of the blade above a line tangent to the razor head and blade guard as they touch the face (see picture for more information and terminology).
[hide][top]Aggressiveness and Exposure
Aggressiveness of a safety razor can be thought of as the degree to which a blade is exposed to the face and beard, or conversely the degree to which the face and beard are not protected from the blade by the razor's safety features.
The two things that protect your face and beard from the blade are the razor's cap and the razor's guard. The cap and guard touch the skin while shaving and the blade is exposed to the skin between the two. Thus, the blade exposure can be described as the distance the blade protrudes past an imaginary tangent between cap and guard. The "gap" discussed above is not the same as the exposure as defined here, but larger gaps will tend to create larger exposures (and make it more possible for the skin to be caught inside the gap), given that the rest of the geometry stays about the same. So, the above measurements give an approximate ranking.
Another factor in aggressiveness might be the angle that the blade makes with that imaginary line. There is probably an ideal angle, usually stated as around 30 degrees from the face, but that might be different for different beards and maybe even different for different areas of the same beard.
One advantage of an aggressive razor may be that the user has more control over the angle at which the blade touches the skin.