Super-lightweight cranks for race engines are available with relieved counterweights, gun-drilled journals, etc. in an effort to reduce rotational weight. In addition, a popular modification involves bull-nosing and knife-edging the edges of the counterweights. Bull-nosing (radiused profile) and knife-edging (narrower chamfer profile) together create an “airfoil” cross-section of the end of the counterweight. The bull-nose profile is at the leading end of the counterweight while the knife-edging is at the trailing end, similar in concept to the cross-section of an airplane wing. In theory, drag factors, such as air resistance and oil cling, are reduced. For a street engine, it’s not worth the time and effort. Reserve this for race applications where (in theory) you’ll gain benefits with decreased air resistance and increased oil slinging. (Photo Courtesy Callies)