Much has been said about the shape, contour and function of bearing edges, but it is not nearly as complicated as many manufacturers have tried to make it out to be. Essentially there are three elements of a bearing edge that alter the sound and performance of the drum.
Head to shell contact
As a drum head is tensioned down onto a drum, the part of the shell that actually comes in contact with the drumhead, known as the outer edge, determines how much drum head vibration is transferred into the Shell. The wider the outer edge is cut, the More the drum Head will come in contact with the drum shell. A wider outer edge will cause the apex of the bearing edge to be moved further to the center of the shell wall, while a very narrow outer edge will cause the drumhead to only rest on the outermost area of the shell, which causes the drumhead to have very little contact, and will cause very low amounts of sympathetic vibration to transfer from the drumhead into the drum shell.
The bearing edge apex can either be sharp, blunt or even dead flat. A wide, flat apex will mute the high high frequency tones emitted by a drum head, where as a sharper apex will allow the drumhead to vibrate more freely. If you are going for a dark sound, a flatter apex is recommended, but for a ringy tone, a sharp Apex is recommended.
Bearing edge angle
There are several very educated opinions about the angle of the outer edge of a very edge some say 30°, others say 45°, while still others swear by a round over. It has been my experience that the outside angle of a bearing edge plays a very little role in the tone of the drum. but rather it is how wide the outer edge is that determines the amount of sympathetic vibration transferring into the drum shell. Round over bearing edge causes more head to shell contact, and so will make the sound of a drum warmer. But whether it's a 30 or 45 does not matter when compared side-by-side.
The inner edge plays absolutely no role in the tone of the drum
categorically there are five different types of edges
The 10/90 double 45 which produces a bright and Ringy tone. Also known as the California cut it is the bearing edge that is most frequently used especially in entry level drums.
The 50/50 double 45 which creates much head to shell contact, while having a sharp edge. This creates a full range drum that is capable of producing the lowest frequency and the highest frequency possible for any given drum, making it the most versatile and sensitive of all edges. DW drums calls this cut "ESE", or rather the enhanced sound edge.
The 30/70 outside round over, with an inside 45, creates a warm and ringing tone but with minimal head to shell contact. this is the bearing edge that made Gretsch drums great, for that great Gretsch sound.
The 50/50 outside round over and inside 45 which places the around apex in the center of the shell which heavily mutes the high frequency vibration of the drumhead. get that 70 sound of dark loud boom on toms and bass with this cut.
The 50/50 outer around over and in around over with a flat blunt apex which heavily mutes the high-frequency town basically makes your snare sound like a baseball bat track or your bass drum sound like deep and punchy. Pearl exclusively uses this cut on their bass drums to make them sound punchy and powerful.
I hope this clarifies much of the confusion of bearing edges. If you have questions, send us a message in the contact us section.