Learning how to use and control your edges is important in helping you become an efficient and confident skater- in fact, proper use of edges is paramount to being a great skater. You all hear me many times tell you to use your edge to push harder or to use your edge to skate a curve or make basic turns, ie. forward/backward, or more advanced turns, i.e.. three turns or mohawks. Let me take the time to explain what a skating edge is and its importance.
A figure skate blade can be compared to as a thick sharp knife having two edges- inside and outside. The inside edge is the blade that’s inside (between) your legs and the outside edge is obviously, the blade on the outside. The groove on the bottom of the blade, which is called a hollow, creates these two sharp precise edges.
In figure skating, there are a total of eight edges. Each skate has two edges and can move in a forward and backward direction so that results in four edges. Since you have two feet, there is a total of eight possible edges (right/left forward inside/outside edge and right/left backward inside/outside edge).
When you skate on both edges (or on a flat of the blade), it helps you glide straight. However, you won’t be able to go far and push on a flat edge because it’s the dullest part of the blade. So, it is always good to skate on an edge and never be on both edges or on a flat. Unlike walking or running, skating using edges is a learned skill and it is important to know how to use the edges properly to skate. The edges are what cuts into the ice to give your skates a grip so you can push and move. Besides pushing, the other purpose of the edge is to help you glide on a curve. When your skates dig into the ice with your edge, you can make curves and/or turns. The deeper the edge, the sharper your curves and turns are. This is most important not only in figure skating but hockey as well.
Here’s a good example of a deep left backward outside edge I was executing while also achieving fluid knee bends and change of lean and flow as I skated the Rocker Foxtrot.
To learn how to get an edge, you must lean your ankle, knee, leg, boot, and blade inside/outside to form an angle to the ice while also maintaining your balance. To have balance, your upper body must not lean while only your lower body does. It will take much practice to learn this skill and you may fall a lot but once you master learning how to skate on an edge you will see how much faster and easier it is to move across the ice.
Source: https://weekendwarriorshockey.com/how-sharp-should-my-skates-be-blade-hollow-demystified-2/
Lastly, you’ll hear the words, radius of hollow and radius of blade, when one refers to a figure skate blade. I’m not going to spend too much time explaining these terms because it can get very technical; however, I will try to give an overview so you have at least a basic understanding of these terms.
Radius of Hollow -
Source: https://www.researchgate.net/figure/Skate-blade-radius-of-hollow-ROH-frontal-view-Units-for-the-25-50-and-75-is_fig2_249956702
The length running between the two edges on a blade or the curve that’s carved into the bottom of the blade is the hollow. This shape is created by grinding the blade with a sharpening wheel.
The size of your blade hollow has a significant impact on how you skate. You can have a deep or shallow hollow depending if you want more or less edge. The depth of the hollow is determined by the radius. A smaller radius means a smaller circle which creates a deeper hollow, making the blades feel sharper and have more edge (or more bite). The two diagrams that I’ve attached best illustrate the radius of hollow.
A normal hollow is generally 1/2” to 1” (most beginners are 3/4” to 1”). My dance blades have a deep 3/8” hollow (most ice dancers have 7/16”- 3/8” hollow) because it’s critical for me to make sharp, clean, and deep edges and turns. The only drawback with a deep hollow is that you don’t get as much speed and so you have to work harder to get more glide. Contrary, my figure skate blades have 1/2” hollow which gives me less sharp feel and edge but allows for more glide and speed. It’s always an adjustment for me switching back and forth to these different skates but its what’s appropriate and required for these skating disciplines. Speed skaters’ blades are pretty flat or have almost no hollow because they need maximum glide.
A blade radius is the curvature of the blade from heel to toe or front to back (often referred to as the rocker) and determines the amount of the blade touching the ice. The flatter the blade curve will offer more speed and stability.
As your skating level changes, you may require a different radius of hollow so you’ll need to experiment and find the measure which works best for you