The sole function of the flat of the blade is to glide straight forward and straight backward. To be on the flat you must stand so that the skate is upright (blade perpendicular to the ice). You will be gliding equally on both edges and in a straight line.
Edges have multiple functions.
Blade edges are designed to cut into the ice. Because blades are rockered (have a radius) they are also designed to curve. Therefore, edges have two functions:
The pushing skate is the one that must grip the ice to set up a powerful push. The gliding (directional) skate is the one that must be on a strong edge so that you can travel tight curves. These two functions are totally separate and distinct from one another. One skate digs in to push while the other digs in to travel a curve or circle.
It may be said that the Wheels Aluminium Hub is the heart of the wheel and certainly has a big job to carry out. Firstly, the hub provides an anchor point for the spokes and holds the bearings in place so the wheel can spin. Secondly, the rear hub holds the cassette or sprocket which transmits the forces from pedalling via the hub body to the spokes ultimately propelling the rider forward. Lastly, the hub provides a sound mounting point for the brake rotor and an anchor point- through the use of quick release or bolts- to keep the wheels and frame attached.
At the very cheapest end of the industry, hubs are made from three pieces of steel – two pieces for the spoke flanges and one tube in between. In the middle price range sits one piece aluminium hubs. These can be machined or forged from a chunk of alloy. Small production runs and intricate shapes rely on the machining process whereas large production runs and smooth, flowing shapes work better with the forging process. Many of the high end hubs return to the three piece construction paradigm; often with exotic dissimilar materials for the flanges and the hub centre tube.
Another area where hubs fall into two camps is in the bearings. Most hubs have a cartridge bearing pressfitted into the central tube. If something goes wrong with the bearings, they can be fairly easily replaced with an entirely new unit (including hybrid- and full-ceramic options). The more traditional bearing option is the cup and cone design. Inside the hub shell is a steel cup that holds the ball bearings, while on the axle is a cone that holds the balls against the cups allowing the load to get from axle to hub shell. Cup and cone hubs are more easily adjusted and repaired than the cartridge bearing option, however, once the cup is damaged you are usually looking at a replacement hub.
