IV.2. Parts of a roller skate

Wheel

The wheels of roller skates can be put into three categories based on the following characteristics: diameter, hardness and profile. Their size can be between 45 and 145 mm in diameter. The larger the wheel, the faster it is, though it is also harder to manoeuvre (as the centre of gravity is higher and the frame is longer. Smaller wheels are slower, but easier to manoeuvre (as the centre of gravity is lower and the frame is shorter). The letter “A” indicates the hardness of the wheel. There are three types of wheels: soft (74A-78A), medium hard (80A-87A) and hard (88A-96A). If the wheel is soft, its heat dissipation is worse, so it wears out faster and “glides” more slowly, whereas hard wheels have better heat dissipation, so they wear out less and “glide” at a greater speed. Earlier, wheels were made of PVC, but today they use polyurethane. Skaters can find the diameter and hardness ratings on the side of the wheel. Its profile type is not indicated, but it is easy to notice when we lift the wheel to eye-level. There are wheels with rounded, elliptical and flat, rectangular profiles. A wheel’s profile determines the surface that is in contact with the ground. If the landing surface is larger, there is greater friction, which reduces speed. However, if this surface is small, the skate runs faster. The types of wheels necessary for different roller skates will be discussed later.

Bearing

A wheel contains two bearings. Bearings have two ratings: ABEC and ILQ. ABEC is a standard rating with a scale that uses the numbers 1, 3, 5 and 9. ILQ is the German rating, which uses the numbers 5, 7 and 9. The higher the rating number, the greater the manufacturer’s precision in making the bearing. Naturally, the precision and material of the bearing influences its speed, as well. Bearings with a lower rating are more stable and have greater lateral load capabilities, but are slower, whereas those with higher numbers are quicker, but wear out more easily and become useless under excessive lateral load.

Spacer

There are two types of spacers on a roller skate: the external and internal spacers. The external spacer is located between the frame and the wheels. Nowadays, these are built in the frames. The internal spacer sits between the two bearings. It has two types: 6-mm or 8-mm depending on the diameter of the axle. The spacers are only in contact with the rim of the bearing, and ensure unimpeded and proper rolling. Their quality and durability depend on the material, which can be plastic or metal.

Boots

You have to choose roller skates boots to be one size larger than your normal shoe size. For children, boots with adjustable size are also produced. Its soft lining absorbs vibration. One of the two types of boots is the bond, which is similar to ski boots and holds the ankle well. The other is the Viking, a low-top boot, which is suitable for covering long distances. Boots can be made of carbon fibre material, fabric and/or plastic. In the case of boots with bayonet closing, the frame can be unfastened.

Brake

In old-fashioned double-row skates, the brake was located in the front, at the tip of the boot. In the case of single-row roller skates, the brake is at the back, on the right side of the boot. It is important to note that its use is recommended for children, as adults are taught to stop safely with different techniques without using the brake.

Protective gear

Although protective gear is not part of roller skates, they are closely connected to the sport. The basic gear consists of wrist, elbow and knee protection pads and a helmet. In the case of different disciplines or branches, further special equipment may be added.