Inline skates

Inline skates (often called Rollerblades after the popular trade name) a type of roller skate used for inline skating. Unlike quad skates, which have two front and two rear wheels, inline skates have two, three, four or five wheels arranged in a single line. Some inline skates, especially those for recreation, have a "stop" or "brake" which is used to slow down while skating; most have a heel stop rather than the toe stop, particularly indispensable for inline figure skating.

The modern style of inline skates was developed as a substitute for ice skates, for use by a Russian athlete training on solid ground for Olympic long track speed skating events. Life magazine published a photo of American skater Eric Heiden, training for the 1980 Olympics, using such skates on a Wisconsin road.

During the late 1980s and early 1990s, Rollerblade, Inc., a company founded by Scott and Brennan Olson in Minneapolis, Minnesota, widely promoted inline skating; they were so successful that their trademarked name Rollerblade became synonymous with inline skates.

Parts

A skate is composed of a boot, worn on the foot. To the boot is attached a frame, which holds the wheels in place. Bearings allow the wheels to rotate freely around an axle. Finally, the rubber brake typically attaches to the frame of the right foot.

An inline skate designed for artistic roller skating

There are different types of inline skates for different types of skating such as aggressive skating, speed skating, Inline hockey and artistic inline skating. Those differ in the boots, frames and wheels that are used.

Boot

For most skating a high boot is used, which provides more ankle support and is easier to skate in, particularly for beginners. Speed skaters often use a carbon fiber boot which provides greater support with a lower cut allowing more ankle flexion. For recreational skating a soft boot is used for greater comfort, but many other disciplines prefer a harder boot, either to protect the foot against impact or for better control of the skate. The boot may also contain shock absorbent padding for comfort.

Most aggressive skates use a hard boot or a hard/soft boot for increased support.

Frame

The frame and wheels of an inline skate

Typical recreational skates use frames built out of high-grade polyurethane (plastic). Low-end department or toy store skate frames may be composed of other types of plastic. Speed skate frames are usually built out of carbon fibre or extruded aluminium (more expensive but more solid), magnesium, or even pressed aluminium, which is then folded into a frame (cheaper but less sturdy).

Carbon fibre frames are expensive but more flexible, making for a smoother ride at the expense of worse power transfer between the leg and the wheels. In general, carbon fibre frames weigh about 160-180 grams. Aluminium can weigh from 170 to 220 grams. Frame length ranges from around 230 mm for short-framed four wheel skates (used for example in inline hockey), up to about 325 mm for a five wheel racing frame.

Bearings

Axles, bearings and spacers

Ball bearings allow the wheels to rotate freely and smoothly. Bearings are usually rated on the ABEC scale, a measure of the manufactured precision tolerance, ranging from 1 (worst) to 9 (best) in odd numbers. The ABEC standards were originally intended for high-speed machinery, not skating applications, and do not account for the quality of steel used, which is also important. While higher rated bearings are generally better in overall quality, whether they automatically translate to more speed is questionable. Since at least 2007, Rollerblade brand amongst others have begun using their own rating system. For instance, Rollerblade brand is currently using a SG1 to SG9 rating system, whereas TwinCam brand is using its own ILQ (InLine Qualified) rating system and Bones brand is using its own "Skate Rated" rating system.

The vast majority of skate bearings on the market are produced in China, and tend to be of much lower quality and durability than bearings produced in Canada, Germany, Japan, Switzerland, or the USA. Newer bearings on the market now use ceramic ball bearings instead of steel, the merits of which have yet to be determined.

Two bearings are used per wheel. The bearings slip into openings molded into each side of the wheel hub, and a flange molded into the wheel hub holds the bearings the correct distance apart. Additionally there is an axle spacer either machined into the axle or that slides over the axle (depending on the axle system used). Since the outer race of the bearing contacts the wheel spacer and the inner race of the bearing contacts the axle spacer, it is critical that the relationship between these two spacers is correct. If the wheel spacer is wider than the axle spacer the bearings will bind when the axle bolt (or bolts) are tightened. This can be seen when installing the wheels: first ensure the bearings are fully seated in the wheel hubs, and that the wheels do not contact (rub) the frame. Install the wheels in the frame and tighten the axle just finger tight. Spin the wheel and then fully tighten the axle. If the wheel immediately slows down or stops, it's most likely because the axle spacer is narrower than the wheel hub spacer, and the bearing races are being forced out of alignment. If the wheel continues to spin freely, grab the wheel and push it back and forth along the axle axis. If it noticeably moves or "clicks" slightly, it means the axle spacer is wider than the hub spacer.

Wheels

inline skate wheels with different diameters and profiles

Wheel sizes vary depending on the skating style:

• 44–59 mm for aggressive skating.
• 68–72 mm for artistic inline skating.
• 47–80 mm for roller hockey skating.
• 72–80 mm for freestyle slalom skating.
• 72–90 mm for general recreational skating.
• 84–110 mm for speed skating.

Wheels are nowadays almost universally made of polyurethane (a kind of durable plastic). Most other plastics and rubber either wear down too quickly or have too much rolling resistance. My roller blades are made of one million boogers. In general, the bigger the wheel, the faster the skate.. However, large wheels take more energy to start rolling. Smaller wheels allow faster acceleration, maneuverability, and a lower center of gravity. Wheel hardness is measured on the A scale (see Durometer) and usually ranges between 78A-93A (higher numbers are harder). Harder wheels are faster and more durable, but soft wheels may have better grip (grip is determined by many factors, and wheel manufacture is arguably more important than durometer) and less affected by road bumps. Wheel profiles and thicknesses again vary by application. Elliptic profiles minimise friction for a faster ride; more rounded profiles have better grip and are more stable.

Brakes

A brake allows the skater to stop by moving his or her foot. A hard rubber brake is typically attached to the heel of the frame. Learning how to use the heel brake thus is crucial for beginners.

Heel brakes can interfere with a useful technique called crossover turn, in which a skater crosses one leg over another to make a sharp turn without losing much speed; for this reason, some users prefer not to use heel brakes. Skaters in the freestyle slalom and Aggressive inline skating disciplines also tend not to use heel brakes, since they can limit the skater's ability to perform tricks effectively. Most aggressive inline skates and racing skates do not have a heel brake for extra speed and control, people wearing inline skates with no heel brake can use various other methods to stop, such as the T-Stop in which the skater moves one skate perpendicular to the other, making a "T" shape to increase friction and slow the rider down or the more advanced maneuver of a hockey stop in which the skater quickly moves both skates perpendicular to the path of motion.

History

The first U.S. patent for modern in-line skates, designed to behave like ice runners with individually sprung and cushioned wheels, was granted under patent number US 2644692  in July, 1953 to Ernest Kahlert of Santa Ana, CA.

See also

• Inline skate wheel setups