Inline skates

Inline skates are boots with wheels arranged in a single line from front to back, allowing a skater to roll along on these wheels. Inline skates are technically a type of roller skate, but most people associate the term roller skates with quad skates, another type of roller skates with a two-by-two wheel arrangement similar to a car. Quad skates were popularized in the late 19th and early 20th centuries, while inline skates became prominent in the late 1980s with the rise of Rollerblade, Inc., and peaked in the late 1990s. The registered trademark Rollerblade has since become a generic trademark due to its popularity. To this day, "rollerblades" continues to be used in everyday language to refer to inline skates.

Urban skates

Hockey skates

In the 21st century, inline skates come in many varieties, suitable for different types of inline skating activities and sports such as recreational skating, road skating, street hockey, speed skating, slalom skating, aggressive skating, and vert skating. Inline skaters can be found at traditional roller rinks, street hockey rinks, skateparks, and on urban streets. In cities around the world, skaters organize urban group skates. Paris Friday Night Fever Skate (Randonnée du Vendredi Soir) is renowned for its large crowd size, as well as its iconic +10 mile urban routes. Wednesday Night Skate NYC is its equivalent in New York City, also run by volunteers, albeit smaller in size.

History

Development of wheeled skates

The history of inline skates traces back to the origin of ice skates in prehistoric times, with runners made from animal bones. Steel blades eventually replaced bone runners in the 13th century, with the Dutch sharpening blade edges for better purchase on ice for propulsion. Since then enterprising inventors have attempted to make boots that could similarly glide on non-ice surfaces, with wheels.

In 1760, John Joseph Merlin, a renowned clock-maker, musical-instrument maker and inventor from Belgium, experimented in London with "skaites" that "ran on wheels". This was the first recorded wheeled skates. Written records left no drawings nor descriptions of wheel configurations, however.

In 1819, Charles-Louis Petibled from France filed the first known patent on wheeled skates. Three wheels in a single line, mimicking a steel blade, were integrated into a wooden foot stand with leather straps. Two wheels sat under the ball of the foot, while one wheel was positioned under the heel. A copy of Petibled's wheeled skates are on display at the National Museum of Roller Skating, in Lincoln, Nebraska, USA.

5-wheel Volito skate - 1823

In 1823, Robert John Tyers from London was granted a patent for his skates with five wheels in a single line, again mimicking a steel bade. This novelty skate was popularized in London as "Volito" (to fly about, in Latin). A hand-colored print from 1829 in the British Museum depicts a satirical scene where men wearing Volito skates escape chase by men on boots. The National Museum of American History has a Volito skate in its collections. The main body of the skate is called the stock (or foot stand), and is meant to be attached to the bottom of a shoe. A frame with two wheel-mounting sides is secured to the stock. This skate employs a large wheel in the middle, and progressively smaller ones towards the front and the rear, creating a rockered wheel setup that allows skaters to execute turns more easily.

Up to this point in history, in 1823, "roller skates" as a term was not yet used. Inventors simply referred to their contraptions as wheeled alternatives to ice skates. All known novelty skates had wheels aligned in a single line. Skates were simply assumed to have a single runner, whether a steel blade on an ice skate, or a row of wheels on a wheeled skate. This state of affair continued through 1960.

Development of roller skates

Usage stats of various skating terms including "roller skates", before and after 1860

Around 1860, wheeled skates started to become more popular. Patents on a wide variety of wheeled skates were issued. The configuration of wheels started to depart from previous single-line arrangements. Many of these early patents were titled "roller-skate" or "parlor skate". Indeed, the Oxford English Dictionary dates the earliest printed use of the noun roller skate to 1860. Then, starting in 1870, the popularity of roller skates skyrocketed. Within a decade the term "roller skates" entered the popular lexicon.

Shaler skates with rubber rings - 1860

In 1860, the US Patent Office granted Reuben Shaler the first US patent on roller skates, titled "Wheel-Skate", with an accompanying drawing labeled "Parlor Skate". The four rollers (wheels) formed a straight line, and were mounted by pins on two side pieces of a hanger that we would now recognize as a frame of a modern-day inline skate. The key innovation was the flexible rubber rings he mounted on 4 metal roller cores. This allowed his roller skates to gain better purchase on carpeted floors.

2-wheel Anderson skate - 1861

In 1861, Albert Anderson was granted a US patent on "Improvement in roller-skates". The accompanying drawings titled "Parlor Skate" showed a two-wheeled skate, with a small wheel under the heel, and a much larger wheel in front of the toes, reminiscent of penny-farthing bikes. The large front wheel overcomes oncoming obstacles, preventing skater from falling froward. The stock (or foot stand) is inclined forward, with a raised heel section. This is not dissimilar to how some modern-day hockey, freestyle and speed skates pitch a player leaning forward by default, giving a skater greater stability and stronger strokes.

4x2 Pennie skate - 1861

In 1861, Henry Pennie was granted a US patent titled "Roller-skate", where its drawing titled "Parlor Skate" showed a stock supported by two rows of wheels, with 4 wheels on each row, totaling 8 wheels per skate. In the patent specification, Pennie explained that his key innovation was the two rows of wheels. This set his skates apart from all previous roller skates that attempted to emulate ice skates with a single, centered runner. Pennie reasoned that two rows of wheels provided increased support area for better balance, without materially incurring greater friction. Beginners would learn with two rows of wheels, for its balanced footing. Skillful skaters would move the two rows of wheels increasingly closer to each other, using different widths of washers as spacers, until they graduate to a single row of wheels. Pennie's skate, too, had two side plates secured to the stock, forming what continues to be known as a "frame" today.

2x2 Plimpton skate - 1863

In 1863, James Plimpton patented an "improvement in skates" consisting of a stock with four wheels arranged in a two-by-two configuration like a wagon. This was not the first roller skate with two rows of skates. But it was the first double-row skate that could be easily turned by a beginner. Plimpton's key innovation was a mechanism that allowed a skater to turn a skate, by simply leaning towards the desired direction. The mechanism converted rocking and canting motions of the skate platform (stock) into movements of the two wheel axles. These axles in turns steered all four wheel into the right orientations for the turn.

Plimpton opened roller skating rinks, and aggressively promoted this new sport of roller skating. His wheel-steering invention together with his business acumen spread his roller skates far and wide, resulting in a "rinkomania" in the 1860s and 1870s. The editors of 1876 series of "Historical Notes on Roller Skates" (published in the The Engineer) marveled at the number of roller skate patents that resulted from the rinkomania. They compiled a table of roller skate patents issued in Europe and America from 1819 through 1876, showing an exponential growth starting with Plimpton's 1863 invention. Plimpton's skates forever changed the meaning of "roller skates". For the next century, roller skates as a term no longer referred to any wheeled skates. It was now synonymous with the two-by-two Plimpton-style skates.

Adoption of ball bearings

Skates became more practical with the adoption of ball bearings in the wheel assembly. This directly followed the development of precision ball bearings in 1850s, and the applications of ball bearings in bicycles in 1862 by Albert Louis Thirion in England. Ball bearings reduced bearing friction to as little as 10% of former values, greatly improving top speeds of bicycle racers in Europe.

Gidman skate with bearings - 1852

In 1852, Joseph Gidman filed a provisional patent application titled "A skate", where he described a skate with a front wheel, a rear wheel, and two side wheels mounted mid-section. Instead of constructing a wheel with a solid nave, Gidman inserted rollers between a wheel and its axle, effectively applying roller bearings to skate wheels. But Gidman was ahead of his time. He spent 30 years trying to get roller skates with roller bearings mass produced, without much success.

Ball bearings in bikes - Hughes 1877

In 1876, William Bown's provisional patent application was allowed, titled "Improvements in the construction of wheels or rollers for roller skates and for other purposes". Between a wheel and its axle, Bown placed a felt ring lubricated by oil to attempt to reduce friction. But this wasn't substantially more effective, and required constant oil refills.

In 1877, Joseph Henry Hughes' provisional patent application was allowed, titled "Improvements in the bearings of bicycles and velocipedes or carriages". Hughes, a local of Birmingham, described a ball bearing race for bicycle and carriage wheels which allowed for initial adjustment of the system to ensure optimal contacts between components, and for subsequent adjustments to compensate for wear of components from use. As a successful owner of Bown Manufacturing Company, William Bown persuaded Hughes to sell rights to this patent to him, and to join him on further bearing innovations for the next decade. This turned into the successful Aeolus brand of ball bearings, used in the first ball-race-pedals and wheel-bearings for bicycles and carriage wheels. Similar ball bearings were subsequently adopted for use on roller skates.

Ball bearings in skates - Richardson 1884

In 1884, two US patents claiming the use of ball bearings in roller skates were issues one after the other. George Burton filed on August 17, 1883, and was granted a patent on November 11, 1884. Levant Marvin Richardson filed on August 6, 1884, and was granted a patent on December 9, 1884. Richardson more successfully marketed his invention, eventually starting and growing Richardson Ball-Bearing Skate Company to make these skates.

Skates equipped with ball bearings further boosted the Plimpton 2x2 skate craze. Skate makers operated rinks to promote roller skating, in the boom period from 1880s through 1910s. Skates made for rink use were known as parlor skates or club skates. By 1910, Richardson Roller Skate Company competed with mainstream brands including Henley Roller Skates, Winslow's Skates, Baltimore Skate MFG Co, and Chicago Roller Skate Company.

Further development of inline skates

Peck & Snynder - 1873

Skate brake - Edwards 1893

Plimpton's two-by-two roller skates took the limelight, starting in 1863, for more than a century. But inventors and enterprises continued to bring new roller skates with a single-line of wheels to the market, under Plimpton's shadow. For instance, in 1873, Peck & Snyder advertised "parlor or floor skates" with 4 rubber wheels in a single line. These skates had not yet adopted ball bearings. They closely resembled skates advertised in 1861 which were based on Reuben Shaler's 1860 patent.

Early roller skaters were preoccupied with avoiding rolling backward. E. Edwards and H. Koerner patented in 1893 heel brakes that prevented a single-line roller skate from moving backward. This was achieved with the use of a rubber ball to jam with a rear wheel covered with rubber tire. This skate did not claim its straps, ankle support, or overall two-wheel configuration - those preexisted.

Pneumatic road skate - 1895

Racing Roller Skates - 1904

Many single-line roller skates were two-wheeled during this period. In 1895, the Pneumatic Road Skate Company in London took out a full-page advertisement in Figure and Fancy Skating, showing a road skate with two wheels covered in hollowed rubber tires, modeled after bicycle tires. This skate closely resembled the skate shown in the Edwards/Koerner patent. Both provided a similar ankle support popular at that time. These single-line skates were purported to allow easy turning of skates, without needing the rocking/canting mechanism from Plimpton's roller skates. They were advertised as "road" skates with ball bearings, and were hyped as having great military utilities for moving troops. The company performed a public demonstration ahead of its public offering.

Across the Atlantic Ocean in America in 1904, Peck & Snyder Sporting Goods, acquired by A.G. Spalding & Brothers, advertised Racing Roller Skates with two wheels mounted with tempered steel ball bearings and supported by rubber tires. These closely resembled the Pneumatic Road Skates. But the American versions had the ankle support replaced with a strap that today is known as the 45° strap. Many companies produced similar road skates in this period, often called automobile cycle skates, after the pneumatic tires. For instance, John Jay Young was granted patents on steel-tired wheels as early as 1872. But by 1905 he was selling skates with pneumatic wheels. The Cycle Skate and Sporting Goods Company also sold these skates in 1906.

Sherrif/Anderson skate - 1893

Lindsley road skate - 1899

Another popular two-wheeled skate set the foot stand below the centers of wheels. This required that the wheels be placed in front of, and behind the foot stand. In 1893, the first patent describing this configuration was granted to A. Sherrif and R. Anderson. In 1899, Augustus Nichols Lindsley was issued the first patent providing a telescopic stock for this type of skate, to accommodate different foot sizes. It employed T-shaped tubing for the telescopic connections. Benjamin S Peard filed a patent application in 1903, on a type of wheel for roller skates. The wheel used a hub with spokes and fillets to reduce weight while still providing rigidity and strength.

By 1906, Cycle Skate and Sporting Goods Co started to sell road skates that combined features from Sherif/Anderson (low foot stand), Lindsley (adjustable stock), and Peard (wheels with hub and spokes). In 1912, John Jay Young joined the trend and sold similar skates. These were advertised as "Automobile Road Skates" in 1913 and beyond.

Precursors to modern inline skates

Axle as threaded bolt - Harry 1925

From the 1910s to the 1970s, more variations of single-line wheeled skates were patented and/or manufactured. While still shadowed by 2x2 roller skates, some these started to gain popularity amongst ice hockey players, by the 60s and the 70s, due to their improved emulation of ice blades.

In 1925, the US patent office granted Chomin Harry from Canada a patent on a skate frame that gave each wheel axle a dual purpose: 1) interlocking as an axle with the inner race of a double ball bearings, and 2) being threaded into one sidewall of the wheel frame as a bolt. This enabled easy replacement of wheels, and allowed an ice blade to be attached in place of wheels.

Single-piece frame - Siffert 1938

In 1938, Christian Siffert secured a patent on a roller skate frame looking remarkably like 21st century inline skates, complete with a heel brake, even though it had only 3 wheels. This odd selection of wheel numbers was intentional, and led to the patented claim. It allowed the frame to be cut out economically from a single sheet of metal, where the voids seen on frame sidewalls turned into toe and heel plates. This was one of the very few pre-Rollerblade frames where two sidewall of a frame were permanently connected. The resulting single-piece frame was lighter, stronger and cheaper. This skate was produced and sold by Siffert himself initially in 1941, by Best Ever Built Skate Co. (BEB) after that, and still later as "Jet Skate" by AFCO Products Inc. in 1948.

Adjustable frame - Ware 1904

In 1966, Gordon K Ware, one of the Ware bothers that founded the successful Chicago Roller Skate Company, obtained a patent on a skate with multiple frame segments that overlapped. Wheel axles were taxed for a second purpose - that of securing overlapping segments through particular axle holes. This allowed the frame to adjust to different shoes and different shoe sizes. In addition, the front wheel and the rear wheel can be placed higher than the middle two, to create various rockered wheel setups for better turning. Wheels where supported by double ball bearings. This skate could be customized for different needs from different sports, including figure skating, speed skating, and ice hockey.

This Chicago skate was commissioned by Montgomery Ward, and advertised in their 1965 catalogs as great off-ice training tools for figure skating and ice hockey. It was sold under the name "Roller-Blade", coined by Joe Shevelson from the Chicago Roller Skate Co. Ladies' version came with high-cut leather shoes, and mens' version medium-cut leather shoes. Montgomery Ward couldn't sell the inventory, and the skate was soon discontinued.

Up to this time, almost all roller skates were "clamp-on" skates - they were strapped to a skater's own shoes or boots. In his patent application, Ware described his skate as explicitly designed to be permanently riveted to any shoes a user desired to use. This borrowed from the ice hockey industry which by 1908 routinely riveted ice blades to hockey boots, resulting in enhanced stability and performance for skaters.

One-piece hockey skate - Silver 1975

In 1975, Morris (Maury) Silver received a patent on "Tandem roller hockey skate". The key claim of this patent was the one-piece nature of the skate, where a wheel frame was permanently attached to a hockey boot. Prior patents on roller skates did not claim a boot as part of the apparatus. In this patent, the boot was part of the "roller hokey skate". This skate was provisioned with wheels larger than prior art. The front wheel was positioned further in front, and the rear wheel further back, for enhanced speed, maneuverability and balance as required for hockey. And both front and rear wheels can be shifted up in its slotted mounting hole for a rockered wheel setup. The patent and drawings specified the use of roller bearings, when ball bearings were common place by this time.

Silver developed his skate with his friend, the Canadian hockey player Ralph Backstrom from the Montreal Canadiens. Backstrom briefly played for Los Angeles Kings from 1970 to 1973, and would train off-season with this skate. Their company marketed the skate under the label Super Sport Skate (or Super Street Skate), as an off-ice training tool for ice hockey players.

Meanwhile, another roller sport, skateboarding, became popular in the 60s. And avid ocean surfers adopted skateboards with rubber wheels during downtimes. In the 70s, the increasingly popular skateboarding sport was pushed to new heights, with the advent of polyurethane wheels and their superior performance. Some of these polyurethane skateboard wheels were in fact made by the Chicago Roller Skating Co. At the same time in the 1970s, the ski boot manufacturer Lange launched the first molded plastic ski boots furnished with liners. Lange then entered the ice hockey market with similar plastic hard boots, gaining some success. All of these advances will soon be borrowed for modern inline skating, leading to the rise of Rollerblade in the 80s, and its wide adoption by the general population.

Development of modern inline skates

For two centuries, inventors and entrepreneurs attempted to popularize skates with a single row of wheels. By the end of 1970s, only Chicago Roller-Blade and Super Sport Skate managed to gain limited adoptions for training, within a niche community of ice hockey players. It took Scott Olson, his brothers, his friends, and his company, Rollerblade, to perfect these skates, and to make them enjoyable as a mainstream recreation by the general population.

In 1979, Scott Olson, an ice hockey player, stumbled upon the Super Sport Skate (or Super Street Skate). Fascinated by these novelty skates, he soon made a living promoting and selling these to hockey players in Minneapolis. As a licensed distributor, Olson traveled on these skates through the city and around the state, in guerrilla marketing tours to promote the product. Scott Olson and his brother Brennan tinkered with these skates. They removed wheel frames from Super Street Skate, and custom-fit them to customer's own old hockey skates for improved ankle support. Wearing plastic Lange boots thus retrofitted, Scott Olson and his friend Mark Lipson skated for 200 miles from Ninneapolis to Grand Rapids, Minn in one marketing campaign.

Through tinkering, prototyping and road testing everywhere he could, Olson eventually arrived at a design with an adjustable/expandable frame, polyurethane wheels and double bearings. The skate rolled faster, and remained more reliable on road. But a patent search turned up the Chicago Roller-Blade which claimed many of his design features. In 1981, Olson persuaded the Chicago Roller Skate Company to sell him the patent, in exchange for a percent profit. He created a company called Ole's Innovative Sports, and made manufacturing arrangements. Soon he marketed his own "Ultimate Street Skates" (or Ultimate Hockey Skates), a skate of his own design attached to a hard boot with thick liners similar to the Lange boots. He shaved tens of thousands of polyurethane wheels made for roller skates in the progress. These skates came with a toe brake, and had imprinted on them the now-familiar Rollerblade logo which Scott and his friend designed .

In 1982, Olson started to market his skates as a proper sport by itself, venturing out of the initial niche where they served as an off-season training tool for ice hockey. Olson organized Minnesota hockey players to fly East to play roller hockey teams in New York City, with his team skating on Ultimate Street Skates, and the NYC teams on traditional 2x2 skates. Olson also started to advertise his skates to the mass, in print and in person, as everyday fun activities, where one could "roll over large sidewalk craters without feeling them". Enthusiasts colloquially referred to these skates as "roller blades".

In 1983, Olson renamed the company to "North American Sports Training Corporation", and marketed a new generation of skates with heel brakes instead of toe brakes, under the trademark "Rollerblade". His company grew from one worker in 1980, to 25 employees in 1985, selling many thousands of units that year. As the Rollerblade brand became more popular, the company was eventually renamed to Rollerblade as well. In 1988, the company released Lightning skates with fiberglass-reinforced plastic frames. The Lightning TRS (Team Rollerblade series) style was particularly successful, and turned "Rollerblade" into a household name. The company claimed to have up to 75% of the estimated $12 million market, in 1988.

Usage stats of "inline skating" vs rollerblading and roller skating

The Chicago Roller-Blade patent expired at the end of 1983. Eying the success of Rollerblade, competitors jumped into the race. Another Minneapolis firm, First Team Sports Inc. started manufacturing its Ultra Wheels skates in 1986. More manufacturers joined in, including Oxygen, K2, Bauer, etc. Initially, Scott Olson called these skates simply "roller skates", "street skates" or "hockey skates", from 1979 through 1990. But Rollerblade as a company started to relabel roller skating of this style as "in-line", in order to preempt "rollerblading" from becoming a new verb. This was reflected in Brennan Olson's 1987 patent which he titled "In-line roller skate with frame". By 1990, newspapers and the media generally adopted "in-line skating" as the name of this new recreational sport. In 1991, Rollerblade Inc. used "in-line" in the subtitle of its official guidebook Wheel Excitement: "Official Rollerblade® Guide to In-Line Skating". In the same year, "Rollerblade In-Line Skate Association" (RISA) was founded, but quickly changed it name to International Inline Skating Association (IISA) shortly after. When comparing modern inline skates to the 2x2 Plimpton roller skates, enthusiasts referred to the latter as "quad skates". But the term "quad skates" never took hold among the mass.

Rollerblade continued to dominate the market in the 1990s, in the face of competitions. In 1990 it had a 66% of the estimated $50 million global inline market. Sales peaked in 1996, leaving 1997 with a reported revenue of $106 million, or almost 40% of the estimated market. According to Rollerblade, by 1997, 20 percent of American households had a pair of inline skates; and a 1998 survey found that 32 million Americans over the age of six had tried inline skates at least once that year.

Both Scott and Brennan continued to refine skates, each filing a dozen patent applications on skates from 1982 through 1996.

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 boot.

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. Downhill skaters often use boots that are heat-molded to the shape of the foot, with a foam liner.

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 fiber or extruded aluminum (more expensive but more solid), magnesium, or even pressed aluminium, which is then folded into a frame (cheaper but less sturdy).

Carbon fiber frames are expensive but generally more flexible, making for a smoother ride at the expense of worse power transfer between the leg and the wheels. In general, carbon fiber frames weigh about 160–180 grams (5.6–6.3 oz). Recently, high-end carbon fiber frames with a monocoque construction have been introduced. They offer the same level of stiffness as aluminum frames while weighing only around 130 g (4.6 oz). Aluminum can weigh from 170 to 240 grams (6.0 to 8.5 oz). Frame length ranges from two-wheel framed freestyle wheels (used in aggressive skating) to around 230 mm (9.1 in) for short-framed four wheel skates (used in most inline designs), up to about 325 mm (12.8 in) for a five-wheel racing frame.

Bearings

Axles, bearings and spacers

Bearings and spacers in a wheel assembly

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 very important for how long bearings last. 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.

A mistake that is often made in purchasing bearings is that spending more translates to more speed. Generally, clean inline skate bearings contribute about 2% of the rolling resistance that the best urethane inline skate wheels produce, so there is very little opportunity in improving speed by spending more money on bearings. Newer bearings on the market have been offered that use ceramic ball bearings instead of steel, which are more expensive than traditional steel bearings but made of harder material.

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.

Wheels

Inline skate wheels with different diameters and profiles

Wheel sizes vary depending on the skating style.

• 44–72 mm (1.73–2.83 in) for aggressive skating.
• 47–80 mm (1.85–3.15 in) for roller hockey skating.
• 68–72 mm (2.68–2.83 in) for artistic inline skating.
• 72–80 mm (2.83–3.15 in) for freestyle slalom skating and downhill skating.
• 70–90 mm (2.76–3.54 in) for urban skating.
• 72–100 mm (2.83–3.94 in) for general recreational skating.
• 80–90 mm (3.15–3.54 in) for downhill inline skating.
• 100–125 mm (3.94–4.92 in) for tri-skating, mushroom blading, and speed skating.
• 125–150 mm (4.92–5.91 in) tires for off-road skating, and downhill mountain blading with inflatable tires.

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. In general, the bigger the wheel, the faster the skate. A bigger wheel rolls over road imperfections smoothly thus the less bumpy the skating. On top of that, an inline skater trips far less on large wheels. 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 72A-93A (lower numbers are softer, higher numbers are harder). Harder wheels are not necessarily faster but tend to be more durable; soft wheels may have better grip and are generally less affected by road bumps. Harder wheels (which grant minimal elastic hysteresis energy absorption) maintain rolling speed far better while softer wheels (because they grip the surface) accelerate more straightforwardly when striding. In the 1990s, wheel rolling resistance (CRR – coefficient of rolling resistance) tended to be minimized with wheel hardness in the 78A durometer range, with rolling resistance dramatically increasing below 75A durometer and above 85A durometer. In the early 2000s, urethane compounds improved significantly, allowing skaters to use harder compounds to get better wheel life, and get the lowest rolling resistance in the 82A–84A durometer range.

Wheel profiles and thickness again vary by application. Elliptic profiles were thought to minimize friction for a faster ride; however, they were intended to mimic the knife-like properties of an ice blade. They helped define the inner, central and outer edges. Elliptic profiles made the wheel quite maneuverable when turning or otherwise crossing over. More rounded profiles provided lower rolling resistance due to the greater "belly" or tire that increased resilience (or "rebound"); and these wheels were perceived as having better grip and being more stable (less like an ice blade), but were heavier than elliptical-profiled wheels and were often used in downhill racing (such as the Hyper Downhill racing wheels) and in recreational skates. Another advantage of rounded profile wheels is longer wear life due to the increased urethane amount on the tire. To increase stability at high speed, skates intended for downhill skating usually have five or six wheels, in contrast with recreational skates, which typically have four wheels. This advantage of more wheels having less rolling resistance has been largely negated by the 100–110 mm (3.9–4.3 in) diameter wheels with 4-wheel trucks. A flat profile allowed the wheel to be even far stabler than the rounded profile. This profile is almost exclusively used on aggressive skate wheels. On the flip-side, the squared-off shape caused cornering to be tremendously harder, seeing how edges are non-existent with a flat profile. In fact, a flat profile has only a center edge preventing the skater from leaning over.

The core's general design i.e. material, shape, and flexibility/sturdiness degree at the wheel's hub determine the wheel's properties as well. In a classical point of view, wheels on older skate models (during the 1980s and early 1990s) contained no core feature whatsoever. The core is a result of the gradual technological improvement inline skating underwent. Above all else, a wheel lacking a core is prone to deformation. This deformation is a hindrance to the skater's striding ability since in such a case it minimizes the skater's top speed. The core is inserted to hold the polyurethane firmly in place. Despite the setback, markets still distribute special wheels without a core. Core designs vary among open, full or semi-open. 'Spokes' are an element seen in wheels whose cores are open which generally increase overall wheel lightness. These are inserted into the hubs of wheels for inline speed skates, fitness skates, recreational skates, some slalom skates and artistic/figure inline skates. Apart from spokes, other open-cores can be hollowed out internally. The main disadvantage about an open core is that their design does not permit sturdiness hence they are highly likely to snap under too much pressure i.e. when jumping. Another trade-off with open cores is the lesser amount of polyurethane around it to compensate for the spoked or hollow shape meaning they last shorter. Full cores are entirely solid, akin to a pipe's cross-section. This core design is mostly favored amongst aggressive skaters whose leaps off higher levels strain the wheels when landing. Of course, these cores (alongside the extra polyurethane) tend to add weight on the wheel. Some even disfavor the full core design for its rigidity that feels uncomfortable. The question still stands on whether a full core improves power transfer. Semi-open cores are a hybrid between the two previously mentioned cores seen on wheels for urban skates, slalom skates and inline hockey skates. Minuscule holes are typically punctured into these solid cores to provide a semi-open design.

Heel brakes or toe stops

Heel brake

A hard rubber brake attached to the heel of the frame allows the skater to stop by lifting the toes of the skate, forcing the brake onto the ground. Learning how to use the heel brake is very important for beginners, as it is the easiest way to stop in emergencies and to control speed on downhills. Also, with practice, beginners realise if the heel brakes are better placed for them on the left/right foot.

Heel brakes can interfere with a useful technique called a crossover turn, in which a skater crosses one leg over another to make a sharp turn without losing much speed; for this reason, most intermediate to advanced users prefer not to use heel brakes. Skaters in the freestyle slalom and aggressive inline skating disciplines do not use heel brakes, since they limit the skater's ability to perform tricks effectively. Aggressive inline skates and racing skates generally have no heel brake, thereby permitting extra speed and control.

Inline skaters lacking a 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 reduce speed, or the more advanced maneuver of a hockey stop/snow plow stop, in which the skater quickly moves both skates perpendicular to the path of motion.

For artistic roller skating purposes, inline figure skates can also feature a "toe stop" which aids in performing figure skating jumps.

Setups

Flat setup

A flat setup is the most common setup used on inline skates. Almost all non-aggressive inline skates are sold with a flat wheel setup. Flat means that all the wheels touch the ground at the same time when resting on flat ground. Flat setups are not the most maneuverable but what they lack in maneuverability they make up for in speed. Flat setups tend to be the fastest setups, compared to setups such as the Hi-Lo or anti-rocker. The presence of two middle wheels matching the diametrical size of the rest increases contact points with any surface. They also minimize the rate at which the skater's loading weight deforms the wheels. This minimizes the wheel's footprint thereby minimizing rolling resistance. Speed skaters and marathon skaters normally use flat setups. This setup also allows for a powerslide, an advanced braking method.

Aggressive skates are sometimes sold with flat setups, but with a small space in the middle for grinding. With aggressive skates, the flat setup obviously leads to better control on the ground when either accelerating on a push or decelerating on a drag because of increased traction. It also grants a faster speed, translating to faster grinds, more powerful pumps in a skate ramp and/or higher heights ('airs') off the edge of a vert ramp. Indeed, flat setups are quick save for the likelihood that they will be heavier and the two standard central wheels tend to 'bite' when grinding. Similar to skateboarding in certain respects, 'biting' is a common hindrance during grinding whereby friction between the wheel(s) and surface it comes into contact causes the wheel(s) then entire boot to suddenly reach a halt and the momentum throws the aggressive inline skater off the rail or ledge. Again, the aspect of wheel profile is key here. A harder wheel on a flat setup will slide and 'bite' less than a softer wheel. Likewise an elliptical profile (Undercover's Dustin Werbeski 'super bullet' wheels for example) possesses less surface area hence it will not bite as much either. Adjusting to a flat setup can even out shock when landing jumps. In doing so, an inline skater's hardware like wheels, bearings, axles and the frame itself are twice as much to be spared damage.

A 'flat' inline setup

It is worth noting that having a flat setup is just one factor in a fast skate setup. A long frame, low resistance bearings, and good technique all contribute greatly to a skater's speed.

Full 'crescent/banana' rocker

Full rockers are used by skaters who favor maneuverability when skating on flat ground. Freestyle skaters, freestyle slalom skaters and artistic inline skaters tend to use this setup. Inline hockey players no less can customize their wheels to implement this setup (especially those who favor nimble change in direction over sheer speed during a match). This setup is called "crescent" or "banana" because it is curved, and mimics a curved ice blade profile. On flat ground this setup will only have 1–2 wheels touching the ground at any one time. This makes the skate much easier to pivot but lacks stability so it is harder to balance on. To attain balance when learning to skate a full rocker, it is recommended that pressure and weight are deposited on either the two middle wheels or the two wheels in the back. Avoid applying pressure on the two front wheels when taking strides since this is what will cause instability. In addition, a full rocker is slower than a flat setup in terms of top speed. Worst of all at high speeds, skates with a full rocker setup can experience a speed wobble, where they oscillate uncontrollably. The skater may lose control and crash to the ground.

A full 'crescent/banana' rocker inline setup

Flat setups generally wear into a 'natural' rocker. This is because the front and back wheels seem to receive the vast majority of wear on inline skates.

Having a short frame (230–245 mm [9.1–9.6 in]) in combination with a full rocker is optimum for achieving the highest maneuverability when skating.

Front rocker

Front rockers are often used by street skaters who want to combine the ability of a full rocker to handle imperfections in the ground with a flat setup's sheer speed. Having a smaller wheel at the front encourages the front wheel to guide the rest of the skate over ground imperfections, rather than digging in and tripping up the less experienced skater. Maintaining a flat profile at the back allows the skater to transfer power through the rear of the skate efficiently to maintain a good speed.

A front rocker inline setup

‘Hi-Lo’ setup

Some hockey skates inline speed skates include a Hi-Lo setup. Hi-Lo setups resemble a flat setup in that all 4 wheels touch the ground at the same time. Unlike a flat setup, however, different wheel sizes are used. The front two wheels will be smaller than the back two wheels. This is possible because of the location of the axles on the frame itself. One example is a Bauer frame that has two wheels in the front that are 76 mm (3.0 in) and two wheels in the back that are 80 mm (3.1 in). Another example is a 74–76–78–80 mm (2.9–3.0–3.1–3.1 in) wheel arrangement. This drastically changed the pace at which inline hockey players accelerated. Furthermore, by transferring weight forward, the skater could sprint explosively off the toe section and reduce instances of falling backwards. If the hockey skate is used recreationally outside the arena, the skater will find climbing slopes much easier than on a flat setup. As inline hockey skate manufacturers design frames with varying axle hole placements or even raise the frame's back bolt to be higher than the front bolt nowadays, wheels of the same diameter (like 80 mm [3.1 in]) can be used entirely.

Beyond inline hockey, the Hi-Lo setup was an experimental component seen on K2's VO2 100 X Pro where the manufacturers believed that the two smaller wheels (90 mm [3.5 in] each) in front would increase stability and rate of acceleration while the two bigger wheels (100 mm [3.9 in] each) in the back would maintain high speeds. Essentially this K2 skate model married both wheel size properties. A Hi-Lo configuration on an inline speed skate employs three large sized wheels and a smaller sized wheel between the first and third wheels beneath the ball part of the foot (see speed skates). An example is a 110–100–110–110 mm (4.3–3.9–4.3–4.3 in) arrangement beginning front to back. This increases efficiency now that the foot pushes on a smaller wheel. The smaller wheel lowers deck height off the ground improving stability and keeps the frame length shorter improving maneuverability and comfort amongst speed skaters having a smaller foot size. This is desirable seeing how wheels on inline speed skates are enormous enough to occupy a lot of room in frames. Unfortunately, top speed for a Hi-Lo setup is far less than that for a flat setup where same sized large wheels are used.

'TriDi' Hi-Lo setup

Another variant of the setup in which there are three diameters of wheels. It is supposed to emphasize the same benefits as the HiLo system but with greater maneuverability due to the smaller front wheels. The configuration is 72 mm (2.83 in), 76 mm (2.99 in), 80 mm (3.15 in), 76 mm (2.99 in). It allows one to pivot on the third wheel similar to the brand Wizard Skates. This system is also used by some hockey skaters as it pitches the foot slightly forward.

Aggressive Hi-Lo setup

A few aggressive skate frames (most notably Rollerblade's Switch Frame, Ground Control's Bullet Frame, Oysi Frame and Joe Atkinson Sola Frame) are designed so that there are two big outer wheels, and two small inner wheels, rockered so that they all touch the ground. This gives the benefits of a flat setup, while keeping the frame as low as the height of the smaller inner wheels. It also retains room for an H-block in the center. But out bigger outer wheels give some of the benefits bigger wheels offer such as speed and stability.

Anti-rocker

Anti-rocker is the most popular setup for aggressive skaters. An anti-rocker wheel is a small hard wheel that replaces the two middle wheels. Anti-rocker wheels almost never touch the ground except in cases where the terrain is uneven, such as skating over a ramp. Anti-rockers can be made of plastic, or high density polyurethane. Some use bearings so that they can spin. As they can spin, the anti-rockers wear out more evenly when grinding. Anti-rockers containing bearings can effectively roll over uneven ground or features like steps, lessening tripping hazards. Others do not use bearings so that they're lighter. The anti-rockers themselves lock the H-block onto the ledge or rail a skater grinds. There is a minor nuisance to anti-rocker hardware in which the items emit a loud noise upon fastening into a grind that some aggressive skaters find unbearable. The anti-rocker setup altogether makes maneuvering harder (since the standard wheels slip more), wheel life shorter, overall speed slower, a rougher ride, and a wider turning radius, but because of the extra space in the middle, it makes grinding objects much easier than with a flat setup.

Freestyle

The freestyle frame is another setup used by aggressive skaters. This setup simply has only two wheels – one in the front and one in the back. In between the two wheels is an area of solid material, resembling a large "H Block", which is used for grinding. Freestyle frames have nearly identical advantages to the Anti-rocker. Since large space is freed up in the middle, the skater can not only grind wider surface areas like an entire ledge but also the frame's weight is lighter. Likewise, the Freestyle frame shares its disadvantages with its Anti-rocker cousin already listed. As opposed to anti-rockers which securely lock grinds, aggressive skaters should train themselves to remain balanced when sliding across narrow rails or edges on a Freestyle frame. Worse still when not observing carefulness, a Freestyle setup can easily hook on vertical surfaces including steps, coping and funbox edges if you roll over them, leading to tripping incidents. This is why the technique to 'bash' (see Flat Setup) a staircase is almost impossible on a Freestyle setup. Freestyle frames can be purchased, although removing the two inner wheels of a flat or anti-rocker frame technically makes it freestyle, however this would not be very durable due to the lack of solid grinding material. Originally invented by Fifty-50 (an aggressive inline skate frame company), Juice Blocks allow the skater to convert their flat or anti-rocker frames into proper freestyle frames. Juice Blocks are simply solid grind blocks inserted into the axle holes where two middle wheels or anti-rockers are found.

Tri-rocker

Tri-rocker (not to be confused with the 3-wheeled frame/chassis seen on Tri-Skates) is used by some aggressive skaters. It is another method of making grinds easier. A frame with a tri-rocker setup has only one wheel in the middle, either in the second wheel position or in the third wheel position, depending on what kinds of grinds the skater plans on doing. The remaining axle has an anti-rocker wheel, a special grind block, or is just left empty.

The purpose of a tri-rocker setup is to give the skater good speed and maneuverability, like on a flat setup. But because of the extra space, grinding is also a little easier than a flat setup.

Gallery

• 
  Typical inline skate
• 
  Typical inline skate
• 
  Fila brand inline skates
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  Skating protection gear
• 
  Inline skate wheels
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  Child's Inline Skates
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  Aggressive inline skates
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  Typical In-line skating protective gear includes helmet, elbow pads, wrist guards, and knee pads.
• 
  An inline skate designed for artistic roller skating

See also

Forms of inline skating:

• Aggressive inline skating
• Artistic roller skating
• Freestyle slalom skating
• Ice skates
• Inline figure skating
• Inline hockey
• Inline speed skating
• Roller shoe
• Road skating
• Roller skates
• Vert skating

External links

• The National Museum of Roller Skating
• Skating Book FAQ / Bibliography, part 1 of 2 - includes a large listing of inline skating books published in the heyday of inline skating, in the 1990s.