Inline skates areboots withwheels arranged in a single line from front to back, allowing one to move in anice skate-like fashion. Inline skates are technically a type ofroller skate, but most people associate the term roller skates with quad skates, another type of roller skate with a two-by-two wheel arrangement similar to a car. Quad skates were popularized in the late 19th and early 20th centuries. Inline skates became prominent in the late 1980s with the rise ofRollerblade, Inc., and peaked in the late 1990s. The registeredtrademarkRollerblade has since become ageneric trademark: "rollerblading" is now a verb for skating with inline skates, or "rollerblades."
In the 21st century, inline skates come in many varieties, suitable for different types ofinline skating activities and sports such as recreational skating,urban skating,roller hockey,street hockey,speed skating,slalom skating,aggressive skating,vert skating, andartistic inline skating. Inlineskaters can be found at traditionalroller 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.[1][2] Wednesday Night Skate NYC is its equivalent in New York City, also run by volunteers, albeit smaller in size.[3][4]
The documented history of inline skates dates back to the early 18th century, when enterprising inventors sought to make boots roll on wheels to emulate the gliding of ice blades on dry land. Because these wheeled skates were modeled after ice blades, their wheels were arranged in a single line. Skates were simply assumed to have a single runner, whether it was a steel blade on anice skate or a row of wheels on a wheeled skate.[5]
The firstpatented wheeled skate was filed in France in 1819 by Charles-Louis Petibled.[6] From that point forward, more patents and documented designs continued to explore wheeled alternatives to ice skates.[7] Around 1860, wheeled skates began to gain popularity, and new patents appeared under names such as "roller-skates" and "parlor skates". As inventions increased, roller skates began to diverge from the original single-line layout.[8] Inventors experimented with two rows of wheels as a learning platform for beginner skaters.[9] These double-row skates offered greater stability, but they were difficult to turn.[10]
In 1863,James Plimpton invented a roller skate with four wheels arranged in a two-by-two configuration, similar to awagon, and added a clever mechanism for turning.[11] It was the first double-row skate that allowed beginners tosteer easily by simply leaning in the desired direction.[12] Plimpton's invention sparked a rapid rise in roller skate popularity and spread across both sides of theAtlantic, creating a period of "rinkomania" during the 1860s and 1870s.[13] His design also redefined the term "roller skate", which no longer referred to all wheeled skates but became synonymous with the "two-by-two" Plimpton style.[A]
The development of precisionball bearings in the mid-19th century helped makebicycles more efficient and practical.[15] By the 1880s, Plimpton-style roller skates similarly incorporated ball bearings into their wheel assemblies, making skates roll more efficiently.[16] At the same time, manufacturers began operatingskating rinks as promotional ventures from the 1880s through the 1910s. All of these further fueled the Plimpton skate craze.[7]: 19–20, 25
Although Plimpton's roller skates took center stage, inventors and enterprises continued to introduce new roller skates with a single line of wheels between the 1870s and the 1910s.[17] These models included features such asbrakes,pneumatic tires, andfoot stands placed below the center of the wheels.[B]
From the 1910s through the 1970s, many new variations of single-line wheeled skates were patented and manufactured.[18] While still in the shadow of 2x2 roller skates, some models began to gain popularity amongice hockey players by the 1960s and 1970s, due to their better emulation of ice blades. In particular, off-season training skates used byUSSRspeed skaters inspired Gordon Ware of the Chicago Roller Skate Company to develop and patent a wheeled skate,[19] which was sold throughMontgomery Ward in 1965 under the name "Roller-Blade".[20][C] In 1973,Ralph Backstrom promoted the Super Sport Skate,[21] a joint venture with his friend Maury Silver, as an off-season training tool for hockey players.[22][D] Both of these skate models became direct precursors to modern inline skates.[E]
In a related development, theski boot manufacturerLange introduced the firstmolded plastic ski boots with internal liners in the 1960s.[24] In the 1970s, Lange entered the ice hockey market with similarplastic boots featuring hinged cuffs and achieved some success.[25] Meanwhile,skateboarding reached new heights during the 1970s, thanks to the introduction ofpolyurethane wheels and their superior performance.[26] The confluence of molded plastic boots with hinged cuffs, polyurethane wheels, Super Sport Skates, and the earlier Chicago Roller-Blade laid the foundation for the emergence of Rollerblade in the 1980s and its widespread appeal among the general public.[27]: 12–16 [20]
In 1979, Scott Olson, a hockey player fromMinneapolis, discovered the Super Sport Skate. He began selling them to local hockey players as a licenseddistributor and soon started modifying them.[28] Olson, his brother Brennan, his family, and his friends replaced the stock boots with customers' old hockey boots and swapped out the original wheels for polyurethane ones.[29][30] Through further tinkering, prototyping and road testing everywhere he could, Olson eventually arrived at a skate design with a plastic ski boot, an adjustable/expandable frame, polyurethane wheels and double ball bearings.[31][32][F][G] This skate rolled faster, and remained more reliable on road surfaces. However, a patent search revealed that the Chicago Roller-Blade already covered many of these features. In 1981, Olson persuaded the Chicago Roller Skate Company to transfer the patent to him in exchange for a share of future profits.[34]
Thus began the modern history of inline skates, with Olson's company eventually becoming known asRollerblade, Inc. by around 1988.[35] The registeredtrademark "Rollerblade" became so well known that it entered common usage as ageneric trademark.[36][37] Around this time, the company began promoting the term "in-line skating" in an effort to prevent "rollerblading" from becoming a verb.[30][38] The campaign proved effective, as media outlets, newspapers, and competitors adopted "in-line skating" as the preferred term by 1990.[39] The phrase was soon shortened to "inline", the name by which these skates are known today.[H]
Modern inline skates became practical formass production and appealing as arecreational activity once key technologies came together. These included polyurethane wheels,ISO 608 standard ball bearings, and molded plastic boots. These skates incorporate double ball bearings withdual-purpose axles from Chomin Harry (1925),[40]single-piece frames from Christian Siffert (1938),[41]adjustable wheel rockering from Gordon Ware (1966),[19]single-unit boot/hockey frame with larger wheels from Maury Silver (1975),[21] plus additional innovations.[I]
All modern inline skates share a common basic blueprint. A skate comprises aboot, worn on the foot. To the bottom of the boot is attached aframe, the most rigid part of the skate. The frame holds a number ofwheels in place with wheelaxles. In between a wheel and an axle are twobearings. Bearings allow a wheel to rotate freely around its axle. Finally, a rubberbrake typically attaches to the frame of the right boot, onrecreational skates.[27]: 17–27 [42]: 14–39 [43]: 41–51
For many skaters, the frame is never removed or replaced. But wheels are consumables, as they wear down with use, and require periodic mounting rotations and even replacements.[36]: 81–86 Inline skates usually come with a skate tool for wheel, bearing and frame maintenance. The tool will have ahex wrench or aTorx wrench for removing wheel axles from a frame, and wherever applicable, for removing bearings from a wheel, and for removing a frame from a boot.[44][27]: 39–45 [42]: 39–51
In the 1980s and 1990s, all inline skates hadhard boots, borrowed from ski boot designs. A removable liner in a hard boot provides a snug yet comfortable fit between a skater's foot and the hard shell. Around 1996,K2 introducedsoft boots with an exoskeleton. These provide the most comfortable fit, at the expense of reduced rigidity. In the 2010s,hybrid (soft) boots with an endoskeleton were introduced to the high-end market. A hybrid boot has an integrated, non-removable liner. This is glued to a rigid endoskeleton shell integrated with the sole, providing direct power transfer from the foot to the wheels.[45]: 142 [46][47]
All three types are able to secure a foot in them without slack, with proper closure systems. Soft boots are oftenlaced, and hard shells are usually secured withbuckles.Velcrostraps are also common in all types of boots. Well-designed boots provide properheel support andankle support to a skater.[42]: 14–39 [43]: 47–52 [45]: 142
Choosing the right skates involves weighing various trade-offs. Thelength of a frame positively affects stability and negatively affects turning agility. Longer frames accommodate more wheels, and taller frames larger wheels; both positively affect top skating speed. Modern inline skates are equipped withpolyurethane wheels. Softer wheels provide a better grip on smooth indoor surfaces, while harder wheels wear down less on rough outdoor surfaces. Beginners skate with all wheels touching the ground, for enhanced stability, known as aflat wheel setup. Advanced skaters may choose to configure wheels in arockered setup for enhanced maneuverability. The weight of a skate is an important consideration for some disciplines. Lighter boots, frames, and wheels are preferred. However, weight reduction is only achieved with escalating costs anddiminishing returns.[42]: 14–39 [48]: 19–33
Recreational inline skating involves a continuous interplay between striding and gliding. As one foot pushes laterally against the ground during the striding phase, it converts sideways force into forward momentum. Meanwhile, the opposite foot glides ahead, supporting the skater's weight. These phases overlap fluidly, with each skate alternating between pushing and gliding in a coordinated rhythm that sustains forward motion.[49][43]: 57–75 [50]: 9–17
These two movements place distinct and often conflicting demands on skate design. A powerful stride benefits from a large contact area between the wheels and the ground, maximizingstatic friction for a more forceful push-off. In contrast, a smooth and sustained glide calls for minimal contact to minimizerolling friction. Much of inline skate design involves balancing these opposing requirements to achieve bothpropulsion andefficiency.[51][52]
Modern inline skate design was heavily influenced by ice hockey. Early inline skates from the 1980s aimed to replicate the feel of hockey skate blades, often using arockered wheel setup to allow easier turning and quick directional changes. Whileslalom skaters relied on these rockered setups and hockey players made rapid turns usingcrossover maneuvers, recreational skaters soon realized that even aflat wheel setup could support effective turning, thanks to the grip provided by polyurethane wheels on pavement. As withice skating, inline skaters could shift their body weight and apply pressure to one side of the skate to gradually turn while gliding.[36]: 81–86 [49][51][52]
This technique is known as "edging", which involves tilting the skate to roll on one side of the wheels. Skaters use both sides of the wheels for different maneuvers. The inside edge refers to the side of the wheel facing the skater's body, while the outside edge faces away.[J] Edging is essential not only for turning but also for powerful stride pushes, which require a strong edge angle. Deep edging, however, requires proper support from the boot, frame, and wheels to prevent the foot from wobbling within the boot and to keep the wheels from sliding out from under the skater.[42]: 19–20, 37–38 [48]: 19–24 [43]: 47–52
Heel support refers to the ability of a boot to keep a skater'sheel comfortably seated and firmly locked down in the heel pocket of the boot, even during aggressive maneuvering.[42]: 15–18
A "heel pocket" is formed by the shell, inner liner andsole of aboot. A properly designed boot has a heel pocket that hugs the heel, with ananatomical contour. A properclosure system causes the "facing" (where eyelet tabs are) to push theinstep against the heel pocket, preventing the foot from shifting or lifting during maneuvers. As a result, the heel remains in contact with the footbed at all times.[42]: 15–18 [53]
Proper heel lock serves as a stable foundation for the entire foot. It allows a skater to adopt an athletic stance for skating byflexing thelower leg forward, without lifting the heel from the insole. A snug fit means reduced movement of the foot within the skate, and thus reduced opportunity for friction to causeblisters. At the same time, the whole skate becomes transfixed to the foot as an extension of it, allowing efficient strides with a faithful transfer of power from the foot to the ground.[54]: 35–36, 79–80 [42]: 15–17
Ankle support refers to the ability of a boot to prevent sideways movement of a skater'sankle and lower leg, while allowing theshin to flex forward into an athletic stance. In some skates, such asrecreational andaggressive skates, this is achieved via a hinged cuff. In other skates, such ashockey skates, this is enabled by rigid, and anatomically shapedquarter panels that lock theankle in place, from two sides, leaving the shin to freely pivot forward.[42]: 5, 15–18 [55][45]: 142 [56] One primary concern of ankle support involves accommodating the two bonymalleolus protrusions on either side of the ankle, colloquially known as ankle bones.[K]
Proper ankle support allows a novice skater to keep a skate upright as a straight extension of their entire leg, when observed from the front. Without rigid support on both sides of the ankle, the foot may wobble within the boot, causing the skate to tilt inward or outward. This typically createspronation in beginners based on naturalbipedal gait, making it harder for a skater to glide on a single skate at best, and resulting in sprains and other injuries at worst.[58]
A properly designed boot allows a skater to pivot the lower leg (the shin) forward about theankle joint to adopt asquatting (athletic) stance, despite the sidewayankle support.[58] This forward flex (or forward leaning) is known asdorsiflexion of the foot.[42]: 15–17 It places thecenter of body mass atop theball of the foot, a balancing skill crucial to most skating moves.[54]: 34–36 This deep squatting posture also produces powerfulpush-offs, with the farthest displacement of the striding skate.[50]: 5–11
Without such a squatting stance, the leg and the skate form a 90° angle, placing the entire body weight of a skater on the rear wheel of the skate. This is dangerous for a beginner because a small backward shift of the upper body will cause a skater to pivot their entire body on the rear wheel, and thus fall uncontrollably backward.[42]: 67–77 [43]: 57–59 [49]
Some inline skates feature a boot design where theheel is positioned substantially higher than thetoe. This forward tilt encourages the skater to lean slightly forward by default, simulating a mildforward flex. The design is commonly referred to as "heel raise" or a "raised heel".[59][60] The height difference between the heel and toe is known in thefootwear industry as the "heel-to-toe drop" or simply the "pitch".[61][62] Pitch can result from a combination offrame mounting design, as seen in the165mm andTrinity standards,[63] and from using wheels of different sizes, as inhockey skates that employ ahi-lo setup.[64]
Heel raise is sometimes called "heel lift".[65][66] However, the term "heel lift" also colloquially describes a completely different condition: heel slippage - the lack ofheel lock. In this case, the heel lifts off the insole when the skater flexes the shin forward, which can lead to inefficiencies and blisters.[67]
There are a variety of ways to design and make modern inline skates. Different types of inline skates reflect needs specific to differentinline skating disciplines, such as recreational skating,urban skating,roller hockey,street hockey,speed skating,slalom skating,aggressive skating, andartistic inline skating.
Manufacturers andresellers generally classify inline skates based on disciplines, such as aggressive skates, speed skates and hockey skates.[42]: 30–38 Some disciplines are not large enough to warrant their own classification. Thus, dissimilar disciplines with similar equipment needs are grouped under a single skate category. For instance, freestyle skating, slalom skating, wizard skating, city commuting, and urban skating may be crammed into a single "urban skates" category.[68] Then, there are the rest of skaters who casually skate, skate forfitness, or skate forcross-training. These purposes constitute 90% of actual inline skatesales. Skates suitable for these activities are often grouped together as "recreational skates".[46]
Some makers refer to recreational skates as "fitness skates". Others split them into two or more categories:recreational,fitness, andcross-training. Usually, the fitness and cross-training categories reflect increasing cost and thus quality of skates.[L]Soft boots with an exoskeleton are usually the least expensive.Hard boots with removable liners are often priced higher.Hybrid boots with an endoskeleton are high-end models.[55][47]
This category can be better understood as "unspecialized" inline skates, or generic skates. All other types of skates can be thought of as specialized deviations from this basic type.[46] Recreational skates usually come with four wheels of average size, and a frame of average length, which is just slightly longer than the boot. This places the front wheel halfway ahead of the toe box, and the rear wheel halfway behind the heel pocket, a design that remained unchanged since Scott Olson's adoption ofSuper Sport Skate from 1979.[21] Recreational skates are equipped withheel brakes. These allow beginners to learn to stop rolling, with a simple pivot of a foot on its heel.[27]: 25–26, 44–45, 52–57
Aggressive skates are the most specialized inline skates, in contrast to recreational skates. They are designed for one specific purpose only:grinds. Grinding is the art of sliding on street obstacles such asstairs,rails,benches,curbs,ramps andwalls.[45]: 134–163 To support these stunts, aggressive skates are generally built with stronghard boots based onplastic ski boots and bolted to thickframes which are fitted with the smallest wheels in all of inline skating.[69] To help a skater lock onto an obstacle of interest during a grind, an aggressive skate provides channels and surfaces such as H-blocks, frame grooves, backslide grooves, grind plates,soulplates, etc.[70] Transitioning between these stunts, a skater often jumps considerable heights, or rides down a long flight of stairs (known as stair bashing).[42]: 33, 156–168 Thus, aggressive boots are often fitted with shock absorbers todampen shocks upon landing.[70]
Rollerblade Lightning TRS has been widely credited for enablingaggressive inline skating as a sport, with its durable boot and its nylon-reinforced frame.[60] Aggressive skates co-evolved with the discipline which started as "inline stunts".[54]: 98–110 It then turned into "streetstyle skating", and finally into "aggressive inline skating". The word "street" in "street-style" meant that skaters performed tricks on and over "street obstacles", following nomenclature fromskateboarding.[27]: 6, 64–77, 170–174 Skaters grind on street obstacles (termed "street skating"), perform stunts atskateparks (termed "park skating"), and take to the air at the top ofvert ramps (termed "vert skating").[42]: 33, 156–168
Aggressive skates havestandardized on UFS, the Universal Frame System. Most UFS frames accommodate small wheels up to60 mm.[71] Some UFS frames with frame grooves and H-blocks are designed with thick walls to prevent wheel bites. allowing them to be used with aflat wheel setup.[70] Other UFS frames without prevention measures against wheel bites can be set up with ananti-rocker wheel setup, with even smaller and harder grindwheels (or antirockers) in the middle.[72] Some skaters go one step further, replacing the two middle wheels with non-rotating "juice blocks".[73]
The name "aggressive" has been controversial.[74] Many in the community call aggressive skating "rollerblading" (or simply "blading"), and thus members "bladers".[46] Others call it "aggro".[45]: 134–163 [M] Some skate manufacturers eschew the label "aggressive", choosing to market their aggressive skates instead as "street skates" or "park skates".[75]: 40–41 [N]
In the 21st century, the boots used for inline hockey skates (or roller hockey skates) are constructed using a process that differs significantly from those of other inline skates.[76] They are primarily produced byice hockey manufacturers such asCCM,Bauer (Mission),True, and Marsblade.[42]: 37–38 [O] In many cases, the same boot is used across both sports, with either a blade holder for ice hockey, or an inline frame forroller hockey.[P][Q] As a result, inline hockey skates continue to rely on therivet-based mounting system used in ice hockey, even though replaceable frame standards have become common in other skate categories.[71]
Hockey skates feature some of theshortest frames among all inline skates, enabling players to make tight turns and perform crossovers without interference. Hockey boots are designed to sit as low to the ground as possible, limiting them to smaller wheels. This configuration maximizes stability forhard edging maneuvers. Wheels with arounder profile are preferred, as they offer improvedgrip and control during sharp turns at all edging angles.[48]: 19–24 [42]: 37–38 Many hockey skates use ahi-lo wheel setup, with larger wheels in the rear and smaller ones in the front. This raises the heel and lowers the toe cap, thus the name "hi-lo". It causes a player toforward flex naturally, for greater stability and strongerstrokes.[79]
Themodern inline skate was originally created as a training substitute for ice hockey skates, featuring a boot with ahard shell, pivoting cuff, and removable liner.[36] This style of boot construction remains popular across all inline disciplines, ironically with the exception of inline hockey. Instead, hockey boots have followed their own path.[80][R] They are built to be as lightweight as economically feasible while still delivering excellentheel andankle support, along with protection against impacts from flying pucks. Direct and immediatepower transfer from foot to wheel is also essential. To achieve this, hockey boots are constructed around an unyielding wall withanatomical contours to hug the heel and both sides of the ankle. This structure is called the "quarter package", made of left and right quarter panels bolted to a rigidoutsole platform.[78][76] The rest of the boot is built around this base, including a thicktongue that supports the shin in a forward-leaning athletic stance, and a reinforcedtoe cap. The liner is integrated into the boot and not removable, with strategically varied thickness for best anatomical fit. Hockey skates are secured with eyelets andlaces, rather thanbuckles orstraps.[57][77]
Speed skates (or race skates) are purpose-built inline skates with a single goal: speed. They enable aracer tostride with maximal efficiency and toglide with the least amount of friction.[50]: 3–9, 283–318 Joey Mantia holds theworld record for the outdoor 10-kilometers at over 27 miles per hour.[81]
Speed skating differs from other inline disciplines in that a speed skater tilts herbody trunk forward for up to 60° when racing, to reduceair resistance. A speed skater bends her knees aggressively for up to 80° in a deep-seatedsquatting position which requires a deepforward leaning of the shin (dorsiflexion) for proper balance. This deep squatting posture produces the most powerful push-offs, with the farthest displacement of the pushing skate.[50]: 5–11
Because of the need for a deep dorsiflexion, speed skates have no eyelets, buckles, or straps above middle eyelets at 45° angle. In order for racers to freely flex their foot aroundankle bones,[K] speed boots are cut the lowest among all inline skates, around or below the ankle bones. The removal of shaft and cuff significantly reduces a boot's weight.[42]: 17, 34–36 [50]: 3–30, 308–311 Most speed boots are custom-fitted without much padding, or elseheat-moldable, to prevent the foot from the slightest wobbling.[82][S]
Theframe may be made of aircraft-qualityaluminum,magnesium, or possibly lightweightcarbon fiber, such that it flexes very little and transmits power from the foot to the wheels more directly. The length and height of a frame determine the number and size of wheels it can accommodate. More wheels and bigger wheels increasemass, makingacceleration harder and slower. But once rolling at speed, a skater can more easily maintain top speed given therotational inertia. In the 21st century, wheel size ranges from90 mm to125 mm. Asetup with four110 mm wheels (4x110mm) is typical for competitive speed skating, and three125 mm wheels (3x125mm) formarathon skates at marathon events.[42]: 18–24, 34–36 [84] Speed skates generally adopt either the165mm or the195mm mounting standard. Both of these 2-point mounting standards feature a built-inheel raise that pitches a skater forward, creating forward flex.[63]
Speed skating generally adoptsharder andhigh-rebound wheels to minimize energy lost toelastic hysteresis. Speed wheels have a pointybullet profile that reduces friction from drags when gliding upright, while still providing a large contact surface for improved traction and control when pushing off at adeep edging angle.[50]: 315–316 Speed skaters use High-qualitybearings with precision ratings, and perform regular cleaning and lubrication to removetrapped dirt and restore them to their optimal performance.[27]: 128–130
Urban skate is an umbrella term for a type of skate suitable for several niche inline disciplines: freestyle skating, slalom skating, wizard skating, city commuting, andurban skating. These activities take place on relatively flat ground, but the surface may not always be paved or smooth.[68]
Freestyle skating is named after its counterpart inskateboarding, just likeaggressive street, park, and vert skating are named after street, park, and vert skateboarding, respectively. Freestyle skating is the art of performing skating tricks on relatively flat ground, free of obstacles.[85]Freestyle slalom skating is a form of freestyle skating where tricks are performed around slalom cones. This is standardized by the International Freestyle Skaters Association (IFSA) andWorld Skate as "freestyle slalom" to distinguish it from "speed slalom", which is a form of speed skating around cones on flat ground.[86][87] Freestyle skating requires skates that support rigorousturning and edging maneuvers, with characteristics similar tohockey skates. Arockered setup with76-80 mm wheels on a relativelyshort frame is common for freestyle skating.[88]: 15–25 [69]
Urban skating, also known as "city commuting", takes the activity to thestreet. But the term "street skating" is already taken as a subdiscipline ofaggressive skating, for grinding on street obstacles. Thus, this niche market is variously promoted as skating onpaved roads orcommuting to work on skates. These activities demandlonger frames andlarger wheels for higher cruising speed, stable tracking, and more comfortable rides on uneven surfaces, similar tospeed skates for marathon events. Commonwheel setups include 4x80mm, 4x90mm, 4x100mm, 3x100mm, 3x110mm, and 3x125mm.[68][69] Most urban skate boots support either the165mm orTrinity mounting standard, and can be customized with a short frame and average-sized wheels for slalom skating, or with a long frame and large wheels for long-distance road skating.[71][89] Both the 165mm and Trinity mounting standards raise the heel mounting platform higher than the toe, creating a slight "heel-to-toe drop", also known as aheel raise. This drop causes the skater to lean forward by default, simulating a subtleforward flex similar in purpose to thehi-lo wheel setup used in hockey skates.[71][90]
Wizard skating is named after the company Wizard Skating, founded by Leon Basin in 2014. This form of skating is characterized by flowing footwork from freestyle, slalom, andfigure skating, while a skater blazes through roads, rolls overcurbs, skates upramps, bashes downstairs, andparkours onwalls. Leon perfected a type of "wizard" skate for this sport, featuring a long frame, large wheels, and apre-rockered wheel setup for either 4 wheels or 5 wheels.[91][69] Skaters increasingly refer to this style as "flow skating".[46]
Hard boots dominated the inline skate market in the 1980s and 1990s at the inception ofmodern inline skating, andtraced their design back to plastic ski boots fromLange. They have an outer shell made ofplastic,fiberglass,carbon fiber, or other solid materials. A removable liner in a hard boot provides a snug yet comfortable fit between a skater's foot and the hard shell.[55][47][92]
Hard boots commonly use a combination ofvelcrostraps and plasticbuckles as closures. The cuff is usually secured with a top buckle. Some boots uselaces on the facing of the boot, while others have a front strap (or buckle) instead of or in addition to laces. The front lace and top buckle secure the foot inside the boot. To achieve properheel lock, the liner is shaped to fit the heel, and a 45° strap (or buckle) presses theinstep of the foot against the contour of the liner.[42]: 15–18
Hard boots have a high cuff (or shaft) to provide properankle support. In order to accommodatedorsiflexion, the cuff is made to pivot near theankle bones. As a skater leans their shin forward, the hinged cuff rotates to follow the lower leg while continuing to provide lateral ankle support.[42]: 15–18
Molds used in plasticinjection molding are expensive to make. As a result, plastic hard boots are usually available only in so-called "dual sizes". One hard shell is made for two US and EUshoe sizes (e.g. US 9-10, and EU 42–43). A thicker liner is provided for US 9 and EU 42 to fill the gaps, while a thinner liner is provided for US 10 and EU 43. Some manufacturers offer "dual fit" liners, where the same liner can accommodate two shoe sizes using elastic parts,memory foam, and other compressible space-filling materials.[55][42]: 15–18
K2 introduced soft boots to inline skating in 1993 with its Exotech line ofrecreational skates, marking the company's entry into the sport. Building on this innovation, K2 later released the legendary K2 Fatty, anaggressive skate featuring the same soft-boot design. Since then, similar soft boots have come to dominate the recreational skate market.[93][94]
They are akin tohiking shoes, made oftextiles,mesh,neoprene, and other soft materials. Liners are integrated into the soft boot, and are thus not removable or replaceable. A soft boot is reinforced in strategic areas with a plasticexoskeleton forstructural support.[47][92][42]: 15–18
A soft boot uses a pivoting cuff to support the lower leg, likehard boots. Otherwise, its exoskeleton covers only a small area of the foot. This allows the boot to providepassive airflow through its fabric for moisture extraction, to keep the foot cool.[55]
Soft boots useclosure systems similar to those of hard boots. These includelaces,velcrostraps, and plasticbuckles. Lacing the front of the boot is key to securing the foot within the boot, due to the lack of exoskeleton support in this area. On the other hand, the flexible front of the boot readily accommodates different shapes of foot. Soft boots thus provide a more comfortable fit at the expense of reduced rigidity and support, making them suitable for beginners and casual skaters. Committed enthusiasts, however, generally avoid soft boots due to their lack of direct and immediate response to skating moves, a result ofelastic hysteresis.[55]
Soft boots are lighter and generally more affordable than hard boots. They are also easier to manufacture in preciseshoe sizes. While hard boots typically come in "dual sizes", soft boots are available in "half sizes" for US shoe measurements (e.g., US 9.5, 10, and 10.5) and, in some cases, for EU sizes as well (e.g., EU 39.5, 40, and 40.5).[55][42]: 15–18
Hybrid boots, also known as hybrid soft boots, look superficially similar tosoft boots, complete with soft materials covering a large part of the boot. Unlike soft boots, however, hybrid boots have noexoskeleton reinforcement apart from the pivoting cuff. These boots have anendoskeleton instead, in the form of acomposite shell. The shell serves as the sole of the boot, with shell walls extending upward from the sole. The soft upper part of the boot is pulled taut over the shell and glued onto it.[47][55]
Hybrid boots are lighter thanhard boots and soft boots. Yet they remain rigid where the foot meets the boot. Integrated liners in hybrid boots can be made thinner than removable liners in hard boots. In higher-end hybrid boots, the integrated liner isheat-moldable for the best custom fit, and the shell is made ofcarbon fiber. A hybrid shell sits much closer to the foot than a hard shell or the exoskeleton of a soft boot. As a result, hybrid boots provide more direct and responsivepower transfer from a foot to wheels.[47][95]
Hybrid boots originated from the development of carbon shells inspeed skates during the 1990s and 2000s. In the 2020s, manufacturers like Powerslide offer hybrid inline skates, including models such as the Hardcore Evo, Tau, and Swell. However, the term "hybrid" has yet to gain universal acceptance, and these boots are often marketed as high-end soft boots.[47][96][97]
In the 21st century,hockey skates increasingly favor "one-piece" carbon boots with amonocoque shell that were first developed in the 1990s forspeed skating. These boots are unlike the three common types of inline boots:hard,soft andhybrid. The one-piece boots are built around acarbon fiber-reinforcedcomposite shell, where the shell almost completely surrounds a foot. After eyelet holes are punched out of a shell, the shell is usable as a functional boot if laced.[98]
For instance,Easton's Synergy 1300C came out in 2005, with a unitary shell made with carbon andaramid fibers. This is widely recognized as the first retail hockey skate with a composite shell.[99][100]Heat molding became possible in 2006, with the Easton Synergy 1500C.[101][102] Other hockey makers, such as VH Hockey, took it one step further, creating a single, unbroken composite shell that also incorporates the "facing" portion where eyelets are located.[95] A heat-moldable monocoque shell requires no breaking-in, unlike traditional hockey skates.[103]
True Temper Sports bought VH Hockey in 2016, and started to mass-produce retail hokey skates with heat-moldable monocoque shells, as well as scaling up3D scanning of feet at retail stores forcustom-molded True hockey skates,[103][104][105] leading to inline hockey skates such as the TF9 Roller Skate, and the TF Pro Custom Roller Skate in 2020.[106][107]
An inline skate frame, sometimes referred to as the "chassis" in certain disciplines such as hockey,[106] serves as the structural link between theboot and thewheels. It connects to the ground through the wheels mounted on it, and to the skater's foot through the sole of the boot.
"Frame length", also known aswheelbase, refers to the distance between the centers of the first and last wheel axles. In disciplines likehockey andslalom, skaters use short frames with closely packed wheels to enhance maneuverability and enable fluid footwork. In contrast,speed skating relies on longer frames, which space out the wheels to provide greater stability at high speeds.[62]
"Frame height", "deck height", and "ride height" are related but loosely defined terms in inline skating. All three describe how low a boot can be positioned relative to the ground in agiven setup, considering the number and size of the wheels. Ideally, a skater wants the boot as close to the ground as possible, while allowing enough clearance between the sole and the wheel tops for free rotation.[108][109] All three terms may refer to the distance from the frame's deck to the wheel axle center, excluding wheel size. In other cases, they are defined as sole-to-ground distance, incorporating both the structure of a frame and of actual wheel size.[T][62][110]
Frame rigidity is essential for an efficienttransfer of power from a skater's foot to the ground. A rigid frame does not suffer fromelastic hysteresis.[42]: 18–21 For this reason, even entry-level inline skates often usefiberglass-reinforced plastic, instead or softer but cheaper plastic to make frames. For a stiffer yet lightweight frame, aircraft-gradealuminum alloys such as the 6000 and 7000 series are used. Hockey and speed skating often call formagnesium frames, which are even stiffer and lighter than aluminum. Some speed skaters usecarbon fiber frames that are the most rigid and lightweight frames available.[71][111]
Rigidity of a frame is an important factor in choosing one. However, other considerations, including cost and weight, also influence the decision.[112] Sometimes, a discipline's needs trump many of these factors. For instance, aggressive skaters exclusively use fiberglass-reinforced plastic frames for their superior performance and consistent friction whengrinding against all types of surfaces.[45]: 138 Some of the most rigid frames, such as those made of carbon fiber, can be too brittle forhockey. These frames shatter rather than deform under impact or extreme stress due to their lowfracture toughness.[113] In addition, some skaters value comfort, which is at odds with rigid frames; increased rigidity transmits all imperfections of the road surface to the skater unattenuated, reducing comfort.[114]
Wheel rockering can be achieved by using wheels of differentdiameters, or by using a frame with built-in support for a rockered arrangement of identical wheels. Such rockerable frames may be configured in either aflat setup for long-distance skating, or abanana-rockered setup for highly maneuverable disciplines like hockey, with sharp turns and quick footwork.[36]: 81–86 [88]: 20–21
Some frames are compatible with specializedhardware for quick and reliable switching ofwheel setups. These involved the use of frame spacers, axle guides, mounting hole inserts, or axle bolts that fit oblong mounting holes in two ways. Such hardware can be toggled to shift the axle's center between two preset positions.[43]: 44–45 [U]
With the advent of mounting standards and easily swappable frames in the 21st century, some inline frames now eschew toggleable hardware in pursuit of reduction in complexity, weight, and number of components. Each brand offers its ownpre-rockered frame with custom axle holes to create a wheel arrangement that it deems optimal.[88]: 20–21 [59]
Modern inline skates began as off-season training tools forice skaters.[71]Early frames, including those used by the USSR speed skating team in the 1960s, featured adjustable lengths and variable wheel positions to fit different shoe sizes.[20] This approach continued in the 1966 Chicago Roller-Blade andearly 1980s Rollerblade skates.[C][V] Early inline skates lacked mounting standards. The 1962 USSR skate and 1966 Chicago Roller-Blade fitdress shoes with heels, while the 1975 Super Sport Skate, modeled after hockey boots, already had a raised heel mount on the frame.[D]
Non-standard frames still dominate entry-level skates and are often non-replaceable. Most lack adjustment forpronation orsupination. Some, like the 2024 Powerslide One Zoom, useriveted frames that cannot be customized.[71] Outside the entry-level market, most inline skates follow one of three mounting standards:UFS,165mm, orTrinity.[108][109] The exception ishockey skates, which still use riveted mounts like ice hockey boots. All hockey skates, from budget to high-end custom models, have proprietary, non-replaceable frames.[O]
In 1974, Inze Bont introduced fiberglassspeed skate boots with165 mm mounting holes for attaching adjustable ice blades.[71] As inline skating grew in the mid-1980s, brands like Darkstar,Mogema, and Raps created frames to fit these boots, establishing the first inline skate mounting standard: the "165mm 2-point" system.[116]
Later known as SSM (Standard Speed Mount),[117] this standard features a10 mmheel raise that enhances power inpush-offs through deeper ankle flexion.[63] The standard does not specify a frame width, mount width or exact mounting locations on the boot.[71] In practice, Bont boots offer only minimal mounting areas. But compatible and rigid frames can still be secured to a boot with minimal flex, especially with Bont's laterkevlar andcarbon boots.[118] Roces Impala skates brought the 165mm standard outside ofspeed skating in the mid-1990s, expanding it torecreational,aggressive, andslalom skating. However, softersoles in these boots may flex under load, prompting reinforcement with metal plates.[71]
Originally designed for five small wheels (e.g. 5x80mm), the 165mm layout caused bolt interference when 4x100mm setups withlarger wheels became popular, forcing frames to becometaller.[119] To address this, the "195mm 2-point" LSM (Long Speed Mount) was introduced in 2003.[120] It allows longer frames and larger wheels, while retaining the same heel raise, without adding additional height.[121] This design provides a stable ride at high speeds by maintaining a relatively lowcenter of gravity in proportion to the longer wheelbase.[122][62] While LSM is mainly used in speed skating, many frames now include slots to fit both standards.[89]
Aggressive inline skating gained mainstream attention after its 1995ESPNX Games debut, sparking rapid growth and development ofaggressive skates.[123] Released in 1996, theK2 Fatty was the first skate to integrate the frame into the soulplate, reducing height differences and replacing the traditional two-part platform with a solid rectangular structure.[124][125] In 1998, Roces released the 5th Element, an aggressive skate that combined the soulplate and frame into a single flat unit with no height difference between front and rear. This flat sole improved soul grinds and influenced other skate designs.[126]
In 1999,Salomon, USD, Razors, Kizer, 7XL/Able, and Fifty/50 developed the Universal Frame System (UFS), a standardized mounting system for aggressive skates. It used a flat rectangular surface41 mm wide with two holes spaced167 mm apart, aligning with the trend of flat soulplates. Salomon's 2001Aaron Feinberg Pro Model was the first skate to feature UFS and quickly became a popular industry standard.[60][127][128]
Unlike other mounting systems of the time, UFS eliminated built-inheel raise, positioning the heel level with the toes for the first time. However, most brands followed Salomon's lead in incorporating a thick shock absorber at the heel. This provided better impact support for hard landings from high jumps, but accidentally reintroduced a small amount of heel raise.[124][129]
The165mm standard, originally from speed skating, has dominated since the mid-1990s, except inaggressive (UFS) andhockey (riveted) skates. But its small mount area can cause frame wobble on boots without stiff soles or reinforced platforms.[71] As larger wheels became popular, 165mm frames adapted with taller designs or altered wheel placement to fit bigger wheels. Some raised frame height, reducing stability,[63] while others downsized or shifted middle wheels to avoid bolt interference.[130] Some brands shifted mount platforms, leading to front-back centering issues when mixing boots and frames.[119] Introduced in 2003, the195mm standard supported larger wheels without raising frame height or altering wheel placement.[120] However, its extended front-to-back spacing exceeded the optimal "heel-to-ball" length, requiring ultra-stiff soles not found outside thespeed skating market until the late 2010s, limiting adoption tocarbon-fiber speed speed boots.[84][131][132]
In 2016, Powerslide introduced the Trinity mounting system to supportmodern wheel setups while addressing the limitations of the 165mm and 195mm standards.[133] Unlike two-point systems, Trinity usesthree mounts. The two front bolts are offset, placed beside the centerline to allow front wheels to sit closer to the sole.[134] The rear mount, located under the heel, is raised by10 mm to clear the rear wheels and create aheel raise similar to the 165mm standard. The three bolts form a triangular layout measuring150 mm,135 mm, and55 mm.[90] This design aligns with foot anatomy for improved heel-to-ball support and structural stability.[62][131]
A Trinity frame typically wobbles less than 165mm or 195mm frames on similarly stiff boots. Unlike 165mm setups, which rely on the sole acting as acantilever around central bolts, Trinity distributes support across the full width of theball of the foot, similar to a hockey blade holder. This wider support reduces cantileverstress, improving power transfer and edge support.[135][136]
A Trinity frame typically has a lower frontmount height than its 165mm counterpart when using the same wheel setup. This is because the front mount of a Trinity frame can be positioned significantly lower than the tops of the front wheels due to its open centerline, allowing the front of the boot to be moved as close to the ground as the front wheels allow. This lowers the skate's center of gravity, improving control and stability.[110]
A heel brake is a hardrubber stopper attached to the back of the frame that lets skaters stop by lifting their toes and pressing the brake to the ground. It is especially important for beginners, offering a simple way to stop quickly and control downhill speed.Recreational and fitness skates usually include one brake, mountable on either skate, with most righthanded skaters choosing the right.[27]: 25–26
Heel brakes can interfere with advanced techniques likecrossover turns, which are essential inhockey andspeed skating. They also hinderfreestyle slalom tricks andaggressive grinds. As a result, skates made for racing, hockey, slalom, and aggressive skating typically do not include a heel brake.[137][42]: 30–38 Someurban skates include an unattached brake, while others cannot support one at all. Many experienced skaters remove heel brakes after learning other stopping methods, such as the "T-stop", which uses friction from dragging one skate behind the other. However, these techniqueswear down wheels, so some skaters prefer slalom moves and controlled turns to avoid obstacles and reduce wear.[42]: 87–96, 101–114 [88]: 24
Inline figure skates are unique among inline designs in that they use a "toe stop" instead of a heel brake. Toe stops are essential for performing manyartistic roller skating moves and jumps.[7]: 22–23
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Modern inline wheels are made ofpolyurethane (also PU or urethane), a versatileelastomer thattransformed skating.[138][139] It can bemolded into any shape and customized for color,hardness,grip, andelasticity, enabling specialized wheels for various skating disciplines.[140][W][142] Polyurethane offers high elasticity, orwheel rebound, without compromising other properties. This rebound helps convertstride energy into acceleration, benefiting all types of inline skating.[143][X][42]: 24–26
Before polyurethane,roller skates andskateboards used "composition wheels" made fromclay orrubber mixed withfibers.[144][Y][7]: 20–22 In the early 1970s, roller skaters tested polyurethane wheels but found them too grippy and slow forwooden rink floors, where composition wheels worked better. By the mid-1970s, skateboarders repurposed polyurethane wheels from roller skates, shaving them to fit. Their elasticity improved rides on rough surfaces and helped reviveskateboarding after its decline in the late-1960s.[147][148][149]
In the early 1980s, Scott Olson similarlyrepurposed polyurethane wheels from roller skates, shaving down tens of thousands to fit the skates sold by his company, Ole's Innovative Sports – later known asRollerblade. The same qualities that made polyurethane wheels ideal for skateboarding, such as durability, impact resistance, and a smooth ride, also benefited inline skating. This innovation helped bring inline skating out of obscurity and transform it into a popular outdoor sport during the 1980s.[31][29][20][140]
Modern inline wheels consist of two main components: an outer polyurethane tire, shaped like adonut, and an inner plastic hub, also known as a "core". The hub features a hollow center designed to accommodate a spacer and twoISO 608 ball bearings. Made ofhard plastic, the hub securely holds the bearings in place through afriction fit - something the softer polyurethane tire cannot achieve. On the other hand, the soft polyurethane tire is able todeform upon ground contact, cushioning the landing and gripping the ground.[115][W][51]
From the 1910s to the 1970s, many wheeled skates served asprecursors to modern inline skates. Most of these early skates featured small wheels made of rubber or rubber reinforced with fibers, often with relatively simple constructions.[19][21] In the 1980s, Rollerblade collaborated withKryptonics to develop polyurethane wheels for inline skates. The inline industry adapted plastic hub innovations fromroller skates, integrating them into inline wheels. These wheels weremanufactured by placing a plastic hub at the center of amold and then pouring moltenpolyurethane around it. The liquid polyurethane flowed into cavities and holes in the hub before settling. As it cooled and solidified, it formed a secure interlock with the hub.[U][Z][142]
The outer rim of a wheel hub, known as the "interlock", is buried within the polyurethane tire. Unless the tire is made from clear urethane, this rim remains hidden from view. Beyond mechanically securing the tire to the hub, the interlock rim also enhances the wheel's overallstructural rigidity.[AA][Z][150] Some manufacturers apply abonding agent to the hub before pouring the polyurethane, creating achemical bond that reduces reliance on mechanical interlocking. Others usepolyurethane-blendedplastic hubs that bond chemically with the polyurethane tire duringmolding.[W][151]
The visible hub size varies with wheel dimensions and skating discipline. In smallaggressive wheels, the hub is just a thin ring housing thebearings. In contrast,82 mmracing wheels from the 1990s had hubs taking up nearly half the diameter. By the 2020s, 110 to125 mm wheels feature hubs that occupy most of the wheel's diameter.[48]: 19–24 [42]: 26–27 [152]
A wheel'svolume grows with the square of itsdiameter given fixed width. Large solid wheels would be too heavy for inline skating, so designers adoptedstroller wheel concepts, using lightweight spoked hubs with interlock rims to hold the tire. These "spoked hubs", or "open cores", have an outer rim connected to thebearing housing by spokes. "Full hubs", or "closed cores", are solid discs with no visible separation. "Semi-open cores" fall in between, with solid discs and small hollows drilled to reduce weight.[153][140]
Spoked cores are generally lighter than full cores but may offer reduced rigidity and structural integrity. Aggressive skaters prefer small wheels with robust full cores for durability during jumps and landings. Speed and marathon skaters use large wheels with spoked hubs, which allow air to circulate around the hub, andhelp cool the bearings. Without adequateheat dissipation, the polyurethane tire may soften, increasingdeformation during rolling and potentially leading to separation from the hub.[51][115][154]
Inline skate wheels in the 2020s range from55 mm to125 mm in "wheel diameter", but the "wheel width" remains standardized at24 mm.[155][150] Frames are built for specificwheel setups, each fitting a set number of wheels of certain diameters, yet all assume a24 mm "hub width".[51][156] "Wheel profile" describes the shape of the contact surface when viewed head-on. Although any diameter can be matched with any profile, certain combinations work better for specific skating styles.[157][158]
"Small" wheels inaggressive skates, typically 55 to64 mm in diameter, often have a "flat" contact profile resembling a rounded rectangle likecar tires.[154] This shape provides stronggrip and stable upright rolling.[158] While flat profiles were popular in the 1990s, modern aggressive skaters increasingly favor slightly rounder profiles for better balance between stability and maneuverability.[159]
Most inline wheels are "medium-sized" with a "round" profile, since skaters often tilt their skates rather than always keeping them fully upright. Many techniques involveedging, or skating on the wheel sides, which requires a consistentcontact surface at various angles.[J][56] Round profiles support this, even if the contact area is smaller than that of flat wheels.Hokey andfreestyle slalom skates often use round-profile wheels up to80 mm in diameter.[157][150]
At the opposite end of the spectrum from the flat profile is the "bullet" profile, also known as the pointy, thin, narrow, or elliptical profile. It is common in "large" wheels from 90 to125 mm and often found inspeed skates.[43]: 51–52 [140][158][69] It helps skaters achieve two seemingly conflicting goals. The first goal is to maximize grip (orstatic friction) during deep edging, allowing skaters to convert lateralpush-offs into forward motion over a longer stride. The second goal is to minimize rolling friction (orrolling resistance) when upright, enabling longer, fasterglides with less energy loss.[51][50]: 316
"Large" wheels act likeflywheels, storingrotational energy that helps skaters reach and maintain high speeds over long distances. Theirgyroscopic effect stabilizes direction, reducing energy loss from lateral drift. However, their greater mass makes them slower toaccelerate.[51][42]: 24–25 In contrast, "small" wheels have lower rotational inertia, allowing faster starts and quicker maneuvers. They also lower the center of gravity for better control, but give a bumpier ride and perform poorly over bumps, cracks, sticks, and pebbles.[92][155]
Polyurethane wheelsdeformelastically under a skater's weight, which increases ground contact and improves grip. Thiscontact area, known as the "footprint", differs slightly from an unloaded wheel'sprofile.[52][51] The ideal deformation varies by surface. On slipperyindoor rinks with polished wood floors, softer wheels are better because they deform more and enhancetraction. On rough outdoorasphalt, harder wheels are preferred since the surface already offers enough grip with minimal footprint.[88]: 18–19 [152][160] Balancing grip is essential. Too little grip causes slipping duringstrides, wasting energy. Too much grip creates rolling resistance, sapping speed duringglides.[51][52]
Rolling resistance is generally higher with softer wheels because they deform more, while harder wheels require less effort to start rolling and maintain speed on smooth surfaces. However, "onrough terrain", hard wheels can increase rolling resistance by wasting energy as they repeatedlylift skater's weight over small bumps, thus offsetting their typical quick acceleration and higher sustained speed. Softer wheels, though slower due to deformation, absorb surface irregularities better and help minimize energy loss in addition to providing a smoother ride.[161][162][163]
Wheel deformation depends on the skater's weight, the wheel's hardness, and its temperature. While weight and hardness stay constant, temperature varies withambient conditions, surface heat, andbearings friction from high-speed skating. As temperature rises, the polyurethane softens, causing the wheel to deform more and reducing its effective hardness.[U][164][51]
"Wheel hardness" is measured on theShore A durometer scale, which ranges from 0A (softest) to 100A (hardest). Inline skate wheels usually range from 72A to 95A. Indoorhockey wheels are softest at 72A to 78A.Recreational outdoor wheels are slightly harder, between 80A and 84A. Freestyle slalom andurban wheels range from 83A to 88A, whileaggressive wheels are hardest at 88A to 95A.[48]: 21–22 [157][160][152]
Within the appropriate "hardness range" for an activity, softer wheels offer better grip for quicker acceleration during lateral strides, and a smoother ride on uneven surfaces, though they wear out faster. Harder wheels allow for higher gliding speeds, resist wear on rough surfaces, and offer a more responsive feel, but they can lead to a bumpier ride and some energy loss.[165][152]
Dual density wheels were developed to address the long-standing challenge of choosing a singlewheel hardness to meet opposing needs. Softer wheels provided shock absorption over rough terrain and better grip at deep edging angles, while harder wheels offered greater wear resistance and higher speeds on smooth, upright glides. Skaters had tocompromise, as no single hardness met both demands effectively.[166][167]
In 1997,K2 patented a "dualdurometer" wheel, later known as a "dual density" wheel, aimed at combining asmooth ride over rough terrain with thedurability andspeed of hard wheels. Unlike single-compound wheels, it used twopolyurethane layers: a hard outer tire (70A to 100A) for wear resistance and speed, and a soft inner ring (20A to 75A) to absorb shocks and vibrations.[166]
In 1997, Neal Piper and Tom Peterson of Hyper Wheels patented a similar dual-layer wheel concept, but used a triangularfoammandrel instead of a soft polyurethane ring. This design aimed to match the benefits of K2's dual-durometer wheels, while also improvinggrip during deep edging. The foam mandrel's shape preventeddeformation at the wheel's tip during upright skating, while allowing the sides to flex underangled loads, enhancing grip duringstrides and turns at about a 30° tilt.[52]
In 2004, Neal Piper patented a multi-density wheel that reversed his 1997 design by using a soft outer polyurethane layer (60A to 75A) over a much harder internal support structure (80A to 95A or more). First seen inVariant hockey wheels from Revision, and later in theRecoil andFlex lines, this design gavehockey playerstop speed without sacrificinghigh grip.[168][169][51]
Wheel rebound is theenergy apolyurethane wheel returns as it recovers its shape after beingelastically deformed. Though widely discussed, there is no consensus on how to rate it.[42]: 24–26 Unlike other wheel traits that depend on skating style or terrain, rebound is universally desired. Higher rebound is always preferred, if cost were not a factor.[160]
"High-rebound" wheels feel lively and responsive, helping skaters roll faster with less effort byconverting more energy from each push into forward motion.[143] "Low-rebound" wheels feel dead,absorbing energy like flat tires and requiring more effort to maintain speed, similar to walking on soft sand.[164]
Apolyurethane compound can be formulated with varying rebound levels regardless of hardness. "Hardness" affects how much a wheelcompresses under load, while "rebound" measures how much of that energy isconverted to aid forward motion. These are separate, distinct properties.[X]
Rebound can be measured using tests like theBayshore Resilience test, which compares rebound height to drop height, and the Rebound Resilience test, which measures percentage of energy return. These tests assess "polyurethane resilience", another term for rebound, but their quantification ofelasticity are not directly comparable. Inline skate wheels rarely list rebound in technical datasheets, and when they do, it's usually under vague labels like High Rebound (HR) or Ultra High Rebound (UHR).[170][156][150]
Inmechanics, rebound is closely linked toelastic hysteresis, its complementary property, which measures energy lost as heat during deformation and recovery. The two areinversely proportional: higher hysteresis means more energy loss and lower rebound.[171]
Rolling resistance (also rolling friction or drag) is a key factor limiting a skater's top speed. It opposes wheel motion and is mainly caused byelastic hysteresis.[50]: 316 [52] To reduce it, manufacturers design polyurethane compounds forhigh rebound and thus low hysteresis, which is especially important inspeed skating.[161][88]: 18–19
Skater weight and wheel hardness affectwheel deformation and footprint size, which influences rolling resistance. Speed skaters prefer hard,pointy-profile wheels to keep footprints small and reduce resistance, while gliding upright.Dual-density wheels were developed to minimize footprint while preserving comfort.[50]: 316 [52]
Terrain roughness also affects rolling resistance, as energy is wasted repeatedlylifting the skater over small surface imperfection. The need to cushion bumpy rideswithout increasing the footprint was another driving force behind dual-density wheels.[162][166][163]
Wheel diameter plays another key role in rolling resistance,especially on rough terrain. Larger wheels reduce resistance by smoothing out surface imperfections and lowering the angle of contact with small bumps. This reducesenergy loss. As a result, wheels between90 mm and125 mm are common inurban andmarathon skates, where both speed and handling uneven surfaces are important.[163][162][69]
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Ball bearings allow inline skate wheels to spin freely by separating the moving wheels from the non-moving structure.[172]Wheels rotate aroundaxles that are tightly bolted to theframe, which is securely attached to theboot using fasteners. Bearings minimizefriction between the wheel and axle, enabling greater speed with less effort.[42]: 26–29, 39–45 [AB] The adoption of modernISO 608 ball bearings, combined withpolyurethane wheels, helped propel inline skating toits peak popularity in the 1990s.[31][46]
An ISO 608 ball bearing has two concentric rings: anouter race attached to the rotatingwheel hub and aninner race fixed to the stationary axle. Between them are 5 to 8rolling balls.Deep grooves in the races form raceways that hold the balls securely. A retainer, or cage, keeps the balls evenly spaced along the raceways.[173][42]: 26–29, 39–45 [AB][174]
TheABEC scale rates bearingprecision from 1 to 9 (highest) in odd numbers, originally for high-speed industrial machinery. Higher ABEC ratings show better precision (or tolerance) but are only one of many factors in a bearing's suitability forinline skating.[42]: 27–28 [175] For inline skating, any ABEC-rated bearing is sufficient, considering that an average skater cruising on80 mm wheels reaches only about 1,326 RPM. This is just 3.5% of the mechanicallimiting speed (38,000 RPM) of ABEC 3-rated 608 bearings fromSKF.[AC][176]
However, ABEC does not account formaterial type,quality,durability, or how bearings handledirt,moisture, and other factors crucial for skating performance. Recognizing the unique demands of skating, George Powell worked with aSwiss manufacturer to develop 608 bearings specifically forskateboarding, launching Bones Swiss in 1983. Unlike standard bearings made forelectric motors operating inclean environments, Bones Swiss bearings were purpose-built and designed to withstandmulti-directional abuses from street skating.[177][178] They featured a serviceable outershield for easy access when cleaning. The inner side was left open, andmolded plasticretainers could be temporarily removed when accessing and cleaning theballs andraceways. Powell also created a customlubricant suited to skating conditions.[179][172][180]
Reputable skate bearing brands typically avoid ABEC ratings, as they don't reflect design features specific to skating. Instead, bearings are marketed under specialized product lines.Bones Bearings, for instance, offers Bones Swiss, Bones Swiss Ceramic, Bones REDS®, and Bones Big Balls®, all labeled Skate Rated™ to show they areengineered for real skating demands. Powell's “Swiss” design and engineering has become anindustry benchmark in both skateboarding and inline skating, though some imitation brands sell “Swiss” bearings that mimic the structure and claims without being made in Switzerland.[50]: 317–318 [88]: 22–24 [181][182]
Similarly, TWINCAM bearings were created in the early 1990s specifically for inline skating, marketed with the slogan “Beyond ABEC”. In 1991, they introduced serviceable bearings with removable shields held in place with aC-clip, followed in 1992 by TK CLASSIC Racing Gel, awater-repellent lubricant. In 2002, they launched the ILQ-9, a 6-ball bearing, as an alternative to the standard 7-ball setup. The ILQ line later expanded to include models such as ILQ-9 Pro with rubber shields, ILQ-7 forOEM skates, ILQ-X mr2 with reduced weight, and ILQ-Midget with 11 balls. TWINCAM trademarked "ILQ" (InLine Qualified) as a proprietary rating system, and had various ILQ models rebranded and redistributed by partners such as FR Skates,K2,Rollerblade, and Powerslide/Wicked.[183][184][82]
Skaters lose energy not only fromwheel rolling resistance but also from bearingfriction, caused by internal components like balls, cage, lubricant, and seals.[185][186] However, in clean,well-lubricated bearings, this friction is minimal compared to rolling resistance of polyurethane wheels. Mostpurpose-built bearings from reputable brands meet or exceed ABEC 3 specs, so bearing selection has little effect on performance when bearings are new.[162][176][50]: 317–318 [88]: 22–24
Bearing selection plays a significant role over thelifetime of bearings, however, because performance depends on how well bearings resist contamination fromdirt,dust, andmoisture. Evenmicroscopic particles can damageraceways and hinder smooth rotation.Contamination is the most harmful factor; it reducesefficiency or causes bearings to seize.[187][178] As skaters say, the fastest bearings in the world are simply ones that are new or freshly cleaned and lubricated.[179][175]
Inline skate bearings are protected fromcontamination using four mainshield types: (Z) non-serviceable metal gap shields, (ZS) serviceable metal gap shields with a C-ring, (RS) serviceable rubber gap shields bonded to a metal insert, and (RSL) full-contact labyrinth rubber lip seals.[172][AD][48]: 42–45
Z shields: simple metal covers that snap into the outerrace without touching the inner race, leaving a small non-contact gap. They create nodrag but offer limited protection and cannot be removed without damage. Bearings with shields on both sides are labeled "ZZ" and are non-serviceable (e.g., Rollerblade SG).[179][192][174][AD]
ZS shields: similar to Z shields, but feature a removableC-clip (C-ring), allowing for easy shield removal for maintenance. They are similarly non-contact and low-drag, and similarly provide minimal defense against dirt and moisture. Their main advantage is serviceability: that skaters can remove and reattach the shields without damage, enabling regular cleaning andrelubrication. This design is used inTWINCAM ILQ-style bearings, with double-shielded ones often labeled "2ZS" or "ZZS".[173][172][174][AD]
RS shields: use anitrile rubber shield bonded to a metal insert. In skating, RS rubber shields specifically refer to the design popularized byBones Swiss. They offer better protection than Z or ZS shields and are removable for cleaning and maintenance. Many skate brands use only one RS shield, leaving the inner side open and protected by thewheel hub, allowing easy lubrication access without even removing the shield.[187][190][191][174][AD]
RSL seals: full-contact rubber seals with alabyrinth lip profile that lightly touches the inner race, blocking dirt and moisture. These are used with "thick grease" for long-lasting protection with "near-zero maintenance", but cause more "bearing drag".[174][AD] Though they don't spin freely when unloaded, they perform efficiently under a skater's weight, when grease is forced away from ball paths as wheels roll. Dragon Bearings produces "2RSL" models with RSL seals on both sides.[185][190]
Skate setup, customization and tuning terms vary by discipline. For instance,urban skaters refers to four larger wheels (e.g. 4x90mm) and triskates with three large wheels (110 mm or more) as "big-wheel setups". In contrast,aggressive skaters consider anything80 mm or larger to be big-wheel.[193][194] On the other hand, large wheels are standard formarathon skaters, and a triskate under125 mm is seen as small and unusual. Terms like "big-wheel" and "triskate" also imply specificframe andboot designs, as setups with125 mm wheels need stronger frames and more supportive boots to handle increased speed and leverage.[68][82][194]
Awheel setup generally refers to both the number and size of wheels. Common examples include 4x80mm forrecreational use, and 3x110mm, popular with urban skaters in the 2020s. Older 5x80mm setups, once used inspeed skating, are now mainly seen in wizard skating.[69][91] Wheel setups also involve "wheel arrangement", which affects performance. Aflat setup has all wheels touching the ground. Arockered setup raises the front and rear wheels for a curved profile. Ahi-lo setup uses decreasing wheel sizes frontward (e.g.80-78-76-74 mm)), keeping all wheels grounded but raising the heel for a forward-leaning stance.[72][79]
Skaters can customize one boot with different wheel setups for various purposes. Ashort frame with80 mmsoft wheels suits indoor use, while a longer frame with larger and harder110 mm wheels works better for outdoor distance skating. Some frames, like the Endless 90, support both 4x90mm and 3x110mm setups. Even without changing the frame or boot, switching wheels with different hardness, rebound, diameter, or profile can significantlyalter the skating experience.[89][195]
An "axle assembly" includes the rods, screws, bolts, and bushings that secure a wheel to the frame. A "bearing assembly" has twoball bearings with a spacer and, when placed in a wheel hub with a tire, forms a "wheel assembly".[196][197][198] A "frame assembly" refers to all skate components except the boot and wheel assemblies. For recreational skates, this includes the frame, brake, boot-mounting hardware, and axle assemblies. In aggressive skates, it may also include H-blocks and parts for grinding.[198][199]
Inline skate wheels wear down with use and need periodic "rotation" and eventual "replacement". Front wheels andinside edges wear faster, especially on thedominant foot, thus usually the right foot for right-handed skaters. Uneven wear can distort thewheel profile, and severely worn wheels risk de-coring (disbonding fromwheel hub) during use.[42]: 45–50 [200]
Regular wheel rotation helps distribute wear evenly, extendinglifespan of the entire set. This includes "repositioning" less-worn wheels to high-wear axles to balance diameter differences, "flipping" wheels to even out lopsided edge wear from motions such aspush-offs, and "swapping" wheels between skates to address asymmetrical wear from foot dominance.[36]: 81–86 [156][201]
1-3/2-4 rotation is a common rotation pattern for four-wheel setups in the 21st century. It exchanges the first wheel with the third and the second with the fourth, repositioning them to balance diameter differences. Simultaneously, wheels are swapped between skates, flipping inside and outside edges to correct lopsided edge wear and foot dominance effects. Eventually, all wheels wear out and are replaced as a set.[42]: 45–50 [43]: 41–45
4-1-2-3 rotation is another common method, and it predates1-3/2-4. This was first documented in the 1985 bookRollerblades: Dryland Training for Ice Hockey. The front wheel moves to the fourth axle, while all others shift forward one position. The4-1-2-3 rotation lets each wheel pass through all axle positions, promoting even wear and enabling full set replacement when needed.[36]: 81–86 [201][156]
Hi-lo rotation eliminates abrupt changes in effective wheel diameters which occur with other rotation patterns when all wheels are fully-worn and replaced as a set. With this method, all eight wheels are removed, sorted by observed diameter, and stacked from largest to smallest. The two most worn may be discarded and replaced with new ones. Wheels are then remounted by increasing size, starting with the smallest on the front of the non-dominant skate, and ending with the largest on the rear of the dominant skate. This creates ahi-lo wheel setup that mimicsforward flex and maintains consistent ride height across rotations.[201]
Bearingmisalignment is one of the most harmful issues in skating, second only todirt contamination in bearings. When customizing orreplacing wheels, bearings must be re-installed carefully. Misalignment can cause wheels to tilt, roll unevenly, drag against the frame, vibrate, and overheat. This reduces performance, risks tire debonding, and leads to premature wear of bearings and axles.[202][203][42]: 39–45
In the 1980s,Rollerblade andKryptonics developedplastic hubs with precise, rigid "bearing seats" to alignbearings accurately. Each7 mm deep "bearing recess" matches the width of an ISO 608 bearing, allowing flush mounting withpress-fit.[115][204][205] This leaves a10 mm gap between two bearings mounted on a hub standardized at24 mm wide. This gap is filled by a "bearing abutment" molded into the hub to position and support the bearings.[51]
A ball bearing has two concentricraces that rotate relative to each other. The outer race is secured to the hub androtates with thewheel, while the inner race staysstationary with the axle assembly.[204] A "spacer" matching the10 mm bearing abutment fits between the inner races. Tightening the axle boltclamps the frame around the bearing assembly, creating a rigid structure that binds the axle, spacer, and inner races, securing them to theframe andboot.[115][48]: 19–24 [43]: 43–44
The bearing abutment and outer race of each bearing together define a "bearing plane". Bothplanes should beparallel and exactly10 mm apart, with the spacer and inner races meeting at these same planes. Proper "bearing alignment" means all thesegeometric relationships are correctly maintained.[115][204]
ISO 608 bearings in inline skates aredeep groove ball bearings (radial ball bearings), designed primarily to handleradialloads - forces appliedperpendicular to theaxle from the skater's weight. These loads pass from theboot through theframe and axles to theinner races and balls, pressing against the outer races. Radial load in skating is thus colloquially known as "vertical load".[206][207][177]
Radial ball bearings are also capable of handling a certain amount ofaxial load from both directions. These are side forces along the axle produced by maneuvers that involve adeep edge, such as turning,crossovers,power slides, power stops, and techniques like slalom or thedouble push. Axial load in skating is colloquially known as "side load".[208][207][181]
Somepurpose-built bearings, such as the Bones Swiss, are designed with larger internalclearance (gaps between the balls and raceways) to better accommodate side loading.[177][181][207] This enables increased "axial play" (or axial clearance), an intentional design and not a sign of lowerprecision. It allows the inner race to shift laterally relative to the outer race, changing thecontact angle between balls and raceways to better support axial loads without binding.[209][210][192]
Greater internalclearance in skate bearings helpsprevent binding during side-loading maneuvers. However, it creates an unevenload distribution, with only the bottom ball and its neighbors supporting the skater's weight. These form the "load-bearing zone", while the other balls remain unloaded.[211] As balls rotate through the bearing, they briefly enter the load-bearing zone and endurestress beyond theirdesign limits, accelerating wear.[212] At the top of rotation, balls lose contact due to clearance gaps, causing skidding, noise, energy loss, and more wear.[213] Uneven surfaces add shifting forces that, combined with the clearance, cause axle vibrations and worsenbearing misalignment.[192][211][214]
Bearing preload in inline skates refers to a specific type ofaxial load - that from clamping the inner race against aproperly sized spacer using the axle bolt,pre-tensioning the bearing balls at anoblique contact angle. This reduces or removes internal clearance, keeping all balls engaged and evenly distributing the skater's weight during wheel rotation.[209][211]
Preloading is especially useful inhigh-speed skating, like downhill racing, where it removesclearance gaps, reduces skidding, and minimizes axle displacement. This improves wheel assembly'sstructural rigidity, and increases skater's stability, precision and control.[209][215] By using a correctly sized spacer, the axle bolt can apply just enough tension to create a slight negative internal clearance (around-0.01 mm), the "optimal preload".[216][90] This delivers optimalload distribution and load-carrying capacity, minimizing wear and maximizing bearing lifespan.[215][212][217]
Short spacer:Manufacturing imperfections often prevent spacers fromperfectly matching the bearing abutment length.[W][204][51] If a spacer is too short, overtightening the axle bolt beyond the optimal preload tension can create excessive negative clearance, increasing friction and drastically reducing bearing lifespan. In severe cases, it may cause thebearing balls to bind and lock the wheels.[218][209][AE] To address this, aluminum spacers are made in various lengths so skaters can match them to each wheel's exact dimensions.[AF]
Loose axle: To fix over-tension from short spacers, some skaters mistakenly loosen axle bolts, thinking it relieves excess preload. While this may let wheels spin freely, it causes the spacers and inner races to rattle and skid, producing clunking sounds. The inner races are no longer clamped, leading tobearing misalignment and excessive wear fromside loads. This creates cycles of over-preload and under-tension, worsening damage.Omitting spacers exacerbates the issue, potentially causing bearings to explode under strong side forces.[42]: 39–45 [190][219]
Long spacer: If a perfect spacer isn't available, a slightly longer spacer is preferred over a shorter one, to avoid over-tension and excessive bearing wear. While a longer spacer prevents preload by not pushing outer races against bearing abutments, it still allows the inner races and spacer to be securely clamped. Without preload, however, the outer races rely solely onpress-fit against the bearing recesses, which may not hold under side loads. This can cause the outer races to shift, wear the hub's bearing recess, and lead to lateral wheel movement and clicking sounds during skating.[204][203]
Wheel setup can refer to various aspects related to the selection and configuration ofwheels. The total number of wheels and theirdiameter are often expressed in the form {number of wheels} x {wheel diameter in mm}. For instance, a commonrecreational skate setup is 4x80mm, which means four wheels, each with a diameter of 80 millimeters. Wheel arrangement patterns are typically named according to the profile formed by the wheels at their contact points with the ground. In aflat setup, all wheels maintain contact with the ground simultaneously. A classicrockered setup, by contrast, creates a banana-like profile along the bottom.[69][72]
A flat setup is the most common wheel configuration used on inline skates. The majority of skates are sold with this arrangement. In a flat setup, all wheels make contact with the ground simultaneously when the skate is rolling on a level surface. While not as maneuverable as arockered setup, a flat setup excels in disciplines that prioritize speed, stability, and long-distance efficiency. It is the standard choice forspeed skaters andmarathon skaters. Flat wheel setups are typically noted in the format {number of wheels} x {wheel diameter in mm}. For example, a common recreational setup is 4x80mm or simply 4x80, indicating four wheels, each with a diameter of 80 millimeters.[36]: 81–86 [88]: 20–21 [69][119][49]
A rockered setup, also called a "full rockered setup" or "banana rocker", involves altering the wheel alignment to increase maneuverability. In a four-wheel inline skate, this typically means raising the bottom of the front and rear wheels by about 2 millimeters, so that only the two middle wheels touch the ground when standing on a flat surface. This setup mimics the profile of anice skate blade, and is known as the "banana" rocker after its curved profile.[36]: 81–86 [157][48]: 28 [72][59]
A rockered setup generally produces the opposite skating characteristics of aflat setup. It offers much greater maneuverability and allows for quicker, easier turning.Freestyle slalom skaters andartistic inline skaters consider the rockered setup indispensable, as it enables gliding on just the front two wheels, the middle two wheels, or the rear two wheels, depending on the move. Having ashort frame in combination with a full rocker is optimum for achieving the highest maneuverability when skating. However, this setup makes it more difficult to maintain stability at high speeds, since the skater cannot glide on all four wheels at once and is more prone to wheel wobbles when skating in a straight line.[88]: 20–21 [42]: 29–30 [91]
A frame designed for a flat setup can still be converted into a rockered configuration by mountingsmaller wheels at the front and rear. For example, a standard 4x80mm flat frame can become rockered by installing76 mm wheels at the front and rear, while keeping80 mm wheels in the middle. This customization creates a2 mm height offset between the outer and middle wheels, mimicking the standard banana rocker profile. Skaters commonly notate mixed wheel sizes in millimeters, listed from the rear wheel to the front. The rockered configuration described above is typically written as "76-80-80-76".[88]: 20–21 [72]
Natural rockering can develop naturally onflat frames due to uneven wheel wear. Beginners often wear down front wheels faster, creating a natural hi-lo setup over time without needing different-sized wheels. Specific skating styles can also wear front and rear wheels more than the middle ones, forming a natural rocker. As wheels wear down, skaters can employ variousrotation strategies to either restore a flat setup or enhance the rocker.[201][130][156] Although natural rockering usually produces less than the standard2 mm height difference, many skaters prefer this subtle profile. "Big-wheel"urban skaters and wizard skating advocates often use factory-tuned,pre-rockered frames designed to mimic this naturally worn rocker with new wheels of same size. Wizard even named its classic four-wheel frame NR, after natural rocker.[220][91][79][221]
A front rocker setup raises only the front wheel, while the remaining three wheels stay in a flat configuration. This design serves as a compromise between afull rockered setup and aflat setup. A skater achieves greater top speed and improved stability with less wheel wobble on this setup, compared to a full rockered setup, bystriding and gliding primarily on the three rear wheels. At the same time, the raised front wheel helps guide the skate over uneven terrain in urban environments.[222][88]: 20–21 [72]
The hi-lo setup, also known as "HiLo", is commonly found inhockey skates. Hi-lo is technically aflat setup, since all wheels maintain contact with the ground when the skate rests on a level surface. The term “hi-lo” refers not to the wheel contact profile, but to the orientation of the boot. It raises the heel and lowers the toe, creating a "heel-to-toe drop" that encourages a natural forward lean. Thisforward flex promotes a more aggressive stance, enhances push-off power, and helps prevent backward falls. Unlike terms likeflat orrockered, which describe how wheels touch the ground, “hi-lo” describes how the boot is angled forward.[222][72][43]: 57–59
This forward pitch can be achieved through a combination of frame design and wheel sizing. Some frames have built-in height offsets, resulting in aheel raise, common in hockey skates and standard on165mm,195mm, andTrinity mounts. However, this lift increasesride height, which can reduce stability. To counter this, hi-lo hockey frames use lower axle positions and smaller wheels toward the toe, keeping the front low while preserving forward lean and keeping ride height low. A typical hi-lo frame is annotated as "80-80-76-76", combining better power transfer during push-offs with improved control and stability.[64][71][119][50]: 311–314 [42]: 18–24
Hi-lo setups with smaller front wheels are often marketed as providing quicker acceleration, while the larger rear wheels are said to help with achieving and maintaining top speed. While it is true that smaller wheelsaccelerate more quickly and larger wheelsmaintain speed more easily, these performance traits are not the reason for the hi-lo configuration. The smaller front wheels are used out of necessity - to lower the toe of the boot and preserve the forward pitch - rather than for their isolated performance benefits alone. In practice, the smaller front wheels trade top speed for a lower and more stable ride.[64][79][AG]
Many skaters casually refer to any mixed-size wheel configuration as a "rocker", which leads to the common but inaccurate use of the term "hi-lo rocker" to describe a standard hi-lo setup. This is a poor choice of words, as the hi-lo setup is a flat configuration. Some skaters also misuse "rocker" as a general synonym for "wheel setup", leading to additional confusion, such as referring to a flat setup as a "flat rocker".[72][AH][AI]
Hi-lo frames are not the only approach to achieving a pitched boot with a low ride height. For instance, ahi-lo setup can be created using a standardflat frame by fitting progressively smaller wheels from rear to front, with a typical hockey setup written as "80-78-76-74". This arrangement produces a total heel-to-toe drop of6 mm while maintaining full ground contact.[222][79] Instead of purchasing wheels in different diameters, a skater can gradually create a hi-lo setup through ahi-lo rotation strategy, by placing the most worn at the front and the least worn at the rear. This approach minimizes noticeable changes in ride height between rotations, offering a consistent skating feel over time.[201]
Similarly, speed skaters seekforward flex while usinglarger wheels, which raiseride height. To low center of gravity, some165mm frames shift the second axle or use a smaller second wheel to lower the front.[84][63] Similarly, the ROCKIN' MIX4 100/90 frame uses smaller middle wheels and adjusted axle positions to form a100-90-90-100 setup, keeping the boot closer to the ground.[130][91]
TheTrinity system takes a different approach, with two front mounting points placed off-center, clearing space above the front wheels so they can sit closer to the boot. This allows setups like the Endless Trinity 90 with 3x110mm wheels to position the toe just110 mm above the ground.[119][110] Wizard Skating frames, using theUFS standard, achieve forward pitch by sloping the frame's mounting surface, despite using equal-sized wheels. However, UFS-based setups usually result in a higher ride height compared to Trinity.[91][221]
A new variation of rockered skating emerged in the early 2010s, led by a new generation ofaggressive skaters who rediscovered the benefits ofrockered setups, this time using larger wheels on longer frames.[91][69] Wizard Skating became a key influence. Its frames are made for flatUFS boots but feature a sloped mounting surface that creates a slightforward lean, similar to ahi-lo flat setup. The Wizard NR series is "pre-rockered" with a mild banana rocker named after thenatural rocker. The NR90 model uses four equal-sized wheels in a90-90-90-90 rockered layout.[221]
Similarly, the Endless Blading 90 frame is pre-rockered to support four90 mm wheels. This setup, branded as the "Balanced Rocker", is another mild version of the banana rocker. The frame uses the165mm mounting standard, with a built-in forward lean.[223] Another example is the Ninja NN 90 frame from NN Skates, which also features a pre-rockered design. It introduces NN Skates' proprietary "V.m Rocker", short for "modified V Rocker". The 165mm andTrinity versions come with built-in forward lean.[224]
All of these "pre-rockered frames" are variations of thefull rockered setup, combined with built-inforward flex. However, they are sometimes marketed using simplified illustrations that "horizon-correct" the top surface of the frame, showing the boot level and the skate pivoting primarily on the third wheel. This artificial stance is often described as a "V-shaped" wheel-contact profile, a "V rocker", or a "3rd-wheel down" configuration. In practice, however, skaters do not glide on a single wheel. Instead, they roll on two wheels at a time, such as the 2nd and 3rd, where the boot naturally tilts forward like a hi-lo setup.[59][91][225][221]
Some skaters therefore refer to this combination of forward pitch and rocker as the "hi-lo rocker" or "full hi-lo rocker". However, these terms can be confusing, especially since "hi-lo rocker" is also used colloquially to describe standard hi-lo setups. At present, there is no consistent term for this combination of banana rocker and forward lean in a pre-rockered frame.[72][201][AH][AI]
The anti-rocker setup is the most widely used wheel configuration inaggressive skates. It gets its name from being the opposite of arockered setup. In an anti-rocker configuration, the two middle wheels are raisedoff the ground, leaving only the front and rear wheels to make contact on flat surfaces. The middle wheels are typically spaced farther apart than in standard four-wheel setups, and are often made of harder materials with minimal grip. These hard wheels are commonly referred to asgrindwheels, antirockers, or anti-rocker wheels.[72][73] They are designed for one task alone: to makegrinding on ledges and rails easier.[70][226]
The freestyle setup is another wheel configuration favored byaggressive skaters. Despite the name, it is unrelated tofreestyle slalom around cones or freestyle skating on flat ground free of street obstacles. This setup featuresonly two outer wheels, with the middle portion of the frame replaced by solid material that resembles an extendedH-block, optimized for grinding.[70][73]
Fifty-50's Balance Frame introduced a convertible design that can use either grindwheels or juice blocks in the center. When juice blocks are installed as grind blocks, they fill the space between the frame walls, extending the H-block to form a smooth, solid grinding surface. This transforms the Balance Frame from ananti-rocker setup into a freestyle setup.[227][73]
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