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From Quad Roller Skating Wiki
In this essay about quad roller skating I have mixed technical description with prose. This may seem a strange combination - yet art and science come together in a delicious and unique way with quad rhythm dance skating and I am trying to capture how both qualities fold into each other to make magic.
Quad Roller Skating; 4x4's; Freestyle Rhythm Skating; Non-Competitive Dance Skating; Old School Funk Skating; Roller Dance; Rhythm Stride Skating; Rhythm Styling; Gyroscopes; Biomechanics; Laws of Motion
Contents |
Introduction
This essay is an attempt at documenting a variant of Quad Roller Skating that has not, to my knowledge, heretofore been explicitly described or recorded. The target audience is primarily the Quad skater and will mostly be of interest to them. Not meant to be an all-encompassing explanation of how skates work, my thesis covers the basics and points out some special aspects of Quads and how they power and drive indoor dance skating. More than just a technical description, it explores how the science of moving bodies and machines underpins and dovetails with the artistic expression of a singular skating style only made possible with Quad Roller Skates.
Magic Machines
There is something extraordinarily fine about Freestyle Rhythm Quad Roller Skating. Done to skateable music* it can evolve into a form of dancing-on-wheels - a non-competitive, non trick-oriented flavor of Roller Disco, Jam Skating and Rollerboogie**, that interprets the music in a manner that awakens a rare magic pleasure and sense of freedom. Though it is seldom considered or understood, it is the peculiar combination and quality of forces produced on traditional quad skates that is behind this magic.
* Having a pace that respects body rhythm, the natural biomechanic speed range, ~ 30 to 90 strides per minute.
** These forms of Dance skating involve using some combination of Handwork (moves made while placing hand/s on floor or other supports during acrobatic moves) and Groundwork (moves with body being close to floor or grazing it) along with Floorwork (moves with wheels in full contact with floor) and Legwork (moves executed with skates, one or both, completely off the floor). Pure Freestyle Rhythm rarely if ever uses Groundwork and no Handwork, except in the sense that one usually moves their hands/arms in stylistic manner to the music. Legwork and Floorwork, alone or combo'd, are the Freestyle Rhythm skaters mainstay. Also, Jamskaters often are stationary when doing moves, not moving down the floor. These are key distinctions to keep in mind when trying to understand the differences between Rhythm and Jam.
The Wheels - Swinging Gyroscopes
When considered through mechanistic Newtonian physics and the laws of motion, moving Quads can be described as a system of two horizontally and geometrically aligned sets of 4 speeding gyroscopes, harnessed to and tugging on, slightly influencing and distorting each foot-move. They amplify movement at ankle, knee and hip - stretching body-english and increasing the striding and gliding skater's kinetic energy and forward inertial balance. The size of the centrifugal force produced is proportional to the mass of the wheels multiplied by velocity. Heavier wheels, then, will produce a greater force (Angular Momentum) (a set of 4 precision wheels with bearings can have a combined weight ranging from ~ 1/2 to 1 lb). All biomechanic pivot points (joints), each having 6 degrees-of-freedom of limited range, combine to assist and influence pendulum action and controlled whipping of the free leg, as the skater's center of gravity shifts from stride to stride.
The spinning wheels respond, as if by magic, to any rotational force applied round an input axis that is perpendicular to the axis of rotation, with a reaction force rotating about an output axis. This reaction force is always at right angles to the input force and axis of rotation. (see Gyroscope). In effect, if I rotate my leg clockwise, my foot (being held perpendicular to my leg) will simultaneously be pulled clockwise round it's length. Each flick of the ankle, each point of the toe now carries new weight. Gestures expand by the force of motion and the wheels take on a life and will of their own.
By comparison, in-line skate wheels, which are narrow and lighter, line-up in a single rigid row and produce much less centrifugal force - and of a different quality. This partly because unlike quads, as a group they are off-set on one axis only. The planar, horizontally-spaced quad wheels, gaining and regaining spin with each new stride, display their special Newtonian effects and reveal the first fundamental difference in the expression of mechanical physics between quads and all other skates.
The Quad Skate - Simple Mechanism, Complex Motion
The quad's double-action truck-design produce a geometry-of-motion that pivots on a line drawn between the center of the truck yoke and the ball of the pivot pin – this line forming an angle with the horizontal plate (the Action-Angle). The yoke is supported on the elastomeric action-cushions, in effect compression springs, that allow the trucks to tilt round the Action centerline while independently adjusting to irregularities in the floor, dampening vibrations and self-aligning. The front and back trucks are mounted mirroring each other, heel to toe. The combined converging sweeping motion of the axles (the double-action) describe the geometry behind the quick turns, natural foot articulation and easy rubber-leg'n. By pressing harder on heel or toe, the trucks can be at different angles at the same time, creating dynamic asymmetric free curving and deep edging.
The skate-cushion set-up - how tight or loose the skate action will be - is adjusted to match the skaters weight and style of skating – required fine tuning. There are a variety of cushion materials and hardnesses to choose from as well. When in the default unloaded condition the axles are parallel and the cushions evenly compressed. Turning shifts compression to one side and spring-loads the wheels against the floor as they try to return to their neutral position. This stored energy throws yet another force into the inertial mix.
It is important to note that the front and back axles pivot towards each other on the side that is being pressed, so that the wheels can stay in full contact with the floor, if desired, while the foot tilts. Together these defining qualities are unmatched by ice or in-line skates and are the second fundamental difference in the expression of mechanical physics setting quads apart from other skates.
Performance Skates - Quality and Precision
Serious skaters can appreciate high-quality skates, outfitted with high-speed ball-bearings having internal clearances especially designed for roller skating and lubricated with water-thin oil for minimum drag. They also have steel adjustable ball-and-socket pivot-pins for precise positioning and solid, repeatable rotations. There are skates with different action-angles which give quicker or slower turning action – that is, the amount of turn relative to the amount of foot-lean or how sensitive the skates are. The other important variable affecting turning is whether the action is centered primarily over the pivot pin or the action cushions. Mounted on truck axles and precision-machined aluminum-centered wheels, the bearings are protected from speed-robbing compressive forces. Assembled they form an unrivaled skate-to-floor footprint that is wide and stable in nature (~ 5 x 6 ½ inch). This is another important distinguishing feature.
The Boots - Muscle to Metal
The aluminum trucks, hangers and skate-plate are attached to professional-quality leather boots which have the proper flexibility for skate-dancing and are laced-up to allow easy ankle movement. Good ice and in-line skates generally don't permit much ankle movement. This looseness is appropriate for non-competitive quad dancing. Less so for roller hockey, jumping or crashing - which create high impact forces and over-flex - where more ankle support and rigidity are needed. Boot models with raised heels are an advantage as they push body weight forward onto the balls of the feet for deeper edges and better control during quick steps and changes of direction. Good boots have a steel brace inbedded and when attached to the plate forms a rigid triangular brace. Boots are positioned on the skates so that a single vertical line passes through the center of the ankle and rear axle – this gives optimum control and balance. Man and Machine are now calibrated and in alignment. Now comes the ritual lacing of foot-n-boot bondage, the leather-to-metal marriage of biomechanic and mechanical worlds – both equally controlled by the same laws of physics. The skates have become special body extensions.
Man Music and Machine – The Mixture Ignites
With steady bassy beat a sweet funky tune stokes a rolling wave - a master metronome of bio-rhythmic accent and meter. Up to speed, moving to the music, physics plays it's role. As she spins her magic a pleasing physical feedback and multiplying free-boost appears. Obedient to the beat, a kind of Shadow Skating spontaniously starts to form - a loosely-synchronized close-quarter communal dancing, ad libbing while flying through space.
Riding a rolling wave, skaters sync and weave across the floor like free-flowing schools of funky fish – swept-off on a pulsing tide of sound
Quad Roller Skates, these seemingly simple machines, are brilliant and subtle vehicles for controlled human motion. The Newtonian dance made with them - the skater's step creatively expressed, time-shifting and stretching in the wind of his speed, elegantly joining with willing partners – physics, biomechanics, beat, roll and soul – is fundamentally what give this little-known subset of social skating its uniqueness and charm. Tano 01:33, 16 October 2008 (UTC)
Licensing
G. Lavigne GFDL cc-by-2.5 Attribution required
