Recent technological innovations for skate wheels
Of all materials... PU is the best
Polyurethane (PU) is a plastic composite material (thermoplastic polymer) used in the manufacturing of inline skates. It was used for the first time in 1979 in the making of rollerskate and skateboard wheels. Since then, it has spread to all models, with but a few exceptions (tires on specific all-terrain models and very low range skates).
Beforehand, wheels were made of wood (box wood for speed skating), ivory, metal, rubber... even tires. They wore out quickly or transmitted vibrations too much. The use of PU enabled to mix flexibility, comfort and resistance to abrasion.
Some low range products distributed in supermarkets have PVC wheels. That material is hard and provides rudimentary rolling comfort.
The segmentation of the market
The use of polyurethane, a material that is easy to produce and transform, encouraged a real segmentation of the market. It was then possible to design wheels that met the users' needs according to their practices: hard, soft, small diameters for ramp skating, or soft and big for fitness and speed skating, notched for all-terrain skating...
Aesthetically speaking, the production of transparent wheels also widened the variety of choices for the users.
As for the number of wheels, let's say that for most practices, the dominant design stabilized with 4 wheels. Their number only varies in speed skating (from 3 to 5 wheels) and aggressive skating (2 or 4 wheels). A few brands launched 3-wheel skates between 1997 and 2000: Rollerblade with the Perseus and the Coyote, Spin with the Cros, Roces with the Big Cat S.A.S... Today, 3-wheel set-ups may make a comeback with the 3x125 mm in speed skating.
Aggressive wheels get bigger
Each discipline has its own wheel profile, with their specific core and on-core. For example, the special features of aggressive skating require flat wheels of small diameter, that are hard and have solid hubs. For several years now, aggressive wheels have become slightly softer (3 shores in 3 years, between 1997 and 2000) while their diameter has increased between 2004 and 2014.
Fitness skating in the stream of speed skating
Fitness wheels have become bigger throughout the years, just like speed wheels. Before 2000, most models were between 76 and 80 mm. Today, 80 mm is the smallest diameter available for adult skates... and diameters can go up to 110 even 125 mm!
All-terrain skating has found a second youth
All-terrain skates show various originalities linked to their use. Brands cleverly play with stereotypes to attract consumers. Polyurethane doesn't reign supreme here.
The 'resizing' of the wheels remains the major distinctive feature of all-terrain skates. The number of wheels varies from 2 to 4, but 3 seems to be the current standard.
Rubber is used for its adhesion and flexibility features on damp grounds. It is grippier than polyurethane on wet surfaces. In order to get more grip on various grounds, some brands briefly had a go at notched PU wheels, the efficiency of which is still debatable!
The average diameter that could be found on models released between 1998 and 1999 were close to 105 mm, against 82 mm for the biggest fitness wheels referenced at the time. Today, the only available model has 150 mm wheels. In all-terrain skating, diameters have varied between 90 mm for the Outback and 150 mm for Rollerblade's Coyote or Powerslide's Vi SUV.
What about wet grounds?
Only a few brands have addressed the problem of grip on wet grounds. As far as we know, Continental opened the way. The patent seems to have been bought by K2 in the following years.
P.S.I. also designed skate models with black rubber wheels, with efficient grip on wet grounds. The brand doesn't exist anymore today.
In 2011, MPC picked up the torch with the well-known Storm Surge, a model that offers great grip in the rain.
The main drawback of rain wheels is that they stick too much and wear out fast on dry grounds.
Bi-density wheels (K2)
That new concept on the market of inline skating was the object of several patents, including one that was registered by K2 in 1997. The principle is based on the use of two different densities of PU in the manufacturing of the on-core.
Inflatable PU skate wheels
Sports Premiere Magazine mentioned the creation of inflatable PU wheels by Hyper. They would have been displayed at the 1999 Chicago Exhibition. That type of wheel would adapt to all types of terrains and practices, with a simple pressure adjustment.
Yet no model equipped with those wheels could be found in any suppliers' catalogues of year 2000.
At the same time, Hyper released a polyurethane wheel with an air tube inside of its hub. We haven't been able to find any trace of it since then...
Hub efficiency, solidity and rigidity are constant concerns for manufacturers.
Aluminum imposed itself as a simple but efficient solution, but its limits are to be found in the comfort provided by the wheel. This type of product was briefly available in speed skating (P.S.I. with Intzcore), in freeskating (P.S.I.) and in aggressive skating (Exile).
Aluminum rims provide far superior rigidity and solidity to that of classic materials but they don't bend. They are stiff, hardly comfy and cause premature wearing of the polyurethane that undergoes all the stress. Aluminum skate wheels are often a little heavier and may distort in case of shock. Last but not least, their high production cost limits their entering into the market.
In the department of curiosities that fell into oblivion, in 2000, Hyper designed a balancing system to reduce the tacking of wheels at high speed. The principle lied in the insertion of a weight in-between the rims of the hub, just like for car wheels.
In keeping with aluminum rims, some brands like Hyper (again) launched wheels with carbon hubs, like the Helium model, for example. The additional cost of that technology is not negligible, but the rigidity and the weight gain are quite important.
The OCRA wheels
Speed skating, a discipline in constant search for more performance, saw the Korean brand O.C.R.A. enter the market with singular wheels.
The special feature of those wheels was that they had balls wedged by springs in the rims of their hubs. Inertia and centrifugal force would drive the balls would towards the outside of the hub, thus increasing the gyroscopic effect of the wheels. According to their creator, the performance gain would come close to 2 to 3%.
2006 was the year of lenticular wheels. The speed-fitness Fila collection briefly experienced the concept. Even if concept's efficiency is still to be proven, the brand has equipped its key product with them.
In cycling, lenticular wheels are used to improve aerodynamics but results are not conclusive and this technology is destined to disappear in favor of paracular and spoked wheels.
A few innovations specific to aggressive skating
Anti rockers are ersatz wheels. They are small fixed wedges in-between which you can stall on bars. They considerably improve the sliding. They prevent from being stuck during the execution of a trick.
Wheels without hubs appeared because aggressive skaters only use hard wheels of small diameter. It is thus not necessary to insert a very rigid structure to fix the bearings.
Wheels with aluminum rims were mentioned above. The Exile brand designed models with reusable aluminum hubs: Once the urethane worn out, you can buy new on-cores in your skate shop.
Hockey and freeskate
The hi-low setting consists in placing the skater's balance to the front in putting bigger wheels at the heel and smaller wheels at the toes. It provides a more reactive skating and better accelerations.
In freeskating, solid wheels also exist. They do have hubs, but they are not hollowed. Here again, the aim is to gain in rigidity and reactivity. The Hyper Concrete wheels are designed according to that principle and meet quite a success on the market.
Slalom rockered set-up
After the hi-low, we couldn't skip the rockering! The two middle wheels are bigger than the ones in the ends. That setting has an increased maneuverability and enables the execution of shaper bends.
What innovations in the future?
As seen above, no major innovation has really occurred since the use of polyurethane in the manufacturing of on-cores. Wheels seem to have reach some kind of standard design. Most of the wheel modifications can be seen as optimizations, according to the practices they are used for.
The next challenges that manufacturers could take up are varied: They could design a wheel with both a great grip in the rain and great performances on dry grounds. Design difficulties are the same in all practices: gaining in solidity without gaining in weight, optimizing the weight without losing in inertia, improving performances without sacrificing comfort... One may wonder if skating will remain a market flourishing enough for brands to really invest in research and development...
Useful linksTexte : Alfathor
Translation: Chloe Seyres
Photos : Alfathor