Benefits of instability
Portuguese outsole developer Aloft has worked with technology and research partners in Spain to produce Sphair Air Bubble, an outsole that makes a virtue of unevenness.
Technical outsole developer and producer Aloft has worked with Pamplona-based footwear technology provider Semic and the University of Navarra in Spain to make a new system they have called Sphair Air Bubble. According to Aloft chief executive, Pedro Castro, what sets the new system apart is that, here, the partners have worked out the mechanics for creating “a certain instability in the outsole” that will be of benefit to the wearer, while maintaining a strong foothold on the ground.
Sphair consists of what he calls “a typical thermoplastic polyurethane (TPU) outsole”, but one that he insists is “different from the ordinary”. There are, for example, cleats on the bottom that have an unusual shape. They are narrower at the top, where they meet the outsole, than they are on the bottom, where they come into contact with the floor of a building or with the earth. Mr Castro says this allows the sole to flex freely no matter how wearers put their feet on the ground. Spacing of the cleats will allow water or oil or any other liquid to run off the outsole easily while grip is always maintained.
Striking features
Another striking feature is that, at the heel, two big, airbag-like bumps protrude from the outsole. These are the bubbles that form part of the new products name. To keep these airbags full of air, Aloft and its partners have welded a thin TPU membrane onto them. This offers lightness, plus shockproof and rebound capabilities.
“The real secret is inside, though,” Pedro Castro continues. “If you look you will see that the outsole is full of small cell-structures, designed and conceived in such a way that, while you walk, you will flex these cell-structures and they will absorb most of the pressure you are applying.”
This works in parallel with the cleats. These bend readily, but they are completely hollow and this, with the ability of cell-structures above to absorb pressure, provides what he calls “a superb cushioning effect”. A variety of categories of footwear will benefit from integrating the Sphair Air Bubble, the partners believe. They have, for example, received an approach from a sports brand that wants to try the idea in indoor sports shoes. Children’s sports clubs are going to take part in a trial. Aloft will collect a range of data and share it with its partners in Spain so that they can carry out any fine-tuning necessary.
Fine-tuning
“One of the big advantages we have at Aloft,” the chief executive says, “is that we have our own laboratory, which allows us to manage material development well. We can formulate different grades of rubber and specific grades of TPU.” He explains that this means the soling technology provider has the ability to engineer specific outsole features to meet customer requirements. The fine-tuning can apply to what he calls the geometry of the outsole and to levels of comfort.
Sphair Air Bubble is, Mr Castro claims, perhaps the first outsole ever designed with as much thought going into the interior of the outsole, its inner workings, as into the outer part. “You can only grasp the full potential of it when you see both systems working simultaneously,” he continues. “You only need to walk with a shoe that has this technology to feel immediate comfort. Imagine that you are walking on clouds.”
Another possibility that has come to light is the idea of using a different material on the back part with a view to obtaining an increase in the product’s shock-absorbing potential. At the same time, Mr Castro says there would be less elasticity at the front, allowing the wearer to have a more “self-propelling” walk. “We can achieve this by having two material flows inside a mono-cavity,” he explains. “We have developed software to control our machines and help us design where we want each material to flow and then we re-melt one over the other.”
One by one
At the end of 2020, at the time of the Safety Footwear Revolution Week, of which Aloft was one of the organisers, there were several prototypes already in place. Mr Castro said these prototypes showed delegates the unevenness of the outsole, with the cleats protruding to slightly different heights, while retaining their softness and their ability to “collapse” easily with the application of any pressure at all, even the prod of a finger.
He explains that the purpose of this is to have the cleats come into contact with the ground one by one when the wearer is walking. This means the outsole of a shoe or boot can adapt its height to the stance of the wearer and to the terrain underfoot and it is this that delivers the “walking on clouds” effect.
“Brands can use Sphair Air Bubble to co-create, with us, something of their own,” the chief executive concludes, “something in keeping with their brand genetics and their brand strength.”
The cleats on the Sphair Air Bubble outsole protrude at slightly different heights. Aloft and its partners insist there are benefits from this inbuilt unevenness and that wearing shoes that integrate this innovation is like “walking on clouds”.
All Credits: Aloft/Safety Footwear Revolution Week
