Daniel Barel's initial objective was straightforward. He wanted to make life more comfortable for people who are confined to wheelchairs. Curbs, different surfaces, and the energy required to propel a wheelchair took a tremendous toll on one of Barel's friends, who had tried his own hand at an improvised solution for the discomfort.
After an unsuccessful start, Barel refocused his energy on reinventing the wheel. The result is SoftWheel, a business based in Tel Aviv, Israel, that incorporates in-wheel suspension technology to help wheelchair users absorb shock and vibration. The company has seen double-digit growth in sales since the product became available in the United States in 2016. And the company is not stopping there. Barel and his team are working to adapt the technology to bicycles, airplanes, and automobiles.
“Even today, when we try to be have more places that are wheelchair accessible, it is still a challenge,” Barel says. “SoftWheel provides much more freedom to a user to go wherever they want.”
Putting the Focus on the Wheel
When Barel started his company, the initial work focused on improving the suspension of the chair. “Suspension at its core is very limited. It hasn't evolved a whole lot in the past 90 years,” he says. “No matter what we tried to do in putting suspension inside the wheelchair simply didn't work.”
The team funding Barel's early work threatened to pull its support. Barel and his team of engineers and designers went back and looked again at their mission. It became clear where they had to focus their attention. “It's just wheels and a chair,” Barel says. “We knew we couldn't put the suspension in the chair. There was nowhere else. We said let's put it in the wheel.”
The challenge engineers faced in designing the product came in controlling the movement of the wheels efficiently and effectively to limit the impact on riders. Engineers worked for nearly two years to develop the suspension technology to control the movement of the wheel and reduce the vibration on the chair. “We met many challenges in the development of the suspension technology,” says Yoav Satz, product manager for SoftWheel, “such as connecting the suspension system to the rim and designing a new hub with unique characteristics.”
SoftWheel's key technology lies in a triangular hub. It connects to the wheel with three suspension arms and will absorb shock from any direction. “All the magic happens inside the hub,” Barel says. The In-wheel™ suspension allows the hub to move freely within the diameter of the wheel. The wheel stays rigid, but the hub within it moves.
Four Trademark Technologies
With its In-wheel Suspension™, SoftWheels include three other trademark technologies. Its patented Adaptive Rigidity™ keeps the suspension arms rigid and strong like spokes, but automatically compress to absorb shock when they encounter obstacles. After impact, the suspension arms reset quickly and absorb almost all of the shock. With its Rapid Shock-Reset™, the suspension arms are ready to roll after just one-third of a turn of the wheel.
“It's a breakthrough in how you look at suspension,” Barel says. “It is selective. When you don't need it, it does not work. Only when needed will it spring into action and make those movements.”
SoftWheel's technology is demonstrated in a video of a drop test compared to a common wheel. In a drop of 15 cm with 110 lb of weight, the common wheel returns to a stable position in 10 seconds. The SoftWheel takes just two seconds to become stable.
The final piece to the SoftWheel puzzle are single-piece Rigid Rims™, which are built extremely rigid and strong. They offer as much stability and as fast a ride as the highest-quality regular rims on the market.
Some wheelchair manufacturers have tried to make smoother rides for users, but SoftWheel's three-arm suspension technology takes the focus away from the chair and onto the wheel. “The in-wheel suspension activates only when needed,” Satz says. “The technology enables the wheel to act as a rigid wheel over flat surfaces, thereby conserving a rider's energy and maintaining forward momentum (and reducing bounce on flat surfaces). It activates and acts as shock absorbers when the wheelchair encounters an obstacle or rough terrain, thereby reducing shocks and vibrations.”
Satz says springs or suspension that are used in some wheelchair frames do not achieve the same riding stability for users as the SoftWheels. “Our technology works no matter the angle of impact from the obstacle,” he says. “And the suspension shocks reset immediately so the wheel returns to rigid, leading to a smoother, more stable ride.
By providing on-demand suspension, SoftWheels reduce the amount of vibrations that are transmitted to the body of a rider. The design also enables riders to maintain their forward momentum, which can help reduce fatigue after a long day of riding in a wheelchair.
Statistics provided by SoftWheel report that the product absorbs 50 percent more of initial impact compared to standard premium wheels. SoftWheels are also up to 25 percent more energy efficient than standard wheels, can absorb 2.5 times the force per millimeter of travel, and react and recover twice as fast as any conventional suspension.
Motion Plastics Control the Hub
One of the key components to SoftWheel hubs that help them achieve superior shock absorption are plastic bushings manufactured by igus, based in Germany with a presence in Providence, R.I. SoftWheels include igus’ L280 bushings, which provide superior wear resistance in harsh environments or when used with rough shafts. The bushing, called “The Marathon Runner,” is frequently used when low coefficients of dynamic friction and wear resistance are essential. The bushing also has a high service life.
The bushing's compressive strength of 8,847 psi and tensile strength of 18,130 at 68 °F help the SoftWheels provide their signature stability. igus bushings also require no lubrication and require low maintenance. All of igus’ products are extensively tested, and data reliably predicts the service life of the bushings.
“Using slide bearings based on a nonmetal material has many advantages,” Satz says. “Engineers tried several types of bushings and decided to proceed with igus since it provided the best solution.”
The wheels come with aluminum and magnesium rims in 24-or 25-in. sizes. They have a load limit of 300 lb, weigh about 4 lb, and costs start at nearly $2,000 for a pair.
A Life-Changing Development
Allaina Humphreys has been confined to a wheelchair since 1994 when a gymnastics accident left her paralyzed. The Chicago mother of three had been searching several years for a solution to alleviate the pain nearly every time she went places in her wheelchair. “It was horrendous,” Humphreys says. “I was taking four Advil every four hours and it wasn't touching the pain. Nobody could find anything wrong, and it was just agony. I would spend days in bed, barely moving around the house.”
She had to tell her children the pain was so severe she couldn't hug them. “It was so hard,” she says. “They understood, but they didn't understand. I was desperate. I needed some way to do more with them.”
Humphreys started a GoFundMe account to purchase the SoftWheels in advance of an upcoming vacation with her family. Within 24 hours, donors gave her enough money to purchase the SoftWheels. Humphreys says she “chased down” Barel on Twitter, and he helped arrange to have the SoftWheels before she left for vacation.
The previous year, she felt distraught because she could not participate in events with her family at City Museum in St. Louis and stayed stationary while her family enjoyed the exhibits. That changed when she visited the museum with the SoftWheels. She was a participant in her family's activities, and not just an observer.
“As soon as we got the SoftWheels, I started going over different types of flooring and threshold bumps,” Humphreys says. “They had been causing me a lot of pain. But I was able to roll over them and didn't notice anything. Outside the front door, there was a drop that was an inch and a half. I could roll right over it. I could go down the sidewalk without worrying about cracks. It was an immediate difference.”
The company hopes to expand its design and is working to develop similar technology that can be used with bicycles. A new wheel for the automotive industry is in the research and development stage, and the company is also considering developing a wheel for airplane landing gears. The technology developed by SoftWheel will continue to transform lives, much like it has for Humphreys and her young family.
“My life is different,” Humphreys says. “I have the freedom to go out and about and try new things. Before I was afraid, because I didn't know if I was going to feel pain. It just allows me to be able to be who I want to be.”
This article was written by Thomas Renner, who is based in Connecticut, and writes frequently for U.S. trade publications on a variety of topics. For more information, Click Here. A video of the technology is available here.