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Form & Function

Reprinted from SNS May 2017

Adaptive athletes demand a lot from their wheelchairs, and manufacturers are using lighter and stronger materials to meet those needs

For anyone who plays a wheelchair sport, a specialized wheelchair plays a major role in the game. Athletes spend a great deal of time learning how to maneuver their chairs to gain an advantage over their opponents.

But have you ever thought about the work that went into making that wheelchair? As adaptive sports continue to gain recognition and more programs start up around the country, the manufacturers of sports wheelchairs also continue to grow and evolve to keep up with athletes’ demands. 

With strong, lightweight materials tailored to an individual athlete’s needs, the sports wheelchairs made today are built to complement every style of play and ability level. 

How They’re Made

The first step in the athlete’s process is to get evaluated and measured, including his or her height, weight, leg length and hip width. From there, the sky’s the limit with countless customizable options that best suit the athlete’s comfort, range of motion, style and pocketbook. With such a wide variety of companies to choose from, athletes should schedule a talk and fitting with an expert in the field, their coach or a representative from their chosen wheelchair manufacturer about their specific needs and desires.

At Invacare Top End, for instance, once a shop order has been placed for a racing wheelchair, it goes out to the fabrication department. The fabrication department constructs all of the tubes used in building the racer. The tubes are delivered to a welder, who welds the main frame and cage, including the fender, head tube and camber tube. Then, it goes into the sheet metal area to be fitted with a kneeling pan if one is required, and sideguards, and then it’s sent through the paint process. It’s then taken to upholstery, where it receives the back and seat upholstery, as well as any strapping that’s necessary for that chair. Finally, it’s taken to assembly, where the fork, front wheel, rear wheels, steering component and track compensator are all assembled onto the chair. 

Paul Schulte, a senior engineer at Invacare Top End, says the average time to build a chair is seven to 10 days, but the timetable depends on the workload at the shop, as each chair is made to order and assembled by hand, one at a time. The maximum time is four to five weeks.

The process is similar at Per4Max, where athletes go through a 20- to 30-minute evaluation to find the best setup for their classification and position on the basketball court. 

Per4Max basketball wheelchairs start out as lengths of round tubing on a materials rack. 

“We cut everything to length, we bend it, we notch it and we jig everything up in our jigs that are adaptable to whatever the measurements for the end user are,” says Chris Kommer, Per4Max chief financial officer. “So there’s no two chairs for us that are the same. We tailor that chair to specifically what they need. When it comes to colors, when it comes to different adaptations for different athletes, whether their disability is an amputee or paraplegic or CP [cerebral palsy], we can make a setup that’s going to complement whatever their limitations are so they 
can compete at their absolute highest level.”

Kommer says there are three levels of quality control to ensure the dimensions and the toe-in/toe-out are right before the chair is ready for paint.

“We go through a heat-treating process so everything is solidified, no potential for frame failures,” Kommer says. “And we provide factory support for these athletes, specifically at the international level and professional level. Just like any other professional athlete, they require factory support, whether it’s from Nike for their sneakers or whether it’s in motorsports, there’s factory support provided by, say, Honda, Yahama, Suzuki, when it comes to parts, components, adjustments, things these athletes require.”

Because of a backlog of orders, time to delivery is 10-12 weeks, but the actual production process takes about two and a half weeks, Kommer says. Both companies utilize 6000 series and 7000 series aluminum, which is strong, durable and cost-effective. The 7000 series is also about 20% lighter.

Schulte says the elite products in the Top End line use heat-treated 7000 series, and many of their chairs have carbon fiber or composite components in targeted areas, like the backrest and chain guard on the Force RX handcycle. 

“As long as Top End’s been around, we’ve been looking into different or new materials that we can utilize,” Schulte says. “Top End will always be hunting for another type of material, another application where we can utilize modern-age techniques and materials to deliver a better product. Top End has always had a strong tradition with the Paralympics. One of the other things that fuels the ideas is the Paralympics itself, so looking at how do we go faster, how do we help make the athlete even more agile, how do we help compensate for that person’s disability?”

Likewise, Per4Max looks for ways to lighten their chairs using carbon fiber in places where components would normally be aluminum-plated or plastic.

“We’re doing everything from wheels to different tires that hold more air pressure [140-150 pounds per square inch], to lighter components. How about titanium hardware? Everything we can do to shave ounces off while still maintaining that integrity and strength, as well as having a progressive setup that’s going to allow these athletes to go out and do what they weren’t doing before in their old chair,” Kommer says.

There are many types and sizes of wheels, including those with pushrims for racing chairs, handrims for basketball chairs and drive wheels for handcycles that all get added in assembly. 

Each company offers standard wheels and tires that are meant to be durable and get the athlete going. Upgraded wheels can be lighter and more aerodynamic, like a carbon fiber disc wheel or carbon fiber spoke wheel for racing, or stronger and able to take impact for basketball or rugby. 

Spinergy wheels and casters are popular upgrades for basketball chairs but can add $695 to $1,295 onto the cost of the chair. Wheel size and camber are generally specified by the athlete and depend mostly on the athlete’s size, strength and ability level.

In wheelchair racing, Schulte says, a 700c size wheel is used a majority of the time, while 26-inch wheels can be used by young athletes and those with shorter arms. In wheelchair basketball, there are four wheel sizes — 24, 25, 26 and 700c. If athletes want to sit tall, they have a larger wheel so they don’t have to reach too far. 

Per4Max has many different options of upholstery, from air mesh and solid cushions to pressure-relieving cushions, as well as tension-relieving backrest options. Top End provides standard cushions, no gel or memory foam, but there are other cushions available within Invacare, such as the Matrx line. 

“It’s not uncommon for an athlete to get an after-market cushion from a third-party distributor,” Schulte says. “Our recommendation to athletes is any issues with skin can be an athlete’s worst nightmare, so ultimately, athletes should take care when choosing their cushion. Speak with a health care professional. Sometimes people are surprised at how much of a different position you can get simply by adjusting the upholstery correctly.”


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