Wheelchair Riders in Control

Wheelchair Riders in Control
WWI’s Model of Technology Transfer
by Peter Pfaelzer, Ph.D. and Marc Krizack, J.D.

This article describes Whirlwind’s design methodology from its beginnings in 1980 until 2005, when
Whirlwind focused on small shop manufacturing. Today we call this design methodology “User- Originated.” Although Whirlwind now designs for larger scale manufacturing with a significant amount of work done on the computer, much of this article retains its relevance for those interested in good, appropriate design for people in the developing world.  (article .pdf here)

When Ralf Hotchkiss began designing wheelchairs in Latin America in 1980, there was no one else designing state of the art wheelchairs at a low cost for active use in developing countries. Today, there are at least four other non-profit organizations promoting wheelchair production around the world. Yet Hotchkiss’s model, since expanded and now institutionalized at Whirlwind Wheelchair International, remains unique in its approach. For unlike other organizations, WWI ascribes to the wheelchair rider — as designer, trainer, mechanic, tester, and even marketer — the central role in the technology transfer
process. This model has made the Whirlwind Network of independent wheelchair producers the highly productive source of new ideas in wheelchair design that it is today.

Design Methodology
The most common design methodology used in modern manufacturing today is the prescriptive design process. This methodology is characterized by a multi-step linear process of problem formulation, idea generation, and prototype production. It presumes that most significant relevant information and resulting solutions can be learned prior to production, and it relies on highly educated experts in every stage of a centralized design process. The prescriptive process is employed to minimize the risk before large amounts of capital are invested in the production of costly prototypes. The process itself requires the expenditure of significant amounts of capital.

 Problem, Protype, Evaluations, Solution


Prescriptive Design: The time and money spent on problem formulation and ideation prior to prototype construction may reduce the number of prototypes necessary to produce a successful design. WWI’s design methodology is based on a method more common in small business known as the descriptive design process. This process was the primary design process utilized prior to the turn of the century when engineers learned their craft on the shop floor rather than at specialized technical colleges and universities. In contrast to the modern engineering prescriptive design process which requires a substantial amount of early work on paper or the computer, the descriptive process is characterized by the early production of a prototype. The design is refined through repeated prototype/evaluation/prototype cycles. The designer learns about the problem through the generation and evaluation of sequential prototypes.



The descriptive process relies to a large extent on the craftsperson in a more decentralized design process and may require more prototyping cycles than the prescriptive method. However, for a product like a wheelchair, that can be prototyped quickly and inexpensively, the descriptive design process is efficient and cost-effective. For WWI, use of the descriptive design process derives naturally from the socio-economic situation in developing countries and from the complex nature of disability itself. Unlike general product design, which is aimed at the population at large who within a certain range can all be accommodated by a single design, product design for people with disabilities is difficult because it requires multiple solutions. A wheelchair is not merely a chair with wheels. Different wheelchair riders, even with the same nominal disability such as paraplegia, quadriplegia, multiple sclerosis, cerebral palsy, or post polio, can have widely different ways of sitting and pushing which need to be considered in the design process. The mobility equipment needs of disabled kids also change as they grow. One only has to look at the wide range of wheelchairs available in industrialized countries to understand fully how complex designing for disabilities really is.

What Difference Does the Setting Make?
    The design problem is made even more complex for designers of mobility equipment in the developing world. As a matter of course, wheelchair design must also include consideration of diverse uses and geographical conditions. Wheelchairs can be for indoor use, outdoor use, long distance travel, urban use, rural use, and quite often must function well in dirt, in mud, in fields, on gravel, through bomb craters, etc.
WWI’s wide rubber caster, known as the “Zimbabwe Wheel,” is the result of design for the most rugged conditions.
The absence of even the most basic accessibility in the architectural infrastructure and public transportation must be considered in the design process. As an example, the extremely narrow bathroom and elevator doors in Russia gave rise to the Siberian wheelchair frame which can be narrowed by the rider while sitting in the chair. Cultural factors can also affect wheelchair design. In many countries in the Near East and Asia, for instance, much social activity, including cooking and eating, occurs at floor level. Wheelchairs in these
settings must be designed to allow the rider to participate in these activities. The newest Whirlwind allows some users to sit near the floor by incorporating a jump seat at the level of the footrests.

Wheelchair design must also take into consideration such factors as the type of toilet facilities available, which can often be little more than a hole in the ground or floor. The wheelchair rider/builders in the Whirlwind Network wish to achieve the greatest degree of independence, mobility, and social integration possible. Thus, their wheelchair designs must be capable of responding to these multiple needs. The prescriptive design methodology, working as it does at some distance from the wheelchair riders in developing countries, is unlikely to produce the range of solutions necessary to answer these local needs.
Wheelchair design in developing countries is also limited by cost considerations. Because most people who need a wheelchair cannot afford an imported one, low price is a primary design criterion. The two main ways of keeping wheelchair prices low are through low initial capitalization of wheelchair shops and by the use of materials readily available where the wheelchair is to be built.
All plant and equipment costs must be amortized and included in a wheelchair’s retail price. When initial capital funds are borrowed, the cost of repaying the loan must be included in the chair price as well. Low per shop capitalization costs make it easier to raise start-up capital and establish more production facilities. These multiple producers can form a competitive marketplace for wheelchairs keeping quality high while forcing prices down. At the same time these producers can act cooperatively, each becoming part of a design network. This is how the Whirlwind Network came to be.
The use of readily available materials is necessary to keep costs low and ensure that the chair will be locally repairable. For Third World wheelchair design this often means that a single model will have multiple design variations.
Even within a single country, political and economic factors can either limit the availability of existing materials or create a situation where previously costly materials become available and affordable. The placing or lifting of trade barriers to the importation of bearings, for example, has had a big impact on the design of wheelchairs. In Africa where bearings were too expensive, WWI designed roller bearings using steel nails or welding rod. In 1983 in Nicaragua, the price of acetylene used in welding skyrocketed as a consequence of the Reagan administration’s economic embargo. Wheelchair rider Omar Talavera
responded by designing a caster fork made from a single piece of bent steel rod that did not need to be welded. Although only meant as a temporary innovation, it nonetheless kept the price of caster forks affordable until the embargo ended and the cost of acetylene dropped. The lesson is that wheelchair designers must be capable of producing rapid solutions as the local availability of component materials changes.

Wheelchair Riders Integral to Design Solutions
Historically, these many needs have been best understood and dealt with by wheelchair riders involved in every aspect of a continually evolving design and production process. WWI at San Francisco State University nurtures this process by acting as the hub of a network of wheelchair builders now spanning more than 25 countries. WWI’s role is to energize and extend the network, promote and coordinate activity, serve as the communications center, and stimulate and cross-fertilize the design process. The WWI design teams have always included at least one wheelchair rider. Our wheelchair rider-designers use the chairs they design during their daily activities to understand exactly how they perform in real
Both at San Francisco State University and around the world, WWI wheelchair building courses always include a significant number of wheelchair riders among the training participants. These participants become active collaborators in the design process. They ensure that WWI is kept aware of all the factors which affect their real mobility needs and often provide the design answers themselves. We term this process “Collaborative Design.”

Phillipe Mazard (Handicap International, France) discusses marketing schemes with David Mukwasa from Disacare (Zambia).

Although theoretically there is no reason why wheelchairs can’t be built exclusively by non-disabled designer/mechanics relying on information supplied by wheelchair riders, the reality is that very few non disabled persons fully believe and understand what people with disabilities say, even about matters which a disabled person can be expected to know most.
Wheelchair designs, once translated into prototypes, must be tested. WWI uses inexpensive shop floor strength tests and obstacle course performance tests to simulate real conditions. But the only way wheelchairs can be tested under the full variety of actual conditions and for every conceivable purpose is by wheelchair riders who use the chairs every day. Over time wheelchair riders provide the feedback which is essential for going to the next level in the design process. They have the added benefit of a good wheelchair during this evaluation process, and unlike the evaluation process in the prescriptive design method, the cost of testing and evaluation is minimal and design changes can be made rapidly.
The involvement of wheelchair riders in wheelchair design and production also affects the technology used in wheelchair building. Many of the wheelchair riders we train have only basic mechanical experience and little formal schooling. Production methods and training techniques must be kept simple to facilitate the training process. The practical strength tests and obstacle courses, along with the use of full-size drawings, pictures, and similar techniques facilitate the participation of people who by and large are without formal advanced educations. We have sometimes learned this the hard way. Ten years ago WWI abandoned a nicely compact footrest design whose compound angles were so difficult to bend properly that even the trainers wasted a lot of time and tubing trying to get it right.

Marketing Advocates
A critical area in which wheelchair riders can play a decisive role is wheelchair marketing. Because most wheelchairs in developing countries are purchased by government and private charities rather than the end user, the wheelchair rider/consumer has not had the ability to influence quality and price to the same extent as purchasers of general consumer products. But wheelchair riders can play an effective role in gaining increased government funding for good quality, locally built wheelchairs. In Novosibirsk, Russia, activists from the Finist (Phoenix) Disabled Sports Club demonstrated the Whirlwind wheelchair made in
Novosibirsk to government officials in charge of wheelchair purchases. They made these officials realize that wheelchair riders are the real experts when it comes to wheelchairs, and they educated the officials about the Whirlwind’s advantages for active use. That effort led to a government order for 500 Whirlwind wheelchairs.
Wheelchair rider/advocates also play an important long term role in developing the wheelchair market. The removal of architectural barriers and the increase in accessible transportation open up new opportunities, especially for people with more significant disabilities. This will create a need for improved wheelchairs so that, to paraphrase Star Trek, they may go where no wheelchair rider has gone before.

The most efficient use of development funds for promoting the design and production of wheelchairs in developing countries is through a decentralized international network of small to medium sized production shops, coordinated through a central hub which facilitates communication and collaborative design through newsletters, wheelchair design congresses, technical exchange visits, web pages, and other means. Most importantly, because someone has to be responsible for making the difficult choices involved in balancing design features against cost, the wheelchair rider, who knows the problems best and is most affected by the prescribed solutions, must play the leading role in wheelchair design.

The authors wish to thank Joan Rogin for her contributions in both the conceptual and editorial phases of this article.

Customizing and Ordering My Roughrider

Seat Width

To find the distance between your hips, first position yourself seated with pelvis upright on a firm surface. Then, measure the distance between the widest points of the hips and thighs without compressing any tissue. Finally, record your measurements. It is important not to have a chair that is wider than necessary as it will be harder to push and may prevent you from passing through narrow doorways.

Seat Depth

Position yourself seated upright on a firm surface. Measure the length of your upper leg, the distance from behind the knee to the back of the pelvis (back of your lower leg). Subtract 1/2” to find the maximum seat depth, to allow for space between the back of the knee/upper leg and seat fabric. Record the final measurement.

Backrest Height

Your preferred backrest height is determined by your personal comfort level and physical ability. Whirlwind recommends, generally, that the top of the back support should fall just beneath the bottom of the shoulder blade. For less active riders who require more torso support, the back support should be higher, falling just beneath the armpit. Position yourself seated upright on a firm surface. Hold your hands flat against the surface you are sitting on. Measure the distance from the seated surface to the desired, most comfortable point for support on your back. To this number add the height of your cushion when you are sitting on it. Record the measurement.

Preferred Backrest Angle

Backrest angles are determined by the torso control of the rider. Whirlwind recommends that those with less torso control, such as quadriplegics, sit with a backrest angled further backwards to avoid falling forward in a wheelchair. Those with more torso control, such as amputees, can sit with the backrest more upright. Proper backrest angle is best determined by an occupational therapist or healthcare professional. Although there is only one option – 8 degrees – in the drop-down list below, you can adjust the backrest angle by adjusting the backrest straps (i.e. looser at the bottom and tighter at the top for a more erect position).

Now please enter your measurements into the fields on the product page before ordering. For more information about measuring, please refer to the RoughRider Fitting Sheet. You are responsible for choosing the right chair for yourself. If you are uncomfortable with determining your wheelchair size, please consult a professional.