ATP Series

Seat Slope: A Personal Perspective

Doug Garven knows a lot about seat slope.

For one thing, his education and background are in industrial design, and his body of work in creating highly functional, highly attractive ultralightweight manual chair is well admired.

But he’s also a consumer who knows that the many dozens of individual measurements and specifications for that ultralight chair are more than just a list of numbers on an order form. They impact such critical factors as propulsion efficiency and posture, and can ultimately determine how comfortable, safe and functional the consumer is.

We asked Garven, a member of TiLite’s industrial design team in the manufacturer’s engineering group, about his personal experiences with seat slope.

On finding the “right” seat slope: “Like everything with wheelchairs, it’s a compromise. You do one thing, and it solves the problem, but it creates another, and it’s always trying to find that sweet spot that gives the best of both worlds. It’s different for every single user because of what their abilities are, what their injury level is, what their wheelchair skills are. All that plays into effect.”

On the seat slope he personally prefers today: “I sit at a 2" difference from front to rear. And that is kind of an industry standard. If you take a sampling of chairs, most of them fall into that range. That’s for your average para.”

When typical seat slopes vary: “I’ve sat in a deeper seat-dump chair. Sports chairs will all have that because of the added stability it creates. But there’s your trade-off again, too. If somebody’s at a real low injury level, they can sit a lot taller and straighter, and it gives them improved eyesight and better interaction with ablebodied people, but you have the tradeoff of losing good propulsion on your wheels if you sit too tall. Typically, it’s a rule of thumb that when you drop your hands down by your side with your fingers extended, you would like the fingertips to be at the center of the wheel. That gives you the most range on your push stroke.

“In a sport application, you’d want to sit even lower and get that extra stability, but for every day that doesn’t become practical for the things that we were mentioning. It’s harder to transfer out of, and it’s easy to get under tables, but you’re so low to the ground that you lose the ability, I think, to communicate with people. You almost make them feel obligated to kneel down when they talk to you.

“Ten to 15 years ago, when your everyday chair was your sports chair, (seat slope) was an adjustment they would do a lot. But the sport chairs have all evolved into their own specific chairs, as has your everyday chair.”

This article originally appeared in the August 2012 issue of Mobility Management.

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