I’m often asked about the high amount of camber for my wheels on my wheelchair. About time I explained it in one place so I can refer people :)
What is "camber"?
Camber is the word we use to describe the angle of a wheel in relation to the wheelchair frame. If there is no camber (0°) the wheels are perfectly vertical in relation to the ground. If there is a lot of camber (15°) the wheels the wheels will be very far apart from one another where they meet the ground, and closer to one another at the top.
You generally see wheelchairs with a strong camber on sports wheelchairs. And… Camber isn’t camembert :) Errr, silly joke.
My wheelchair is not a sports chair.
So many people approach me and ask if my chair is a wheelchair rugby chair, or a sports chair. Because it looks different than a lot of the wheelchairs out there. And because of the camber, I think. My wheelchair is most definitely not a sports chair. It is a nice every day chair. To use an analogy many people might understand – if my wheelchair were a car, it wouldn’t be a Ford Escort, more like a Porsche.
So, why so much camber?
I have about 10° of camber on my wheelchair. I told the guy who build it (no longer in business, unfortunately) to give me as much camber as possible while making sure I still fit through most doors. So that’s what he did. My seat width is 15" at the back 13" at the front. He ran his calculations and came up with about 10°, on 26" wheels. This is not adjustable. The chair is custom build and there is no adjustment to be had here. I took a punt that it would be right, and it is. Had the chair 8 years now and it is still good, and fits me.
The more camber one has, the easier it is to spin within a small radius. That’s why rugby or basketball chairs often have a lot of camber. So I chose camber to be better able to turn around and change direction quickly. This is handy, for example, when a distracted mother pushing a shopping cart full of groceries comes out of an aisle without having seen me, I can veer out of the way and avoid collision (this happened as recently as a few days ago!)
With a wider wheel-base, I am more stable on side-to-side motions. I don’t tip sideways as easily as I otherwise could. This one is important coupled with manoeuverability – if I go around a corner as a good speed, I have no fear of my wheelchair going airborne on one side.
Easier to push
Those of you walking may not really notice it, but sidewalks *always* have a gradient. That is, the ground is higher near the building and lower near the street. This angle is necessary to allow for water drainage. You don’t need a very steep angle for water to find its way to the gutter. A 2% angle, or a ratio of 1:50 is sufficient – that is you would be going up 1 meter for every 50 meters of travel. You’d barely notice the incline, but the water would. A wheelchair user *would* notice it, but it would not be an issue. Many sidewalks have a cross-slope of 1:20, even higher.
People trying my spare wheelchair tell me they think it is "broken", because they have to work so much harder at pushing on one side, and almost need to break on the other side. You see, the chair has a natural tendency to aim to the gutter, it wants to go downhill. So you have to push hard on the rim nearer the street, and hold back on the wheel nearer the building.
A wider wheelbase makes that somewhat more easy to handle.
Gets people asking about the chair. Seriously. It’s an advantage. I often have to repeat myself, but I’ve gained the attention of many a g33k or boy-racer with my wheel setup. People stop seeing the wheelchair as an object of pity, as a limitation factor, and start seeing it as the interesting piece of engineering that it is.