Recently I have experienced some neural oscillations about sizing chairs based on the users body dimensions. I recall reading an article, a few years ago, by Jim Tolpin in which he stated; "The human frame can be roughly proportioned in whole-number ratios of eight". The theory is this; By dividing the distance of ones hand span into eighths (8:8 ratio), you will then be able determine any dimension needed to design furniture to fit the user. This led me to do a little research on Leonardo Da Vinci's Vitruvian Man and the proportions of the human form. From this information one can derive that we are as tall as we are wide with outstretched arms. Which by the way is equal to eight hand spans (64:8). Our shoulder span is equal to two hand spans (16:8), our forearm (wrist to inside of elbow) is equal to one hand span (8:8), and the length of the lower leg (floor to middle of the knee) is a ratio of 18:8. I know what you are thinking. Very few people fall into the Vitruvian Man "ideal" category. This is true and most of these proportions will not be exact but should be close enough to use in the design of a chair or any furniture for that matter.
Well, I had to put what I had learned to the test. I got in touch with my good friend Dean and asked him to measure his hand span. Yeah I didn't really think it through or look at the time before I initiated the conversation! After a few questions about my activities that evening, he reluctantly took the measurement and advised me that the measurement was 8.75 inches. I then asked him if the span of his shoulders was 17.5 inches. This is when he accused me of drinking to excess and politely cut the conversation short. Knowing Dean as I do, I knew this would eat at him until he would take the measurement to satisfy his curiosity. I also knew that I would soon hear from Dean. As suspected, he did take the measurement and confirmed my calculation, and was still of the opinion that I was drunk.
It is my hope that I will be able to use these whole-number proportions and the clients hand span dimension to design a chair that will fit the client for its intended task. I especially want to employee this method with my guitar chair that is still in the designing/prototype stages. Over the next several months I will be building and testing some prototypes using only this method. If this proves to be successful, imagine how easy it would be to custom build a specialized chair for someone on the other side of the country.
I would deduce that the chair below belongs to someone with rather big hands, and you know what "they" say about big hands. Big Chair?