Anthopometry Tutorial SYDE 142 July 12 th, 2004

Question 1 You are a designer for a new line of bicycles. Your company has decided it wants to sell an adjustable bicycle, where the bicycle will fit most people - that is, from the 5th percentile female to the 95th percentile male consumer. (Assume a North American market base). [Picture] (8 marks) Assuming that people must be able to sit on the seat of the bike and have both feet flat on the ground (for safety), what should the range of adjustability be for the bicycle seat? (Assume the rider's legs are straight and give the range of seat height from the ground.) b. (4 marks) Present a brief argument you could make to your boss on how to design a bike that will reach a larger segment of the cycling market. Explain what part of the market you will reach and back up your argument with calculations. (Use the tables in Wickens Page 251)

The difficulty with this question is that the measurement is not directly given in the tables. To get the correct measure you need to use two different measures #6 gives you the standing elbow height (height from waist to ground) #12 gives you the sitting elbow rest height (height from seat to waist) Subtract: #6 - #12 is one method of solution. You must subtract because the body from the waist to the bottom of the “posterior” stays on the seat and does not get extended.

Solution Use: X = M + F * s (Recall X= percentile, M= mean at 50%, s= standard deviation, F = multiplication Factor P 248) Looking up the multiplier for 5th and 95th percentile, F = (+/-) In our case: X=[M+F*s] #6 - [M+F*s] #12 95th pc male = 43.5in (1.8in) -[9.5 in (1.3in)] = 34.8 inches 5th pc female = 40.4in (1.4in)-[9.1 in (1.2in)] = 30.9 inches The range for seat height on the bicycle should be inches. The key to expanding the market is to accommodate the 99th male to 1st pc female. For full marks, repeat the solution for this range.

Question 2 (6 marks) Derek likes to work out with his two friends, Lizzy and Tom. Lizzy is a 5th percentile Japanese woman and Tom is a 95th percentile American male. Lizzy and Tom both like to benchpress weights (which involves lying on their back and lifting the weight straight up. Furthermore they like to “spot” each other, which means cover each other in case the other one needs help with the weight. Can Lizzy spot for Tom and can Tom spot for Lizzy? Use anthropometric data (from the yellow data sheet) to justify your answer. Assume the spotter is always standing.

“Spotter” Weight lifter

Solution Need arm length + height measures for Lizzy & Tom (available at measure5 pcf (in cm)95 pcm (in Cm) 67 (Thumb-tip reach) (shoulder height)

Case 1: Lizzy spots Tom Case 2: Tom spots Lizzy Lizzy’s reach = 138cm cm=72.8 cm which is < 88.2 cm so Lizzy can spot Tom Tom’s reach = cm – 88.2cm=69.1 cm which is 65.2 cm so Tom can’t reach Lizzy without bending so he can’t spot for Lizzy

Question #3 A standard chair in a lecture hall is designed for a 50th percentile American male. (1 mark) Determine the seat height from the floor of a chair designed for a 50th percentile American male. (2 marks) Determine whether or not a 5th percentile Japanese female can place her feet flat on the floor. If not, how many centimetres away is she from the floor? (3 marks) Determine what angle the 95th percentile male must adopt at the knee in order to place his feet flat on the floor without lifting his knees above the seat pan. (You can assume they open up their ankle angle appropriately to put their feet on floor.)

Solution a) The best solution is based on using popliteal height (measure 678 in the tables). Href=44.4cm Seat height would be designed to be 44.4cm (1 mark)

Solution b) H (female Japanese 5 pc) =34.7 cm (Measure 678) –H (American Male 50pc) -H (Japanese Female 5pc) = The Japanese female’s feet would be 9.7cm away from the floor (2 marks)

Solution c) H (male American 95pc) =48.1 cm (Measure 678) For this part, simply setting it up based on the different popliteal heights is fine (see the figure below). –Cos(theta)=44.7/48.2 –Theta=arcos(44.7/48.2) –Theta = 22 degrees The 95th percentile male must angle his legs at 22 degrees to sit in the chair. (3 marks, 1 for the measure, one for the setup of the problem, and 1 for the correct solution)