Ergonomic product design considering both anthropometric variability and user preference is required for harmonizing the target users and products. In this study, bicycle handle diameters for three size categories were determined by considering anthropometric variability and preference. To design the bicycle handles, a four-step process was applied: (1) define anthropometric data, (2) develop size chart, (3) define a design equation, and (4) determine design values. In the first step, the 1988 US Army data was chosen as anthropometric data for the design target population. In the second step, to develop a size chart of bicycle handle, hand length and circumference were selected as key dimensions by principal component analysis on six representative hand dimensions. Next, a size chart of three categories (small: 175.5 mm, medium: 186.7 mm, and large: 196.2 mm) were derived by K-means clustering analysis for hand length and circumference. In the third step, the design equation accounting geometrical relationship between the sizes of two key dimensions and diameters of bicycle handle was adopted from a relevant existing research. In the last step, design values (40.9 mm, 43.5mm, and 45.7 mm) for each size category were calculated by inputting the sizes of the key dimensions to the design equation. To evaluate user satisfaction level of the bicycle handles, a user testing of three handle prototypes was conducted for 17 participants with various hand sizes. The test results showed that satisfaction scores for each hand group were significantly higher at the corresponding size category.

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In this study, optimal grip span between a bicycle handlebar and a brake lever was determined by a twodimensional biomechanical hand model. A three-step process was applied: (1) develop a two-dimensional biomechanical hand model, (2) determine input data for hand model simulation, and (3) conduct mathematical simulation. In the first step, in order to estimate tendon forces, joint constraint forces and total gripping support force at the metacarpal, a mathematical static hand model was developed based upon the hand anatomy and static equilibrium conditions. In the second step, US 50%ile hand length was selected as target population from the 1988 US Army data, and grip postures for five participants(average hand length = 18.2 cm and SD = 0.8) were measured to get joint angles( 1

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