Leisure bicycles are fabricated in a variety of ways these days. Although, the bicycles are designed and manufactured in a variety of ways by numerous companies, customer has a difficulty in gaining information of bicycle which suits them. Accordingly most of buyers purchase bicycle considering body size. Employing the method is one of the ways to decide bike size on the ground of standard body measurement. However, the method above to purchase bicycle is not appropriate for customer considering his/her body. The research mainly aims to design bicycle which allows buyer to adjust optimal design system by himself/herself considering his/her body size. In addition, a device employing fuzzy controller implemented bicycle run test. Using on the result, the research explored an optimal bicycle system which makes a decision whether a bicycle fits body of customer.