A low cost self-assemble bicycle for students

Abstract

The graduation assignment is defined as follows: design a low cost bicycle for both male and female students in The Netherlands. Investigate what factors can decrease the costs by researching the entire supply chain and material costs. Determine which parts need to be redesigned and which parts will remain standard. Investigate what the possibilities are for self-assembling. The bicycle should be stripped from all the components which are not essential for cycling. The user should be able to assemble the bicycle by him- or herself with the use of basic tools which are present in an average household. The project started with an analysis phase. A market, user, product and literature research resulted into a list of requirements. The most important requirements are: the usual dealer margin must be eliminated by using a webshop (1), the assembling costs usually take up 25% of the total price, this must be reduced by letting the user assemble the product (2), the bicycle must have a selling price under €100,- (3), the bracket axle, steering head and wheels need to be pre-assembled (4), the frame needs to be redesigned will maintaining enough strength and stiffness(5), the tariff duty on transport costs need to be decreased by transporting the product into loose parts, the assembling of the bicycle may not take longer than 90 minutes and needs to be finished in less than 25 actions. After the analysis phase the idea generation started. An individual brainstorm as well as a group brainwriting session have been conducted to generate ideas. This resulted in three different concepts, which are all based on a redesign of the frame that can be self-assembled by the user. The first concept is based on a sheet metal frame produced by pressing it into shape. The second concept is based on a frame which uses a constant extrusion profile and is connected by simplistic sheet material parts which are lasercut. The third concept is based on a frame made out of sheet material produced by stamping creating a “truss-like” structure. Based on the weighted criteria method, the second concept was chosen to develop further in the embodiment design phase. The detailing of the concept involved researching the production process of aluminum extrusion for the frame elements and lasercutting for the connection pieces. A complete CAD model has been developed for simulating extreme user scenarios to validate the strength and stiffness of the design. This resulted in several innovative solutions for the bracket axle, front fork and seat adjustment. The design is called “ALEX”” derived from the production process being aluminum extrusion. ALEX is designed so that it can be assembled with a Wrench 10 and an Allen key 5. Also a analysis of the aesthetics, packaging and transport has been done. All these analyses were used as an input for a detailed cost estimation. The estimated selling price is €85. A full scale prototype has been developed to validate the self-assembling features of the design. A user-test with four persons has been conducted in order to investigate if they could assemble ALEX by themselves with the help of a provided manual. Some recommendations are given and the entire project is concluded and evaluated in the last section with the list of requirements. ALEX has four unique selling points: it is low cost, able to be self-assembled by the user, has an innovative design and can be delivered right on the doorstep in a box as big as a 28” wheel.