## 1 Introduction
TOPSIS introduces two reference points: positive ideal and negative ideal, enabling quick identification of the best alternative [11]. However, it does not consider the relative importance of distances and depends on the evaluation unit of the criterion function for normalized values. VIKOR is a useful tool in a multi-objective environment [11], providing scientifically and reasonably sound results for decision-makers. It is particularly powerful when decision-makers are unable to express their preferences at the beginning of the problem design. VIKOR allows for conflicting criteria with different units and involves analysing stability intervals to determine weights. However, VIKOR's results depend on the ideal solution, and including or excluding an alternative can impact the ranking of a new set of alternatives. The derivation of preference rankings in VIKOR has also been subject to improvement proposals. Considering the specific objectives and requirements of the research paper, the AHP and QFD techniques were found to align effectively with the design process for the mechanical energy storage device applicable to bicycles. These techniques provide the necessary structure and methodology for evaluating and prioritizing criteria and alternatives in a manner that complements the design approach and goals. The Analytic Hierarchy Process (AHP) is a decision-making tool [12] that allows for analysing and comparing different options based on a set of criteria. This technique is often used in product design to help identify the most important criteria and to evaluate how well different design alternatives meet those criteria [13]. Due to its ability to structure complex problems into hierarchies and facilitate systematic comparison and evaluation of criteria and alternatives, by breaking down a problem into levels and sublevels, AHP enables decision-makers to carefully analyse and weigh different factors and considerations. This is especially useful in situations where criteria and alternatives are numerous, and a clear understanding of their relationships is needed. The hierarchical structure of AHP provides a coherent framework for addressing complex problems and helps decision-makers better grasp the impact of their choices across different levels and aspects. However, it is important to note that AHP has some limitations in addressing complex problems. While it can handle both subjective and objective criteria, its focus on pair-wise comparisons and assigning numerical values to subjective preferences may fall short in certain cases. Additionally, the hierarchical structure of AHP may not fully reflect the relationships and opinions in complex projects involving multiple levels, horizontal links, correlations, and feedback. While AHP has been successfully applied in various contexts such as project management, corporate decision-making, and personnel selection, there are criticisms suggesting it may not be suitable for complex problems. These criticisms argue that AHP oversimplifies the decision-making process and fails to address the broader implications that decisions may have on the lives of many people. In summary, AHP is a valuable tool in decision-making by providing a hierarchical structure and systematic methodology to address complex problems. However, it is important to recognize its limitations [14] in handling subjective criteria, interrelationships, and accurately representing the complexity of certain problems. When evaluating the suitability of AHP for a particular problem, careful consideration of the specific characteristics and demands of the problem, and if necessary, complementing the AHP approach with other more suitable decision-making tools or methods, is crucial. QFD is a process that helps to ensure that the final product design meets customer needs and expectations [15]. This technique involves identifying the customer's needs and translating them into design requirements.