Project-Based Learning (PBL) is an effective pedagogical approach to developing critical thinking skills, problem-solving skills, and collaboration ( Hughes & Afrin, 2024; Razali et al., 2024). This learning model provides an authentic learning experience by connecting theory and practice in a real way ( Carvalho et al., 2024; Kumar & Sajjan, 2024). Compared with traditional learning methods, PBL has been proven to be more capable of developing higher-order thinking skills, while increasing learning motivation ( Pamungkas et al., 2025; Yao, 2025). In addition, the application of technology in PBL provides significant added value because it can enrich students’ learning experiences and expand the learning context in a more innovative direction ( Cima et al., 2025).

As it evolves, PBL is increasingly enriched with various technologies, from robotics and the Internet of Things (IoT) to renewable energy. This technological integration provides students with the opportunity to hone their professional competencies by completing authentic assignments that mimic real-world challenges ( Kraśniewski, 2025; Tsai, 2024). However, the implementation of technology-based PBL also faces various obstacles, such as limited laboratory facilities, high costs, and unequal access to resources between educational institutions ( Amador Nelke et al., 2024; Habibi et al., 2025). At secondary and vocational education levels, although it has been proven effective in improving students’ conceptual understanding and analytical skills, the implementation of PBL is still hampered by the rigidity of the curriculum and the limited readiness of educators.

The increasing global attention to sustainability issues positions PBL as a relevant approach to integrating social, economic, and environmental dimensions into the learning experience ( Espino-Díaz et al., 2025; Guerra et al., 2025). Through project-based learning design, students not only build academic competencies, but also critical awareness of the sustainable development agenda ( Caprari et al., 2024; Guerra et al., 2025). PBL in this case functions not only as a pedagogical strategy, but also as a vehicle for social transformation that bridges educational interests with the real needs of society and global challenges.

Electric bicycle conversion emerged as a unique PBL medium because it combined technical skills with an awareness of the importance of sustainability. This project required students to master design and engineering aspects while internalizing the values ​​of a green energy transition ( Huang, 2022; Mani, 2024). At the higher education level, the implementation of electric bicycle conversion has been proven to increase learning motivation, technical skills, and entrepreneurial orientation ( Lin, 2022). Meanwhile, in secondary education, mobility-based experimental activities can strengthen critical thinking skills and conceptual understanding ( Lin, 2022). In a community context, this initiative even contributes to social inclusivity, intergenerational solidarity, and local economic impact. However, the existing literature remains fragmented and relatively limited, necessitating a systematic review to map trends, learning outcomes, challenges, and future opportunities from implementing electric bicycle conversion as a PBL medium.

This systematic literature review aims to identify motivational trends and uncover gaps within the existing body of research. Accordingly, the study seeks to address the following questions.

Data collection for this study was conducted through two reputable international databases: Scopus and Web of Science (WoS). These two databases were chosen because they offer extensive coverage of scientific literature and strict article selection standards, ensuring the quality and credibility of the publications analyzed ( Albuquerque & Gomes dos Santos, 2024; Bristi et al., 2025; Zhao & Selvaratnam, 2024). The search was conducted on June 30, 2025, with a publication period of January 2020 to June 2025, in line with the increasing global attention to sustainability-based pedagogical innovations over the past five years. The search strategy was formulated using three main strings linking the topic of electric bicycle conversion to the Project-Based Learning (PBL) framework and STEM education, as summarized in Table 1.

The initial search yielded 1,268 articles (923 from Scopus and 345 from WoS). After removing 240 duplicates, 1,028 articles were screened based on title and abstract. At this stage, 742 articles were eliminated because they did not meet the topic criteria (not related to PBL, not focused on electric bicycle conversion, or only discussing technical aspects). This left 286 articles submitted for full review. Of these 286 articles, 20 were inaccessible. Furthermore, 266 articles were successfully reviewed in full. After the eligibility assessment process, 245 articles were eliminated because they did not meet the inclusion criteria, resulting in 21 articles being deemed eligible for further analysis. To clarify the selection procedure, the inclusion and exclusion criteria shown in Table 2 were used.

The entire process of identification, screening, and assessment of article eligibility follows the PRISMA 2020 protocol ( Albuquerque & Gomes dos Santos, 2024; Fitriyah et al., 2025; Zhao & Selvaratnam, 2024) to ensure transparency and replication. The PRISMA flowchart ( Figure 1) details the selection steps taken to obtain the final 21 articles for analysis.

Article selection is carried out by following the PRISMA 2020 guidelines to ensure transparency and traceability of the review process ( Gao et al., 2024; Wang, 2021; Widowati & Tyas, 2024). An initial search of the Scopus and Web of Science databases yielded 1,268 articles, which after deduplication was reduced to 1,028. A screening phase based on titles and abstracts eliminated 742 articles for being irrelevant to Project-Based Learning (PBL) or electric bicycle conversion, and for being purely technical in nature without an educational dimension. A total of 286 articles were then reviewed in full text. Of these, 20 were inaccessible, while 245 were eliminated for not meeting eligibility criteria, including insufficient focus on PBL or lack of educational implications. Ultimately, 21 articles were deemed eligible and included in the final analysis. This selection process is visualized in the PRISMA diagram in Figure 1, which systematically shows the identification, screening, eligibility, and inclusion process.

Data analysis was conducted by combining bibliometrics and qualitative content analysis. Bibliometric analysis was conducted using the Bibliometrix R-package to map publication trends, country productivity, author collaboration networks, and thematic structures. Quantitative indicators analyzed included the number of publications, annual growth, average citations, and the proportion of international collaborations. Furthermore, qualitative content analysis was applied to 21 selected articles to identify PBL designs, learning outcomes, and reported challenges and opportunities. This process was conducted using thematic coding techniques ( Almulla, 2023; Bristi et al., 2025; Gayed, 2025), where initial results were categorized and then synthesized into key themes, which were then triangulated with bibliometric findings. Thus, the integration of quantitative and qualitative analyses provides a comprehensive understanding of the position of electric bicycle conversion within the technology-based PBL landscape.

To ensure methodological rigor, this study applied the principles of rigor and reliability at every stage. The article selection process was conducted by two researchers independently, with an inter-coder agreement rate of 92%, and discrepancies in the screening results were resolved through joint discussion. This step ensured consistency and minimized subjective bias in study selection. Furthermore, the use of the PRISMA 2020 protocol enhanced the transparency and traceability of the review process, while the combination of bibliometric analysis and qualitative content provided triangulative validity ( Y. Chen, 2015; Nicholus, 2024). Visualization of results in the form of PRISMA diagrams, collaboration maps, and thematic maps was also used to clarify the results and improve replication of future research ( Widowati & Tyas, 2024). Thus, the methodology applied has a high degree of reliability and complies with the systematic standards required in reputable international publications.

The bibliometric analysis in Table 3 shows that research on technology-enhanced project-based learning with a focus on electric bicycle conversion is still in its early stages, with a total of 21 documents published in 12 sources in the 2021–2025 period. Although the annual growth rate shows a negative trend (−6.94%), the young average age of the documents (1.86 years) and the relatively high average citation rate (8,095 per article) confirm that this topic is attracting attention from the academic community. The presence of 136 Plus Keywords and 21 Author Keywords also demonstrates the broad scope of research, ranging from electric mobility to engineering pedagogy, positioning electric bicycle conversion not only as a technical innovation but also as an interdisciplinary learning medium oriented towards sustainability.

From a collaboration perspective, the involvement of 74 authors with an average of 3.52 collaborators per article, as well as 19.05% international publications, demonstrates a strong trend toward multidisciplinary and transnational research. The fact that all publications are scholarly articles confirms academic legitimacy and places the topic within the realm of serious formal research. Overall, despite the limited literature base, the indicators in Table 3 reflect the typical characteristics of a frontier research field: new, dynamic, receiving international attention, and rich potential to develop into a global trend in project-based STEM education.

Figure 2 shows the distribution of related scientific productionTechnology-enhanced project-based learning focused on electric bicycle conversions in various countries. Germany topped the list with 11 publications, followed by Italy (10), Switzerland (8), and the Netherlands (6). The dominance of these Western European countries indicates a well-established research ecosystem for integrating sustainable technologies into project-based education. These countries have strong traditions in engineering and renewable energy, making it natural for them to utilize electric bicycle conversions as an authentic medium to support STEM learning and build sustainability awareness among students.

In addition to Europe, contributions from Mexico (5), Slovenia (4), and Australia, Portugal, Slovakia, and Sweden (3 each) demonstrate a global diffusion of interest. This indicates that research trends are no longer exclusive to developed countries, but are also beginning to develop in countries with diverse educational and social contexts. The participation of non-European countries strengthens the position of the e-bike conversion project as a topic of cross-cultural relevance, with potential for adaptation across different educational systems. Overall, this distribution map confirms that e-bike conversion has become a bridge between the global issue of sustainable mobility and innovation in PBL pedagogy at the international level.

Figure 3 confirms that publication productivity in key countries is supported by distinct collaboration patterns. Germany, Italy, and the Netherlands emerge as the countries with the highest number of documents, with the majority of publications originating from international collaborations (MCPs). This indicates that research on electric bicycle conversion as a project-based learning (PBL) medium is not only built on national capacity but also through global networks involving cross-disciplinary expertise. This pattern demonstrates that the development of innovative learning media such as electric bicycle conversion requires multidisciplinary contributions from the fields of electrical engineering, renewable energy, and educational pedagogy.

In contrast, countries like Australia, Mexico, and Poland predominantly produce publications with a domestic focus (SCP), although they still show potential for connecting with global networks. Meanwhile, the presence of non-European countries like Colombia and Greece broadens the scope of collaboration, confirming that this research trend is inclusive and beginning to reach educational contexts in Latin America and Southern Europe. Overall, the intensity of international collaboration on this topic points to a clear direction: the conversion of electric bicycles as a PBL medium is increasingly seen as a cross-border issue, where the integration of global knowledge is key to strengthening its relevance and impact in sustainability-oriented STEM education.

Figure 4 shows the thematic structure of the study, which divides the main issues into four categories: motor themes, basic themes, niche themes, and emerging/declining themes. Central themes with high levels of relevance and development, such as “infrastructure European vehicles” and “providing travel in the EU,” emphasize that electric bicycle conversion projects have been closely linked to the sustainable mobility agenda in Europe. These themes are motor themes because they address not only the technical aspects of conversion but also their relationship to green transportation and infrastructure policies, making them relevant as a technology-enhanced project-based learning model that supports students’ understanding at the macro level.

On the other hand, basic themes such as “authors sustainable mobility” and “students – future – strategies” occupy fundamental positions, indicating that the literature consistently highlights the role of electric bicycle conversion projects in building sustainability awareness and long-term educational strategies. The theme “application engineering developed” emerged as a niche theme that focuses on practical engineering aspects and can be a vehicle for strengthening students’ technical skills in PBL. Meanwhile, topics such as “investments income charging” appear as emerging or declining themes, indicating areas that are still limited but have the potential to grow, for example in the context of integrating smart charging systems into the curriculum. Overall, this thematic map indicates that research trends are moving from mere technical experiments to a broader approach connecting engineering aspects, sustainability policies, and pedagogical strategies, thus strengthening the position of electric bicycle conversion as a new frontier in technology-based PBL.

The adoption and design of electric bicycle conversions as a project-based learning (PBL) medium varies widely across educational contexts, from secondary schools and vocational education to higher education and community-based learning. In higher education, particularly in engineering and technology, electric mobility projects are integrated as capstone assignments and applied learning, requiring students to develop concrete prototypes based on renewable energy. The results not only enhance motivation, technical skills, teamwork, and entrepreneurial orientation, but also present challenges such as limited access to materials, reliance on simulations rather than real-world laboratories, and communication difficulties with mentors.

At the vocational and secondary education levels, PBL is more directed at connecting theory with authentic practice. In TVET, the application of real-world engineering assignments has been shown to strengthen students’ problem-solving, collaboration, and applied skills, while in secondary schools, physics experiments based on mobility problems enhance conceptual understanding and critical thinking skills. However, constraints such as limited facilities, curriculum rigidity, and uneven student preparedness remain major obstacles. In the context of transdisciplinary and international collaboration, electric bicycle conversion projects and sustainable mobility issues are positioned as cross-cultural learning platforms oriented toward the Sustainable Development Goals (SDGs). Through learning labs that bring together students from the Global North and Global South, this challenge-based learning has successfully fostered intercultural competency, sustainability awareness, and collaborative skills. However, differences in institutional capacity, limited resources, and asymmetry in partnerships remain recurring obstacles.

Similar adoption has also emerged in informal, community-based contexts. Volunteer initiatives such as greenway reuse and eco-friendly transportation programs demonstrate how PBL can foster inclusivity, intergenerational bonding, and local economic impact. However, reliance on volunteer labor, uncertain environmental conditions, and weak stakeholder coordination limit their sustainability. Overall, the results summarized in Table 4 highlight four key PBL design characteristics of the e-bike conversion project: (1) authenticity, with an emphasis on solving real-world challenges; (2) collaboration, both within academic and community settings; (3) integration of sustainability, encompassing renewable energy, climate mitigation, and social values; and (4) scalability challenges, particularly related to resources, curriculum, and program sustainability. In terms of learning outcomes, the e-bike conversion project not only improved cognitive skills such as problem-solving, critical thinking, and the application of engineering competencies, but also strengthened affective and social aspects such as motivation, sustainability awareness, intercultural competency, and cross-disciplinary teamwork skills.

The integration of an electric bicycle conversion project into Project-Based Learning (PBL) results in learning outcomes spanning cognitive, technical, and 21st-century skills. Referring to Table 4, from the cognitive aspect, studies in secondary education show that mobility-based physics experiments within a PBL framework can strengthen understanding of energy concepts while enhancing higher-order thinking skills ( Jalón Oyarzun et al., 2023). In higher education, the application of renewable energy system design simulations and the development of solar and wind-powered electric vehicle prototypes expand students’ abilities in complex problem-solving and data-driven decision-making ( Pollák et al., 2021; Ariza, 2023). From a technical perspective, electric bicycle conversion provides an authentic platform for applying engineering knowledge, from electronic circuit design and energy system integration to solving real-world engineering problems. This is further reinforced in the TVET context, where students acquire applied skills through engineering assignments that mimic industrial conditions ( Müller et al., 2024). This activity confirms that e-mobility-based PBL brings theory and practice together more deeply than conventional learning, while strengthening cross-disciplinary technical skills.

Furthermore, the integration of this project also strengthens 21st-century skills. Team collaboration in prototype development and international learning labs has been shown to foster communication skills, cross-cultural collaboration, and leadership in collective problem-solving ( Lemonde et al., 2021). At the community level, PBL-based initiatives have demonstrated significant contributions in increasing motivation, sustainability awareness, entrepreneurship, and social skills such as inclusivity and intergenerational solidarity ( Junaid et al., 2025). Thus, the learning outcomes of the electric bicycle conversion project extend beyond the cognitive and technical domains to the affective and social dimensions that characterize 21st-century skills, such as creativity, collaboration, and sustainability literacy. Overall, these findings demonstrate that the integration of electric bicycle conversion within PBL can produce holistic learning outcomes: strengthening conceptual understanding and critical thinking skills (cognitive), enhancing engineering design and application capabilities (technical), and fostering collaboration, communication, entrepreneurship, and sustainability awareness (21st-century).

The results of this systematic review demonstrate that the conversion of electric bicycles as a project-based learning (PBL) medium has strategic potential to strengthen the integration of STEM education with the global sustainability agenda. Bibliometrically, although the number of publications remains limited and shows a negative growth trend, the tendency of international collaboration and thematic diversity confirms that this field is entering a frontier research phase with new, dynamic characteristics and potential for widespread growth. The dominance of publications from Western European countries, such as Germany and Italy, demonstrates strong policy support and a research ecosystem in the field of sustainable mobility, while the involvement of countries in Latin America, Asia, and Africa indicates the diffusion of innovation into more diverse educational contexts. From a pedagogical perspective, the adoption of e-bike projects in higher education has proven effective as capstone assignments that develop technical competencies, interdisciplinary collaboration, and entrepreneurial orientation. In vocational and secondary education, these projects serve as a bridge between theory and authentic practice, strengthening conceptual understanding and critical thinking skills. While in non-formal, community-based settings, they serve as a means of increasing inclusivity, intergenerational solidarity, and contributing to the local economy. Thus, the electric bicycle conversion project can be categorized as an adaptive, authentic, and socially relevant PBL model, consistent with international literature that emphasizes the importance of the connection between theory, practice, and real context in PBL.

In terms of learning outcomes, the integration of the e-bike project has been proven to have a holistic impact on cognitive, technical, and 21st-century skills. The cognitive domain is demonstrated through increased conceptual understanding, analytical reasoning, and higher-order thinking skills; the technical domain is reflected in mastery of renewable energy systems, prototype design, and engineering problem-solving; while the 21st-century skills domain includes collaboration, cross-cultural communication, sustainability literacy, and entrepreneurial orientation. This achievement profile not only aligns with the meta-analysis on the advantages of PBL in developing HOTS but also extends it by emphasizing an explicit sustainability dimension. However, several structural challenges still need to be addressed, including limited laboratory resources in higher education, curriculum rigidity and uneven student readiness in vocational and secondary education, capacity asymmetries between Global North and Global South institutions in international collaboration, and reliance on volunteers and weak coordination within the community. These conditions emphasize the need for systemic support in the form of teacher capacity development, more flexible curriculum reform, and education policies that support the integration of PBL into the sustainable development agenda.

The theoretical implication of these findings is the need to expand the conceptual framework of PBL by incorporating dimensions of sustainability and transnational collaboration as integral parts of learning design. Practically, educators can utilize electric bicycle conversion projects as an authentic learning medium to increase students’ motivation, technical skills, and sustainability awareness. From a policy perspective, it is crucial for governments and educational institutions to provide infrastructure support, curriculum flexibility, and teacher professional development programs to ensure systemic adoption of PBL. Future research should expand the context of e-bike-based PBL implementation in primary and non-formal education in developing countries, conduct longitudinal studies to measure long-term impacts, and explore the integration of digital technologies such as IoT, big data, and AR/VR simulations to enrich the learning experience. Furthermore, a more equitable global collaboration design through resource-sharing and capacity-building mechanisms is needed, as well as the development of holistic evaluation instruments capable of measuring outcomes not only in cognitive and technical aspects, but also in sustainability literacy, social entrepreneurship, and intercultural competence. With these steps, electric bicycle conversion as a PBL medium has the potential to evolve from a fragmented pedagogical innovation into a transformative educational strategy that supports the achievement of sustainable development goals at the global level.