The concept of the 15-min city refers to an urban environment where residents can access essential amenities within a 15-min journey from their homes. Most existing studies on the 15-min city assume walking as the default mode of transport, often overlooking cycling alternatives such as bike-sharing. Given the growing global popularity of bike-sharing, it is crucial to examine how this emerging form of micromobility contributes to the development of 15-min cities. This study proposes a methodological framework to measure and evaluate the 15-min cities in the context of dockless bike-sharing. The framework is applied to 41 cities in Zhejiang Province, China. Our findings indicate that, under the walking scenario, 1,887 spatial units qualify as 15-min units, compared to 3,295 units under the bike-sharing scenario and 9,852 units under the private-bike scenario. Correspondingly, 10.26 million, 15.58 million, and 24.56 million residents, respectively, can access ten types of essential amenities within 15 min. The majority of 15-min units are concentrated in city centres and built-up areas. Based on the analysis of 15-min units, bike-sharing significantly enhances residents’ accessibility to specific essential amenities, such as post offices, particularly benefiting disadvantaged population groups. Furthermore, the convenience and capacity of key parking locations that support 15-min cities vary across different urban areas. Overall, the results demonstrate that bike-sharing facilitates the development of 15-min cities, although there remains scope for improvement compared to the optimal scenario. This study offers valuable insights for transport planning and policymaking aimed at fostering 15-min cities.