This study offers a comprehensive exploration of bike-sharing service equity and influential factors determining usage patterns in Washington, DC, particularly within disadvantaged neighborhoods. A blend of statistical methods, including multiple regression models, generalized least squares models, decision trees, and random forests, illuminates the key contributors to bike-sharing ridership. Further assessments utilize the Two-Step Floating Catchment Area (2SFCA) technique to appraise spatial accessibility to bike-sharing stations, while analysis of membership and trip duration underpins an examination of system usage and affordability. The investigation reveals that the bikeshare system in DC still hasn’t achieved equity goals, and areas of lower deprivation do have better access to bike-share stations. Simply increasing the number of bike-sharing stations and parked bicycles doesn't significantly affect ridership in disadvantaged areas, and it's more effective to improve relevant infrastructure first before expanding the number of stations or bikes. These findings aim to provide valuable insights for policymakers and planners to improve the equitable distribution and usage of bike-sharing services.