Bearing surfaces experience degradation in terrestrial and aerospace environments due to mechanical wear, and their eventual failure has commonly been a life-limiting factor in spacecraft. Although many different materials like superalloys and ceramics have been developed to address this need over the past decades, drawbacks of high density or brittleness remain. Recently developed low-density superelastic Ti-based bulk metallic glasses show promising mechanical properties and here we systematically investigated them in comparison with conventional gear or bearing materials (Nitinol 60, Vascomax steel and Ti-6Al-4V). Wear tests are performed using pin-on-disk tests in air and under vacuum to explore changes from terrestrial to space-like conditions. This talk will review the experimental results, as well as the mechanisms of wear as analyzed by subsequent microstructure characterization.