Abstract: Collisions with dust particles in retrograde orbits cause space erosion on stony meteoroids in addition to the particle drag which causes drift toward resonances. The spacing between resonances determines the maximum drift time and sets upper limits on the neon-21 cosmic ray exposure (CRE) ages for meteoroids less than ~1 m in radius, while space erosion controls the limit for radii greater than ~1 m; the limits accord well with the measured CRE ages of stony meteorites.