A three-week unicycling training was associated with (1) reductions of gray matter volume in regions closely linked to visuospatial processes such as spatial awareness, (2) increases in fractional anisotropy primarily in the right corticospinal tract and in the right forceps major of the corpus callosum, and (3) a slowly evolving increase in cortical thickness in the left motor cortex. Intriguingly, five weeks later, during which participants were no longer regularly engaged in unicycling, a re-increase in gray matter was found in the very same region of the rSTG. These changes in gray and white matter morphology were paralleled by increases in unicycling performance, and by improvements in postural control, which diminished until the follow-up assessments. Learning to ride a unicycle results in reorganization of different types of brain tissue facilitating more automated postural control, clearly demonstrating that learning a complex balance task modulates brain structure in manifold and highly dynamic ways.