ðˈɛɹfoːɹ, pəzˈɪʃənɪŋ ðə smˈɔːlɚ wˈiːl æt dˈɪfɹənt pˈɔɪnts ɐlˈɔŋ ðə lˈɑːɹdʒɚ wˈiːlz sˈɜːfɪs vˈɛɹiz ðə ɡˈɪɹ ɹˈeɪʃɪˌoʊ.
Therefore, positioning the smaller wheel at different points along the larger wheel's surface varies the gear ratio.