When suprasegmental and contextually induced variations interact, coarticulation of consonant and vowel undergoes more complex, and often subtle, resistances and assimilations. This study empirically documents the separate effects of increase in speech tempo on C-locus and V-midpoint F2 patterns. Two female speakers of American English each produced 810 tokens [3V1* 3tops * 10V2 contexts * 3repetitions). Modified locus equation regression metric was employed to dissociate the effects of tempo on the vowel F2midpoints relative to the F2onsets at the CV boundary. The analyses uncovered two main systematic changes to F2onsets and these were attributed to (a) rate-induced reduction of the vowel space, (b) rate-induced changes on coarticulation per se.