Highlights: • Bunch thinning does not increase the contents of molecules of interest in the grape. • Reducing yield induce a loss of metabolites with no fruit quality gains. • Aromatic precursors represent a small fraction of the non-structural C of the grape. • The manipulation of sink/source ratio does not change the metabolic flows to the fruit. Abstract: Despite their low concentration, secondary metabolites are essential to the organoleptic quality of grapevine fruit. Anthocyanins of the fruit skin cells are the principal components of the pigmentation of the red grape. Glycosylated aroma precursors (GAPs), i.e. alcohols, C13norisoprenoids, phenols and terpenes determine the aroma potential of the juice and the resulting wine. The regulation of the sink/source (S/S) balance is considered as a one of the more powerful tools to adapt grape composition to technological objectives. In this study, we have manipulated the S/S of Vitis vinifera varieties and quantified the changes on the accumulation of secondary metabolites at the arrest of phloem unloading in the grape. The results demonstrated that the manipulation of the S/S doesn't de-correlate the accumulation of secondary versus primary metabolites. Decreasing S/S drastically limited the accumulation of either primary metabolites (till-70%), anthocyanins (till-70%) and GAPs (till-81%) per plant, with a huge production shortfall of molecules of interest per cultivated area unit.