Make the simple syrup: combine 120ml white sugar and 120ml hot water in a heatproof container and stir until the sugar fully dissolves. Set aside to cool completely. (This yields approximately 180ml of 1:1 simple syrup - use 120ml for this recipe and reserve the rest.)
Slice one orange, one lemon, and one lime into wedges, removing any seeds.
Pour the red wine, 120ml cooled simple syrup, and calvados into a large pitcher.
Add the citrus wedges and stir gently to combine.
Refrigerate for at least 2 hours (up to 4 hours) to allow the flavors to meld.
Just before serving, top with grapefruit soda and stir lightly once to preserve carbonation.
Serve in tall glasses over ice with a straw.
For a deeper, more complex sangria, swap in a Spanish Garnacha or Tempranillo - their fruit-forward profile and soft tannins integrate beautifully with citrus and calvados. Macerating the fruit overnight amplifies flavor significantly without any extra effort.
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