Using a vegetable peeler, shave 4 long, thin ribbons from cucumber; set aside. Combine lime zest, sugar and 2 lemon wheels in a cocktail shaker. Add gin and lime juice and fill shaker with ice. Cover and shake for about 20 seconds.

Strain into 2 ice-filled Collins glasses. Top off each with club soda. Gently stir to combine; garnish each with 2 reserved cucumber ribbons and remaining lemon wheels.