Cook pasta according to package instructions. Once cooked, drain and rinse with cold water. Set aside.
In a large mixing bowl, whisk together mayonnaise, granulated sugar, apple cider vinegar, salt, and pepper until smooth and well combined.
To the dressing, add cooked pasta, coleslaw mix, diced red onion, and sliced cucumber. Toss to coat everything with the dressing.
Cover and chill for at least an hour before serving.