Preheat oven to 350 degrees. Bake pecans in a single layer on a sheet pan for 5 to 7 minutes or until lightly toasted and fragrant, stirring halfway through. Set aside to cool.
Cook pasta according to package directions and drain.
Meanwhile, cut broccoli florets from stems, and separate florets into small pieces using the tip of a paring knife. Peel away tough outer layer of stems, and finely chop stems. Slice grapes in half and dice the onion. Place cut vegetables and fruit into a large bowl. Add hot cooked pasta.
In a small bowl, whisk together mayonnaise, sugar, red wine vinegar, and salt. Pour dressing over pasta and veggies, toss to coat. Cover and chill for 3 hours.
Just before serving, stir in cooked bacon and toasted pecans.
Cook's Note: You can substitute sesame seeds or slivered almonds for pecan if desired.