Place rinsed and drained spinach in a large bowl.
Sauté onion and red pepper in a little olive oil in a skillet while the pasta is cooking.
Drain the pasta well, then add both the pasta and vegetables on top of the spinach while they're hot.
Add bacon, feta cheese, sun-dried tomatoes, shredded chicken, and toss well.
Combine the olive oil, vinegar, salt and pepper, and mix well.
Pour over salad and toss to combine. Serve warm or cold.