1. Preheat oven to 400°. Remove tops and ends of beets, and wash. Place beets and onion on a foil-lined baking sheet. Drizzle with oil, and toss to coat. Cover tightly with foil. Bake 40 to 50 minutes or until tender.
2. Transfer beets, onion, and any liquid to a bowl; cool 15 minutes. Peel beets; cut into 1/4-inch-thick slices. Cut slices into 1/4-inch-wide sticks. Layer beets and onion in 4 (1-pt.) widemouthed jars, filling to 1/2 inch from top.
3. Bring sugar, next 2 ingredients, and 1 1/3 cups water to a boil in a medium saucepan, stirring often. Boil 5 minutes or until sugar dissolves. Pour into jars, just covering beet mixture. Discard any remaining vinegar mixture. Add 2 cloves and 1 cinnamon stick to each jar. Cover with lids; screw on bands. Chill 2 days before serving. Store up to 1 month.