Spray the inside of a 5- to 6-quart slow cooker with cooking spray.
Remove inner skin from the ribs. Mix brown sugar, pepper, liquid smoke, garlic and salt together in a bowl and rub this mixture onto the ribs. Cut ribs into 4 inch pieces, then layer ribs and onion in the slow cooker. Pour cola over everything.
Cover and cook on a low heat setting for 8-9 hours or until ribs are tender. Remove the ribs from slow cooker, and drain and discard the liquid.
Pour the BBQ sauce into a shallow bowl. Dip each of the rib pieces into sauce. Return the ribs to the slow cooker. Pour any remaining sauce over the ribs, then cover and cook on low for 1 hour.
Sorry, there is no nutrition information available for this recipe.