Whisk the ketchup, Big Red Soda, cider vinegar, hot sauce and liquid smoke together in a large bowl. Add to the slow cooker.
In another bowl, whisk the salt, pepper, cumin, paprika, and cayenne. Stir in the garlic and onion and cover with foil. Microwave for 4 to 5 minutes until onion is tender. Add to the slow cooker. Stir to combine.
Add the chuck roast to the slow cooker.
Cover and cook over low heat until the beef is fork tender, 5 to 7 hours.
Remove the beef from the cooker and shred with 2 forks. Return to the slow cooker and toss with the sauce.