Most races will provide nutrition and water along the course, but it’s a good idea to have a water bottle (or two) on your bike, and perhaps a hydration belt when running. Energy chew or gels are a smart transition area item and can be digested quickly. Don’t bring anything you haven’t tried before – just like with your tri clothing, you’ll want to have tested out the snacks you’ll be relying on beforehand so there are no surprises.