Technically, any race over 1 hour and you'll need to eat. Depending on size it is estimated that you should have 100 to 200 cal per hour in addition to your sport drink. For a sprint tri you're really only looking eating on the bike. Shot blocks should be fine. You should have something before the race if swimming is an issue. A gel or a few shot blocks would work for that too. If it's hot, be sure to use electrolyte drink of some sort on the bike and you may want some for the run. Myself, I don't bother eating or drinking anything on a sprint run. The run's only 30 min, I won't even digest whatever I eat on the run in time to use it during the race.
So start with things that you like (shot blocks) and maybe experiment with some gels. I like accelerade strwberry kiwi. It's not really sweet and the consistency is thinner so it goes down better than some of the thicker gels.
Hope that helps.
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