From what I understand up to an hour of moderate riding with relatively no heat is fine with just water. Over an hour, or less than an hour at higher intensity and/or heat, you should have electrolytes.

I was just researching this yesterday as I am just getting back into rides that are requiring more than just water. I really need to avoid sugar, so researched what my options were. I knew coconut water had electrolytes, but thought I'd need something more. Apparently not. However, if I need "energy" because my rides are particularly long or intense, then I need to figure out what non-sugar options I have for that. I've read pistachios are a perfect fuel for cyclists, but I have an intolerance to them. Figures. I used to use regular sports drinks, Cytomax Lite and when they quit making it, EFS, but I'm trying to go natural now.