Originally Posted by
datlas
Honestly, for 25 miles you just need 1 bottle of water. You don't need any calories, maybe an electrolyte tablet if it's really hot out. Your body has more than enough stored glycogen for a relatively short ride like you describe.
This is about 90 min at the OP speed.
A fat adapted person needs nothing. The OP is most likely not fat adapted.
Internet search says stored glycogen lasts from 1-4 hours depending on the person, diet etc. For a cyclist - it is at the low end. That the OP asked I'd guess a little simple carbs might be good for them. It won't hurt.