It depends a lot on how long you expect it to take you . . . and there's a big difference between 35 and 50 miles. I used to do a 33 mile ride with 2,000 feet of climbing with my club on Saturdays. It took an hour and 50 minutes or so to complete. I brought two bottles with "fuel" in them (never just water unless it was a super hot day and I brought a third bottle to pour on my head, which makes a HUGE difference). I used to use Cytomax Lite, but they don't make it anymore. I haven't been able to ride long enough to require "fuel" in over a year, but just today my doc recommended Activate Workout for when I do (found at grocery stores she said). It's natural with no sugar, chemicals, etc. and I can't have sugar right now. My husband uses EFS, though, and swears by it.

Anyway, for 2 hours out I never brought food with me. Sometimes I had a gel, an Accel Gel specifically, because it's the only gel I'm aware of that has protein in it. (Protein is good for your muscles)

I have read that pistachios are very good for mid-ride snacks to keep you going, if you want to avoid processed stuff. There's something about them that gives you just what you need (can't remember what, other than protein.) A half a peanut butter sandwich would be good, but you have to be careful not to smash it in your jersey! Bananas are good, too. It is common to find peanut butter and jelly sandwiches and bananas at SAG stops on organized rides.

I have often stopped at Subway half way through long ride. Never eat too much, though, or your body will be expending energy to digest instead of sustaining you through the rest of your ride. My friend and I have shared a 6" before, or gotten a small breakfast sandwich.