For long rides, I mix up single-servings of bike food (maltodextrin and protein powder 7:1 by weight, same as Hammer Perpetuem) for one bottle and half-strength gatorade for the other bottle. Anything over 200k I'll plan on one bottle of each every 40 miles or so. I do a lot of fasted 100k's, so I agree that you don't really need nutrition for a 75 mile ride if you're in decent shape.