Ya know steader, I have re-read this post and I have found I would like to ask you a question.
What exactly does your diet, exercise, hydration, and rest look like on a daily basis?
Diet: If your diet needs work, then you are not giving your body the fuel it needs on a DAILY basis to be able to sustain
intense exercise.
Exercise: If you're not exercising on a daily basis, and in your case,
strength training and cardio, you are not giving yourself the best chance you can for your cycling.
Hydration: You need to drink a minimum of 1/2 gallon of water a day. More if you exercise intensly. Water keeps our muscles saturated in water, avoiding hydration, which leads to the avoidance of fatigue.
Rest: Any time we want to achieve a physical goal, we have to have a proper diet and exercise program, proper hydration, but also enough rest so we have enough energy to accomplish what we want to accomplish.
All of this comes as a package deal: Diet, exercise, hydration, and rest.
That doesn't mean we have to be perfect in each area, but when all of those areas are at a high level, we give ourselves more than a chance to perform at our best, which in your case, is cycling without fatique.
It takes much more than just eating the right foods before and during an activity. If all of these areas are not at certain levels, then even with what would normally be the right food, you will still experience the same result.
Just something to think about.