A half banana before the ride? Is that a snack, or breakfast? For a morning 35-45 mile ride, at a fairly hard effort, I'd eat a normal breakfast, around 300-400 calories. I usually bring a 250 cal Clif bar. I fill one bottle with a weak gatorade type drink mix, about 100 calories, and a second bottle of water. I have a extra 100 cal bar in my seat bag, and I've eaten it, too, occasionally.

Recently, I've been trying out long "zone 1 or 2" longer rides at a very easy pace, with breathing just slightly elevated. It's interesting that those rides don't make me hungry at all. They are good for training the body to use stored fats for energy.

...Now I'm remembering the 40 mile Saturday cycle club ride that I rode regularly when I started getting serious about riding. It would wipe me out. I'd come home starving and eat a huge meal, then take a nap. That was 6 or 7 years ago.

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You could add a few miles to the shorter weekday rides, and do one 40 mile ride on the weekend, and then a 45 mile the next week. If those two rides weren't a struggle to complete, you could hit the 50 mile mark the next week pretty easily.

I think that riders that can handle regular rides 35 miles with no problems can do a 50 mile "goal" ride the next week. It's more being able to ride that many hours instead of a strength problem.