Ive been riding for a year and such, and I find that for me( on a road bike, riding a flattish commute, 17 km) I dont eat in morning, except banana and grape juice. Ill eat after ride, having a protein shake. I was protein starved so adding two a day( shakes ) helped me, but I dont eat any grains or rice or corn.
I work on my feet all day, and Im pretty tired for commute home. The last 5 km are SOO hard( and uphill and a headwind to boot!)!
It takes time to build muscles and endurance.
I find if I eat for rides under two hours, I get sluggish.
Im pretty tired after my two hour ride on weekends( when I go!), and I eat before that. Its getting easier but at least I dont need a nana nap anymore after it( I use to pass right out!).
Also, how fast are you going and what gearing?I once had a ride when I got home, I thought, man, Im wasted! Turns out I rode in the hardest gear, all the way home , uphills and headwinds and all.