Oatmeal is one of the easiest things. Not the sugary stuff mind you but the natural plain stuff. You can add whatever you want to flavor it. I add whey protein and then it tastes like whatever flavor I put in there. I throw in some ground flax too for EFAs.

If you end up biking on an empty stomach you should at least take some powdered BCAA mix in my opinion so your body has those available and doesn't need to break down any muscle tissue.