You can eat whatever you want for your runs or rides.Let me ask you. If I going for a 24km run or 160km ride , what should I eat for immediate energy?
I do not need to eat except drink water with electrolytes.for the run.
21/24km run is hugely different from 160/180km ride in terms of time to finish it.
One can do with just couple of gels for the 6 ,7 hours ride if fat adapted. Its to prevent bg from falling too drastically.