Coke is loaded with sugar, i.e. quick energy. Some drink it flat to avoid the belches afterwards!
For a 20 mile ride, I reckon water is enough. Take a banana, flap jack or muesli bar kind of thing (like the aforementioned Jordons) just in case... or just to enjoy when/if you have a break. If you're really concerned, pick a route that includes shops or petrol stations. Pretty much any food is better than nothing.
And just enjoy it!
For a 20 mile ride, I reckon water is enough. Take a banana, flap jack or muesli bar kind of thing (like the aforementioned Jordons) just in case... or just to enjoy when/if you have a break. If you're really concerned, pick a route that includes shops or petrol stations. Pretty much any food is better than nothing.
And just enjoy it!