Nutrition on the road - What, How and Why?

I'm not completely convinced by this. If you're taking it easy but eating a lot of sugar, you could be absorbing much more than you're burning, particularly if you naturally have a fat burning metabolism. Once your liver and muscles are full of glycogen, what's going to happen with the extra ? Nothing good, I suspect.

I've seen articles claiming that insulin spikes don't happen during exercise, but none that were very clear on how hard the exercise needs to be. Does strolling slowly down the street count ?

tl;dr eating all the sugar may not be for everyone

Define "a lot" though.

Even at a snail's pace the energy requirements for a 200k ride are quite high - get tester to do the maths. How much energy is contained in a kendal mint cake?

I'm sure there's data on this but I don't have time to track it down and I don't know off the top of my head what intensity levels match what amount of glycogen use/blood sugar levels.