I've started doing a weekly 25 mile bike ride. The first time I went
that far I ate no food along and only drank water the way and felt
utterly exhausted.

I've found that I start feeling a bit fatigued about half way through and
I've taken to eating a Turkish Delight washed down with a bottle of
Lucozade which seems to give me a noticeable boost of energy.

What does everyone else do to keep their energy up on long rides?