Try to drink 500ml of fluid for every hour on the bike. You lose moisture not only by sweating but also through respiration. If you don’t replace it your performance will suffer. It’s better to drink a little and often rather than gulping down large volumes of fluids once or twice an hour.
Don’t forget to eat (again, little and often). You will be burning lots of calories so replacing them will enable you to sustain a decent pace.
The market is swamped with expensive products but it’s not necessary to part with cash here. Bananas are great, homemade flapjacks, dried fruit and jelly babies all make ideal snacks too.
Top tip: remember you can always set an alarm every 15 minutes as a reminder to drink and eat.