how hard IS a century?

[mimitabby]

Well, I haven't done 100 miles proper... but I've done 70-80-85 miles... and I did it with a Camelbak and 2 water bottles. Of course, I filled up along the way.

When I ride, after the first hour (since I have breakfast in my tummy) my goal is to try to consume 200 calories an hour... that can be in the form of food/gels/sports drink.

The key is to stay properly hydrated, eat before you get hungry and rest when you need to.

KSH gives darn good advice. Camelbaks really make it easier to hydrate. But you're going to have to refill it from time to time!
it's really hard for me to eat enough to keep going all day; and oh yeah, a 6 hour century is REALLY FAST.. Typically, unless you are a reallly fast rider, figure about 12 mph ~ 8 hours. slower for lots of climbing, faster for tailwinds.
and headwinds can ruin everything.