[Otter74]

I was going to chime in yesterday but there is a lot of good advice here so I'm not sure I can add anything that hasn't already been said.

Like you, I used to not know how to pace myself. I grew up riding in Atlanta, which is hilly but all the hills are short. Then Michigan, which is flat. I went out to Colorado and would spend much of a day riding the P2P and would kill myself 1/3 of the way up the long grades, trying to do it in the middle ring - I have never been much of a spinner, and was used to a fairly high pace. Eventually figured out that it was easy if I used the granny ring, spun more, and slowed down. Went back some years later and it was all easy-peasy.

You don't have much time to train, but I think if you can do half the distance easily by the week before the event, you will be OK with the full distance, even though the difference feels bigger than 2x.

As far as food goes, I will mention that I've found dill pickles to be very good for electrolytes, given that I vastly prefer real food to gels and goo and so on.