+1 on at least two pairs of shorts.

If it were me, I would take the extra spoke and spoke wrench, and a chain tool. Something to boot a tire with might be handy, as would a mini pump on the bike.

I'd also bring sunscreen, sunglasses, and bug stuff, but that may be a matter of personal preference. I burn easily, have light eyes, and mosquitos think I'm the main dish.

Have fun!