[aigel]

You will be a lot more hungry - take some healthy but nourishing snacks. I did a 24 mile round trip a few times but found it too long. I was very tired by mid day and riding home after a 10 hour day was a real drag. 5 miles and an 8 hour job is about ideal IMHO. Also, if you haven't ridden that kind of mileage much, start slowly - once a week - and then add a day every 2 weeks.

What jyl said on the visibility. And stay away from cars if possible - i.e. take the long way if there is a bike route or park to go though.

G