If you’ve never ridden long distance before, don’t make the mistake of hopping on a new touring bicycle and heading out on a 50-mile ride, even if you are athletic enough to make it that far without training. Because of the above-mentioned factors, especially saddle-soreness, it is much better to start out modestly and work your way up to longer rides. Begin with short rides of 15 to 20 minutes in duration and see how you feel after that. After the first week you should be able to ride an hour or so at a time. It’s best to alternate your riding days so your body has time to recover between longer rides. You could ride 15-20 minutes on Monday, Wednesday and Friday, and ride an hour on Tuesday, Thursday, and Saturday. Try riding faster on the days when your rides are short, but take it easy and enjoy the scenery on the longer days. After the first week or two, you can gradually start pushing a little harder and may even be ready to extend the length of your rides.
In moderate terrain, you should be able to average about 15 miles per hour on paved roads, so once you work up to doing three rides a week of at least 20 miles, you won’t have to spend more than about an hour and twenty minutes on the bike on those days.