Lots of good advice already in this thread.

The general rule is that you need to do something three days a week to get stronger at it, whatever it is. On the other end, you need at least one recovery day a week as well - activity is what stimulates your body to rebuild itself stronger, but it's during the down time that the rebuilding actually happens. The older you are, the more recovery you will need between long and/or hard efforts.

Since you're planning an event with consecutive long rides, you'll want to do at least some of your riding on consecutive days. That will accustom you to going long when your muscles are already tired.

While you're training your muscles, you'll also be learning what works for you as far as nutrition and hydration. On a long day you need to take in water, electrolytes and food, but you may or may not feel thirsty or hungry. Learn to recognize the symptoms of dehydration and "bonking" and head them off before they happen.

I personally can't imagine riding so long without toe clips or clipless pedals (clipless are much safer IMO since you don't need your hands to get out of them) ... but lots of people do it. It's whatever works for you. Don't let peer pressure dictate your choice of equipment.

There is no "average speed." That's dependent on terrain, equipment, and most of all on the riders involved. Some groups are happy to tool along at a sub-10 mph pace. Other groups average 25. Most groups are somewhere in between, but that's a BIG range. Find out what your group plans to do and aim for that. Train with them sometimes to get used to not only their pace, but their individual riding habits.

I very much disagree with the idea of drafting at your level. Drafting is an ADVANCED skill that requires razor-sharp bike handling. It's very efficient, but it can also be extremely dangerous. If you want to learn (and if your group practices pacelining, you probably should), take a bike-handling class such as the League of American Bicyclists offers; practice handling skills on your own as much as you train for strength and endurance; and NEVER draft someone closely whose riding habits you don't know.


Good luck and enjoy.