If you are looking to successfully complete your first century, there are some simple steps you can complete to get to finish line feeling comfortable and in as little pain as possible.
Choose your course carefully. If you will be participating in an organized ride, make sure you research the course thoroughly. Talk with other cyclists and Google reviews of the actual ride. Look at the course profile to see how many climbs there are and if you are comfortable with them. I would not pick the Triple Bypass Ride of Colorado as my first century for example. Find out how well organized the ride is and what the rest stops will be stocking.
Make sure you train. My buddy Curt is a fantastic athlete and has that mental edge that you need to go one step beyond your pain threshold. Because he lives in New York, he has a tough time finding places that will allow him to ride at a consistent effort for prolonged periods of time. If you want to be comfortable for an entire century, you need to be able to schedule time to ride long. You can finish on a long ride of 40+ miles like Curt did, but I am sure even he would tell you that it would be better to get as many long rides in you as possible. I would look to complete at least three rides of 75 miles before the century. This will help your body acclimate to a high level of output for a prolonged period of time.
Practice everything – especially nutrition. You will hear tons of people tell you, "Do not try anything new on race day," and this is true of a century as well, even if it is not a race. Come the day of your event, you should know how many calories your body can process in an hour during exercise and the best way to deliver those calories. You should know what your stomach is telling you if you feel bloated or hungry and the best way to solve that issue. You should always put together a feed plan and follow it closely come the day of your event.
Get a good group of same level people around you. It is tough to ride with people who are much faster or slower than you are. If you have people of different abilities and experience levels, you will need to make a commitment at the beginning of the ride to stay together and not push anyone outside of what they are comfortable with. Our group was pretty good with this. We did get separated a couple of times, but we were determined to finish together and everyone crossed the line. When you ride with friends, it makes the miles quickly pass by.
Try and ride with your crew before the big day. The CASVAR was a good experience for our group. This is the core group that we will be riding LOTOJA with and we learned that it takes time to work on paceline strategies together. We could put people out on front for 2:00 and then have them rotate without any problems, but quick rotations like: 15 when the wind was really strong was not possible because we had not practiced these together as a group.
Get a tune-up on your bike a week before your event. It always helps to have someone check your cables, make sure you are all greased and lubed up, and that all your moving parts are working. There is nothing more annoying to me than to have someone in my group's chain start to creak because it is dirty. Do not be that person in your group. Simple maintenance may be all that is required, but please, for the love of everything that is holy, make sure your bike is running in stealth mode – as quiet as possible.
Ride within yourself for the first 75 miles. After the 75 mile mark, you can put the hammer down, but for your first ride, resist temptation and dial your effort back. You may finish a little slower than your abilities allow, but you will finish. Take your time and soak in the experience. Talk with other cyclists around you, make sure people who are pushed over to the side of the road have what they need, and just enjoy yourself. It will make the experience that much sweeter. Once you hit the 75 mile mark, evaluate your mental and physical status. If you are still feeling good, put the hammer down and fly.
Celebrate your victory. No matter how fast or slow you were, regardless if you hit your goals or not, you still made it 100 miles. You really should celebrate. At the finish, kick back with your friends, do a little dance, make a little noise, and get down. You may not be able to walk upright, but you still finished and should be proud of your accomplishment!