realskiers

Jim, if you can do a 50-60 mile ride, you can do a century. Averaging 15mph is very doable even if your typical road ride is 13-14mph. In a large organized century, pace lines just "happen". You go about 30% faster when in a pace line. At 15 mph you are looking at just under 7 hours. I am sure there are road clubs in your area that help riders get comfortable in pace lines if you do not have much prior experience.

Mistakes I have seen by inexperienced century riders: 1) Going out too fast. You can get caught up in the pack going way too fast with your heart rate redlining. Easy to get in a pace line early that is way over your ability. 2) Spending too much time at rest stops. The farther into the ride, the faster your legs tighten up at rest stops, the harder to get going again. 3) Carrying too much stuff. Most rest stops are 20-25 miles interval. Carry as much stuff as you would for a 20-25 mile ride at home. Carry a minimal amount of tools, that is what the sag wagons and rest stop mechanics are for. Most sag wagons carry floor pumps - much better than a mini frame pump or CO2 cartridge. Most bigger centuries have dispatchers for the sag wagons, carry a cell phone and call the sag wagon if you have a flat. The coldest temperature is usually at the start - dress for it and plan to peal down as it heats up. The only exception is for potential rain. If big rain is forecasted, that is when I do not ride  4) Not drinking enough fluids. Muscles really tighten up when you get dehydrated. 5) Trying to do a century on a mtn bike. Use a real road bike with road wheels/tires. The corollary of that is use a bike/equipment that you are familiar/comfortable with. A century is not the place for a maiden ride on a new bike.

Assos nut butter is the way to go . The pros put enough on that it works through the shorts and cause the saddle to shine. Assos costs more, but that is not an area to save money and then wish you had spent the extra bucks!

Sorry if this is more or different than you wanted to hear, but centuries can be a lot of fun. You do your first, and you start looking to do others.

FWIW, I have personally done some of the mistakes that I mentioned above.

Jim