Riding a bicycle 100 miles (a century) in a day is not an easy task. In order to successfully complete your ride and do so without inflicting too much pain on yourself you need to prepare well. One common error that catches people out is not planning what they will eat.
Riding a century places big demands on your body. You can expect to burn more calories riding a century that you would in up to 48 hours of normal active living. As a result it is essential that you fuel up sufficiently before, during and after your ride to ensure your success.
Start the day with a good hearty breakfast made up of mainly carbohydrates. Avoid fatty fried foods, instead opt for something like oatmeal with dried fruit in that is an excellent source of slow release energy. Be sure to drink plenty too to ensure dehydration does not get you.
You need to start replacing calories you will burn during the ride as soon as possible. The key here is little and often. Even if you are not hungry or thirsty, aim to eat and drink a little every 30 minutes of your ride. If you have difficulty remembering to do this set your wristwatch alarm to beep every 30 minutes to remind you. Once you fall into a calorie deficit it is virtually impossible to get out of it without stopping riding.
Eating the right foods after your century ride will increase your recovery time. Aim to drink some milk as soon as you get out of the saddle as it contains just the right balance of carbohydrates and protein. Follow it up with a good balanced meal within the next 2 hours. Again avoid fatty foods by having something like chicken with steamed rice and vegetables.