Eat

Eat and drink more than you usually do before, during, and after your ride. Having an insufficient store of calories and salt can cause cramping, lightheadedness, nausea, vomiting, depression, anxiety, and the like; see this site for a description of mental effects of bonking. These symptoms are caused by lack of fluid and electrolyte, but also because of a failure to intake sufficient calories. Bonking is no fun, and can make your wonderful day turn into a cruel slog, or worse: leave you hanging in the middle of nowhere, wondering how you're going to get home.

For a man of my stature and age, I burn about 636 calories an hour at a pace of about 15 mph. I rode for almost 6 hours yesterday, so burned about 3,816 calories. While it is not true that you can eat anything, if you don't replace your calories while riding, you will "bonk" or become cramped, irritable, and possibly unable to continue your ride.

Though this site is for runners, the principle applies to cyclists. To avoid bonking eat. Put your fad diet aside, and get your carbohydrates:

To ensure glycogen stores are high in both the liver, which the body accesses first, and the muscles, which are the bodies secondary source of glycogen during exercise, 75% of your diet should be composed of carbohydrates in the days leading up to a race or long run. Additionally, your pre-run meal should be comprised of approximately 80% carbohydrates. The main purpose of a pre-race meal is to provide the liver a full supply of glycogen, which is a reserve of energy that will be needed during an endurance run.

Cycling-specific advise is no different; eat:

When you eat is almost as important as what you eat. [Apart from your ordinary meals, a]bout an hour before a ride, fuel up with a high carbohydrate snack or small meal. Some ideas might be fresh fruit and whole grain toast or a half whole wheat bagel with peanut butter. 

[Plus you need to eat constantly on your long rides:] If your ride is longer than 60 minutes, you’ll need to refuel with more carbs. Researchers recommend about 30 to 40 grams of carbohydrate each 30 minutes you ride beyond the first 60 minutes. This might be a good time to consider a sports drink or energy bar. Eating a high carb snack or meal within 60 minutes after a lengthy ride is important to replenish your body and prepare you for your next ride.

Of course you don't want to eat crap either; plan ahead to have nutritious food available all along your ride. If you plan on going away from civilization, you need to pack it. Find nutrition-dense foods you can carry in your back pockets or pouch. Follow the link for some suggestions. I like a tortilla filled with banana, peanut butter, and honey. Plus I bring a couple Gu's, Cliff-bloks, an energy bar, and the like. And Gatorade or other electrolyte drinks contain carbs and calories; have one bottle filled with them. When your group stops, take stock of what you have, and if you need more, make them wait while you get what you need. It will take longer for them to wait while you recover from a bonk!

If you do bonk, you may have no choice but to get your bike and your body to some place safe and civilized. So, if you do rest, eat, and drink water. What to do?

What do you do if you bonk? You need to get your blood glucose levels up and you need to do it quickly. Ingest simple carbohydrates that can be rapidly processed into blood glucose by the digestive system. The best source for these kinds of carbs that you’re likely to have with you on the bike is a sports drink like Gatorade. Other sources of simple carbohydrates include energy gels (make sure you drink plenty of water with these), sugar cubes or sweet candy like gumdrops or jellybeans. Complex carbohydrates like energy bars will take longer to process into blood glucose and will only provide relief in the longer term. If you catch the bonk early, you can keep riding while you refuel. If you let the bonk go too far, get off the bike until you recover. You don’t want to be riding when your sense of balance is bad, you’re disoriented and you’re unaware of what’s going on around you.

So if you feel like you're bonking stop riding and eat and drink until you recover. Don't try to power through it.

What does all this mean? It means you must calculate your nutritional needs well in advance of your ride. You probably need to eat far more carbs than you are used to. You need to ensure that you have what you need on you when you go afield, and you need to stop and get what you need when you don't have it. But mostly it means: eat and drink. One of your water bottles must be filled with an electrolyte and one with water for long rides. Get them filled at all stops!

Summary:

1. Eat meals comprising 75% carbs in the days leading up to your ride.
2. Have a pre-ride meal of about 80% carbs.
3. Eat sufficient calories to replace those burned.
4. Eat 30-40 grams of carbs every 30 minutes during your ride.
5. Drink water and electrolytes during your ride.
6. If you bonk, rest and eat.
7. Know your body's nutritional needs and make sure you have access to nutritious food to replace lost calories and salt.

Riding is a supreme adventure, but it doesn't have to be a dangerous one.